bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bayesian Clustering and Product Partition Models
Authors: Quintana Fernando A. , Iglesias Pilar L. 
Published: December 2004

SummaryWe present a decision theoretic formulation of product partition models (PPMs) that allows a formal treatment of different decision problems such as estimation or hypothesis testing and clustering methods simultaneously. A key observation in our construction is the fact that PPMs can be formulated in the context of model selection. The underlying partition structure in these models is closely related to that arising in connection with Dirichlet processes. This allows a straightforward adaptation of some computational strategies—originally devised for nonparametric Bayesian problems—to our framework. The resulting algorithms are more flexible than other competing alternatives that are used for problems involving PPMs. We propose an algorithm that yields Bayes estimates of the quantities of interest and the groups of experimental units. We explore the application of our methods to the detection of outliers in normal and Student t regression models, with clustering structure equivalent to that induced by a Dirichlet process prior. We also discuss the sensitivity of the results considering different prior distributions for the partitions.
Gründungen an der Schnittstelle zwischen Wissenschaft und Wirtschaft – die Rolle der Hochschulen
Authors: Meyer-Krahmer Frieder , Kulicke Marianne 
Published: December 2004

Abstract In national innovation systems, universities are not only essential elements of the research infrastructure, but also main players in the field of education and further education. Their specific role in the interplay between knowledge production and market implementation of knowledge via start-ups derives from this fact. This article takes as its theme the university environment which supports and stimulates the start-up processes. It also shows the progress achieved in the German university landscape in recent years on the path towards a culture of entrepreneurship in teaching and research. This is manifested, for example, in the number of start-up chairs, the development of networks to exploit the start-up potential of universities together with regional partners, and in the numbers of spinoffs established.
Arbeitsmarktpolitik in der Europäischen Währungsunion
Authors: Berthold Norbert , Fehn Rainer 
Published: December 2004

Abstract While policymakers in Europe were busy implementing EMU during the past decade, persistently high unemployment, which should have been the main policy issue from a normative point of view, was essentially left untackled in most continental European countries. This poses the urgent question of which approach labor market policy should now take in fighting unemployment and which changes have come about with EMU. To deal with this question, the article proceeds in three steps. It is first shown that a web of institutions in labor, goods and capital markets, which are different from those Anglo-Saxon countries and which are interconnected by politico-economic forces, is to blame for the dismal situation on most continental European labor markets. Secondly, it is argued that EMU is not likely to boost employment growth automatically. Thirdly, it is outlined which are the key policy measures to alleviate unemployment in continental Europe and it is discussed whether EMU makes the actual implementation of these measures more likely.
Target‐to‐target interval versus probability effects on P300 in one‐ and two‐tone tasks
Authors: Croft R. J. , Gonsalvez C. J. , Gabriel C. , Barry R. J. 
Published: December 2004

AbstractThe P3(00) is an electrophysiological index of neural processing that varies with such stimulus parameters as interstimulus interval (ISI) and target probability, with a common view being that it reflects an endogenous form of memory update. Building on previous research, we argue that relations between P3 amplitude and both ISI and probability may be attributable to the target‐to‐target interval (TTI). Employing between‐subject (Experiment 1; N=24) and within‐subject (Experiment 2; N=10) designs, the present paper addresses this by testing subjects on a standard two‐tone auditory oddball task as well as a one‐tone task. In both studies, P3 amplitude increased and latency decreased linearly with TTI, and these relations were relatively unaffected by ISI or probability. This suggests that ISI and probability per se do not independently affect P3 amplitude, and that TTI offers a strong explanation of the reported relations between P3 amplitude and both ISI and probability.
Electrophysiological correlates of anticipatory and poststimulus components of task switching
Authors: Karayanidis Frini , Coltheart Max , Michie Patricia T. , Murphy Karen 
Published: December 2004

AbstractTask‐switching paradigms can shed light on cognitive and neural processes underlying attentional control mechanisms. An alternating runs task‐switching paradigm (R. D. Rogers & S. Monsell, 1995) is used to identify ERP components associated with anticipatory and poststimulus components of task‐switching processes. Subjects alternated between two tasks in a predictable series (AABB). Reaction time (RT) switch cost reduced with increasing response‐stimulus (R‐S) interval and a residual switch cost remained at the longest R‐S interval. A switch‐related positivity (D‐Pos) developed in the R‐S interval. D‐Pos was time‐locked to response onset, peaked around 400 ms post‐response onset, and was unaffected by task‐set interference. A switch‐related negativity (D‐Neg) emerged after stimulus onset. D‐Neg peaked earlier with increasing R‐S interval and its amplitude and latency were affected by task‐set interference. D‐Pos and D‐Neg were interpreted within current models of task‐switching.
An ERP study of change detection, change blindness, and visual awareness
Authors: Koivisto Mika , Revonsuo Antti 
Published: December 2004

AbstractElectrophysiological correlates of change detection and change blindness were studied in 12 observers. The ERP difference between detected changes and undetected changes was considered an electrophysiological correlate of visual awareness. Two distinct electrophysiological responses correlated with the awareness of change. First, awareness was associated with a negative amplitude shift at posterior sites around 200 ms after the change in the stimulus. The latency of the negative shift varied as a function of the task difficulty and the speed of becoming aware of the change. Second, ERPs to detected changes became more positive as compared with undetected changes around 400 ms after the change in the stimulus, peaking at parietal sites. We suggest that the earlier negativity is associated with a change in the content of visual awareness, whereas the later positivity may reflect more global processes needed in decision making and action planning.
MMN and attention: Competition for deviance detection
Authors: Sussman Elyse , Winkler István , Wang Wenjung 
Published: December 2004

AbstractWe addressed the question of whether the mismatch negativity (MMN) event‐related potential reflects an attention‐independent process. Previous studies have shown that the MMN response to intensity deviation was significantly reduced or even abolished when attention was highly focused on a concurrent sound channel, whereas no conclusive evidence of attentional sensitivity has been obtained for frequency deviation. We tested a new hypothesis suggesting that competition between detection of identical deviations in attended and unattended channels and the biasing of this competition induced by the subject's task account for the observed MMN effects. In a fast‐paced dichotic paradigm, we set up competition for frequency MMN and removed it for intensity MMN. We found that frequency MMN was now abolished in the unattended channel, whereas the amplitude of the intensity MMN was unaffected. These results support the competition hypothesis and suggest that selective attention in and of itself does not affect the MMN. Top‐down processes can determine what information reaches the deviance‐detection process when changes in multiple channels vie for the same MMN resource and one of the competing changes is relevant for the subject's task.
The music of speech: Music training facilitates pitch processing in both music and language
Authors: Schön Daniele , Magne Cyrille , Besson Mireille 
Published: December 2004

AbstractThe main aim of the present experiment was to determine whether extensive musical training facilitates pitch contour processing not only in music but also in language. We used a parametric manipulation of final notes' or words' fundamental frequency (F0), and we recorded behavioral and electrophysiological data to examine the precise time course of pitch processing. We compared professional musicians and nonmusicians. Results revealed that within both domains, musicians detected weak F0 manipulations better than nonmusicians. Moreover, F0 manipulations within both music and language elicited similar variations in brain electrical potentials, with overall shorter onset latency for musicians than for nonmusicians. Finally, the scalp distribution of an early negativity in the linguistic task varied with musical expertise, being largest over temporal sites bilaterally for musicians and largest centrally and over left temporal sites for nonmusicians. These results are taken as evidence that extensive musical training influences the perception of pitch contour in spoken language.
Best friends forever?: High school best friendships and the transition to college
Authors: Oswald Debra L. , Clark Eddie M. 
Published: December 2004

AbstractThe transition from high school to college is an important phase for adolescents in social as well as academic aspects. This study examined the changes that occur in high school best friendships during the first year of college. Results revealed that during the first year in college high school best friendships declined in satisfaction, commitment, rewards, and investments. During this period there was also an increase in costs and alternatives to best friend relationships. Proximity did not influence the friendships; however, level of communication did moderate friendship deterioration. Furthermore, individuals who continued their best friendship reported engaging in more maintenance behaviors of positivity, supportiveness, self‐disclosure, and interaction than individuals who reported a change in the relationship to close or casual friendship. Maintaining the best friendship also appeared to buffer adolescents from social loneliness. The results are discussed in terms of the implications of transitions on adolescent friendships.
Methodological issues in growth‐curve analyses with married couples
Authors: Kurdek Lawrence A. 
Published: December 2004

AbstractBecause longitudinal data are increasingly being used to test predictions regarding close relationships, researchers are also increasingly being confronted with methodological issues unique to the analysis of longitudinal data. In this paper, four issues in conducting growth‐curve analyses with married couples are examined: assessing statistical assumptions about homoscedastic and independent errors, handling information about missing data, dealing with couples with only one assessment, and estimating quadratic effects. Each issue is illustrated with actual data, and syntax from the multilevel module in LISREL 8.52 is provided for specific analyses. Guidelines are presented for helping researchers think through each issue with their own data set.
Within‐canopy variation in the rate of development of photosynthetic capacity is proportional to integrated quantum flux density in temperate deciduous trees
Authors: NIINEMETS Ü. , KULL O. , TENHUNEN J. D. 
Published: December 2004

ABSTRACTThe present study was undertaken to test for the hypothesis that the rate of development in the capacity for photosynthetic electron transport per unit area (Jmax;A), and maximum carboxylase activity of Rubisco (Vcmax;A) is proportional to average integrated daily quantum flux density (Qint) in a mixed deciduous forest dominated by the shade‐intolerant species Populus tremula L., and the shade‐tolerant species Tilia cordata Mill. We distinguished between the age‐dependent changes in net assimilation rates due to modifications in leaf dry mass per unit area (MA), foliar nitrogen content per unit dry mass (NM), and fractional partitioning of foliar nitrogen in the proteins of photosynthetic electron transport (FB), Rubisco (FR) and in light‐harvesting chlorophyll‐protein complexes (Vcmax;A ∝ MANMFR; Jmax;A ∝ MANMFB). In both species, increases in Jmax;A and Vcmax;A during leaf development were primarily determined by nitrogen allocation to growing leaves, increases in leaf nitrogen partitioning in photosynthetic machinery, and increases in MA. Canopy differences in the rate of development of leaf photosynthetic capacity were mainly controlled by the rate of change in MA. There was only small within‐canopy variation in the initial rate of biomass accumulation per unit Qint (slope of MA versus leaf age relationship per unit Qint), suggesting that canopy differences in the rate of development of Jmax;A and Vcmax;A are directly proportional to Qint. Nevertheless, MA, nitrogen, Jmax;A and Vcmax;A of mature leaves were not proportional to Qint because of a finite MA in leaves immediately after bud‐burst (light‐independent component of MA). MA, leaf chlorophyll contents and chlorophyll : N ratio of mature leaves were best correlated with the integrated average quantum flux density during leaf development, suggesting that foliar photosynthetic apparatus, once developed, is not affected by day‐to‐day fluctuations in Qint. However, for the upper canopy leaves of P. tremula and for the entire canopy of T. cordata, there was a continuous decline in N contents per unit dry mass in mature non‐senescent leaves on the order of 15–20% for a change of leaf age from 40 to 120 d, possibly manifesting nitrogen reallocation to bud formation. The decline in N contents led to similar decreases in leaf photosynthetic capacity and foliar chlorophyll contents. These data demonstrate that light‐dependent variation in the rate of developmental changes in MA determines canopy differences in photosynthetic capacity, whereas foliar photosynthetic apparatus is essentially constant in fully developed leaves.
Hydraulic limitations imposed by crown placement determine final size and shape of Quercus rubra L. leaves
Authors: ZWIENIECKI M. A. , BOYCE C. K. , HOLBROOK N. M. 
Published: December 2004

ABSTRACTThe canopies of large broad‐leaf trees exhibit significant heterogeneity in both micro‐environmental conditions and leaf morphology. Whether the visible differences in the size and shape of leaves from the top and bottom of the crown are determined prior to bud break or result from different patterns of leaf expansion is not known. Analysis of ontogenetic changes of both the degree of lobing and vein density in Quercus rubra demonstrates that leaves throughout the crown are identical in size and shape at the time of bud break. Morphological adaptation to the local micro‐environment takes place during the expansion phase and starts after the determination of the vascular architecture has been completed. Leaves from the bottom of the crown undergo greater expansion in the tissue close to the main veins than occurs either in the more peripheral tissue of the same leaf or anywhere in leaves from the top of the crown. This results in a water transport system that is well suited to the low evaporative rates near the bottom of the crown, but inadequate for the conditions found at the top of the tree. Acclimation of leaf form and function based upon differential expansion may be entirely driven by the local hydraulic demand during the expansion phase, resulting in leaf size and vein density being determined during development by the same hydraulic properties which will constrain the size of leaf that can be functionally supported at maturity.
Complementation of notabilis, an abscisic acid‐deficient mutant of tomato: importance of sequence context and utility of partial complementation
Authors: THOMPSON A. J. , THORNE E. T. , BURBIDGE A. , JACKSON A. C. , SHARP R. E. , TAYLOR I. B. 
Published: December 2004

AbstractThe abscisic acid (ABA)‐deficient tomato mutant notabilis (not) is believed to be a null mutation in the gene LeNCED1, encoding a 9‐cis‐epoxycarotenoid dioxygenase involved in ABA biosynthesis. We have sequenced and analysed a 19 kb genomic clone containing LeNCED1 and 5.4 kb of its promoter. This clone was transferred to not homozygotes and several non‐wilty transformed plants were obtained. The basal ABA content, water relations, shoot and root growth, adventitious rooting, ethylene evolution and ability to accumulate ABA under water stress are described for two of these lines, notcomp.13 and notcomp.1. Partial complementation was observed for most parameters measured for notcomp.1. Full complementation was observed in notcomp.13 for all parameters measured in whole plants under well‐watered and water‐stressed conditions. These data provide further evidence that LeNCED1 is the wild‐type allele of the not mutant gene. However, notcomp.13 was unable to accumulate the wild‐type levels of ABA in rapidly dehydrated leaves, indicating that it too was only partially complemented. Since LeNCED1 is an environmentally regulated gene encoding a rate‐limiting enzyme, precise levels and patterns of gene expression may be needed to fully recreate wild‐type phenotype. The utility of partially complemented lines to study the role of ABA in plant responses to stress conditions, and in promoter analysis, is discussed.
Role of an endogenous nitric oxide burst in the resistance of wheat to stripe rust
Authors: GUO P. , CAO Y. , LI Z. , ZHAO B. 
Published: December 2004

AbstractThe stripe rust (or yellow rust) disease caused by Puccinia striiformis Westend is a serious disease of wheat in many areas of the world. The role of NO, which is an important redox‐active signalling molecule in plants, was investigated in the wheat‐stripe rust system. The phenotypes from interactions of the same wheat variety, Lovrin10, with two different clones of stripe rust strains (P. striiformis Westend), namely China yellow rust (CY)22‐2 and CY29‐1, which are immune and susceptible reaction types, respectively. The time course of host endogenous NO detected by electron spin resonance indicated that recognition of an avirulent strain was associated with two peaks of NO production. The first peak of NO accumulated in the early infection stage whereas the second peak accumulated in the latent period; however, only a single peak of NO was observed in the latent period for the virulent strain. Furthermore, the activity of pathogen‐related protein‐phenylalanine ammonia‐lyase was higher in the resistant system than in the susceptible system, which suggested that the first NO production was associated with resistance. Exogenous NO improved the activity of phenylalanine ammonia‐lyase and induced a resistant response of Lovrin10 to the virulent strain CY29‐1, thereby providing further evidence that the first peak of NO production was associated with resistance. These results indicate that the first NO burst in the immune system plays an important role in the resistant reaction of wheat to strip rust.
Pseudomonas syringae pv. maculicola in Australia: pathogenic, phenotypic and genetic diversity
Authors: Peters B. J. , Ash G. J. , Cother E. J. , Hailstones D. L. , Noble D. H. , Urwin N. A. R. 
Published: December 2004

Pseudomonas syringae pv. maculicola causes bacterial leaf spot on cruciferous plants in Australia. This is the first record confirming the identity of seven isolates currently stored as P. syringae pv. maculicola in the herbarium of the Department of Agriculture, Orange, Australia (Herb. DAR). The isolates were identified using pathogenicity testing on cauliflower and fatty acid methyl ester analysis. They clustered together using repetitive sequence‐based polymerase chain reaction (rep‐PCR) and PCR‐restriction fragment‐length polymorphism (RFLP) of the 16S−23S internal transcribed spacer region (ITS) using seven restriction enzymes. Identification was confirmed by comparison of these isolates with known overseas isolates of P. syringae pv. maculicola, but there was significant variation in their pathogenicity and genetic structure.
Interval Estimation for Log-Linear Models with One Variable Subject to Non-Ignorable Non-Response
Authors: Clarke Paul S. , Smith Peter W. F. 
Published: December 2004

SummaryLog-linear models for multiway contingency tables where one variable is subject to non-ignorable non-response will often yield boundary solutions, with the probability of non-respondents being classified in some cells of the table estimated as 0. The paper considers the effect of this non-standard behaviour on two methods of interval estimation based on the distribution of the maximum likelihood estimator. The first method relies on the estimator being approximately normally distributed with variance equal to the inverse of the information matrix. It is shown that the information matrix is singular for boundary solutions, but intervals can be calculated after a simple transformation. For the second method, based on the bootstrap, asymptotic results suggest that the coverage properties may be poor for boundary solutions. Both methods are compared with profile likelihood intervals in a simulation study based on data from the British General Election Panel Study. The results of this study indicate that all three methods perform poorly for a parameter of the non-response model, whereas they all perform well for a parameter of the margin model, irrespective of whether or not there is a boundary solution.
Estimating Functions in Indirect Inference
Authors: Heggland Knut , Frigessi Arnoldo 
Published: December 2004

SummaryThere are models for which the evaluation of the likelihood is infeasible in practice. For these models the Metropolis–Hastings acceptance probability cannot be easily computed. This is the case, for instance, when only departure times from a G/G/1 queue are observed and inference on the arrival and service distributions are required. Indirect inference is a method to estimate a parameter θ in models whose likelihood function does not have an analytical closed form, but from which random samples can be drawn for fixed values of θ. First an auxiliary model is chosen whose parameter β can be directly estimated. Next, the parameters in the auxiliary model are estimated for the original data, leading to an estimate β^. The parameter β is also estimated by using several sampled data sets, simulated from the original model for different values of the original parameter θ. Finally, the parameter θ which leads to the best match to β^ is chosen as the indirect inference estimate. We analyse which properties an auxiliary model should have to give satisfactory indirect inference. We look at the situation where the data are summarized in a vector statistic T, and the auxiliary model is chosen so that inference on β is drawn from T only. Under appropriate assumptions the asymptotic covariance matrix of the indirect estimators is proportional to the asymptotic covariance matrix of T and componentwise inversely proportional to the square of the derivative, with respect to θ, of the expected value of T. We discuss how these results can be used in selecting good estimating functions. We apply our findings to the queuing problem.