bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrogen superpermeation resistant to ion sputtering
Authors: Livshits A. I. , Alimov V. N. , Notkin M. E. , Bacal M.
Published: September 2002

A nonmetallic monolayer on the surface of a metallic membrane gives rise to the superpermeation of suprathermal hydrogen. This means that virtually the whole implanted flux passes through the membrane, not depending on membrane temperature and thickness. The fact that superpermeation is degrading at a sufficiently high energy of incident hydrogen particles was considered a “natural” result of sputtering of the monolayer. It is now proven that Nb containing an O impurity would be normally superpermeable to suprathermal hydrogen at any incident energy, whereas the “usual” sensitivity to sputtering is conditioned by a NbC layer originally present at the “real” surface of Nb.
1 mW AlInGaN-based ultraviolet light-emitting diode with an emission wavelength of 348 nm grown on sapphire substrate
Authors: Wang T. , Liu Y. H. , Lee Y. B. , Ao J. P. , Bai J. , Sakai S.
Published: September 2002

By introducing the AlInGaN/AlGaN quaternary system as an active region, we fabricated an UV light-emitting diode (LED) with an emission wavelength of 348 nm. The optical power is 1 mW at an injection current of 50 mA under a bare-chip geometry, which is the highest report among UV–LEDs with an emission wavelength of around 350 nm grown on sapphire substrate. It means that the optical power of such LEDs is high enough to be used in practical application. In contrast to it, a similar UV–LED based on GaN/AlGaN system as an active region has been also grown, whose optical power is less than that of the AlInGaN/AlGaN-based UV–LED by one order of magnitude. The temperature-dependent photoluminescence study indicates that there exists a strong exciton-localization effect in the AlInGaN/AlGaN material system, while there is no distinguished exciton-localization effect in the GaN/AlGaN material system. Therefore, the high performance of the AlInGaN/AlGaN-based UV–LED can be attributed to the enhanced exciton-localization effect.
Effect of H2O adsorption on electron transport in a carbon nanotube
Authors: Pati Ranjit , Zhang Yiming , Nayak Saroj K. , Ajayan Pulickel M.
Published: September 2002

We have studied the adsorption of H2O molecules on a single-wall carbon nanotube (NT) using first-principles gradient-corrected density-functional theory. Subsequently, Green’s function-based Landauer–Büttiker multichannel formalism within a tight-binding model is used to calculate the electron transport, and our results suggest that H2O molecules adsorbed on the NT surface reduce the electronic conduction in the tube in agreement with recent experimental measurements. The decrease of conductance with water adsorption is explained on the basis of charge transfer between the adsorbate and the NT.
Charge trapping in light-emitting SiO2 layers implanted with Ge+ ions
Authors: Gebel T. , Rebohle L. , Skorupa W. , Nazarov A. N. , Osiyuk I. N. , Lysenko V. S.
Published: September 2002

The trapping effects of negative and positive charge in Ge-enriched SiO2 layers during high-field electron injection from the Si substrate of Al–SiO2–Si structures are studied. The capture cross section and the concentration of negatively and positively charged traps are estimated and the location of the positively charged traps is determined. It is shown that increasing rapid thermal annealing time from 6 to 150 s at 1000 °C leads to an enhanced diffusion of Ge towards the SiO2–Si interface and an increase in negatively and positively charged trap concentration. The mechanisms of the trap generation are discussed.
Analysis of grain-boundary effects on the electrical properties of Pb(Zr,Ti)O3 thin films
Authors: Lee Jang-Sik , Joo Seung-Ki
Published: September 2002

The effects of grain boundaries on the characteristics of Pb(Zr,Ti)O3 (PZT) thin films were investigated by locating the top electrode within grain, on the line boundary, or on the grain-boundary intersection in a controlled manner. It turned out that, when there was no grain boundary in the area measured, excellent ferroelectric and electrical performance was obtained. On the other hand, serious degradation was observed in terms of polarization, leakage current, breakdown field, and fatigue characteristics when grain boundaries were included in the area studied. It was found that degradation of PZT thin films was closely correlated with the length of grain boundary in the area measured.
Generation of palladium clusters on Au(111) electrodes: Experiments and simulations
Authors: Del Popolo M. , Leiva E. , Kleine H. , Meier J. , Stimming U. , Mariscal M. , Schmickler W.
Published: September 2002

The properties of palladium clusters, generated with the electrochemical scanning tunneling microscope, have been investigated both by experiments and by computer simulations. The clusters are found to be larger and more stable if the tip is moved further towards the electrode surface in the generation process. The simulations suggest that the larger clusters consist of a palladium–gold mixture, which is more stable than pure palladium. Dissolution of the clusters occurs from the edges rather than layer by layer.
Operation of nanomechanical resonant structures in air
Authors: Sekaric L. , Zalalutdinov M. , Bhiladvala R. B. , Zehnder A. T. , Parpia J. M. , Craighead H. G.
Published: September 2002

We report on the resonant operation of high-quality-factor silicon nanomechanical structures in air and at room temperature. We describe techniques used to actuate and detect nanomechanical structures in atmosphere, resulting in the enhancement of the effective quality factor to above 1000 and demonstrate the potential for successful sensor operation of resonant nanomechanical structures under ambient conditions.
Submicron extreme ultraviolet imaging using high-harmonic radiation
Authors: Wieland Marek , Frueke Rolf , Wilhein Thomas , Spielmann Christian , Pohl Martin , Kleineberg Ulf
Published: September 2002

We report on experiments using high-harmonic (HH) radiation for microscopy imaging at 13 nm wavelength. A simple setup using a zone plate as objective and a back-illuminated CCD as detector yields at moderate magnifications of M≈60 a spatial resolution of δx<0.8 μm demonstrated with a sample of mica. The HH radiation was monochromatized by means of a high-efficiency multilayer monochromator consisting of two Mo/Si-mirros.
Low-threshold-current-density 1300-nm dilute-nitride quantum well lasers
Authors: Tansu Nelson , Kirsch Nicholas J. , Mawst Luke J.
Published: September 2002

Metalorganic chemical vapor deposition-grown In0.4Ga0.6As0.995N0.005 quantum well (QW) lasers have been realized, at an emission wavelength of 1.295 μm, with threshold and transparency current densities as low as 211 A/cm2 (for L=2000 μm) and 75 A/cm2, respectively. The utilization of a tensile-strained GaAs0.67P0.33 buffer layer and GaAs0.85P0.15 barrier layers allows a highly-compressively-strained In0.4Ga0.6As0.995N0.005 QW to be grown on a high-Al-content lower cladding layer, resulting in devices with high current injection efficiency (ηinj∼97%).
Micro-Raman studies of vertical-cavity surface-emitting lasers with AlxOy/GaAs distributed Bragg reflectors
Authors: Haisler V. A. , Hopfer F. , Sellin R. L. , Lochmann A. , Fleischer K. , Esser N. , Richter W. , Ledentsov N. N. , Bimberg D. , Möller C. , Grote N.
Published: September 2002

Micro-Raman spectroscopy studies of the oxidation processes in high Al content AlxGa1−xAs layers used in distributed Bragg reflectors (DBRs) in vertical-cavity surface-emitting lasers (VCSELs) are presented. Precise characterization of the composition of oxidized layers, control over residual As precipitates, as well as the determination of the mechanical strain in DBR layers is demonstrated. Proper optimization of the processing steps on the basis of Micro-Raman spectroscopy allows the realization of reliable oxide-DBR VCSELs.
Magnetic properties of (Al,Ga,Mn)As
Authors: Takamura K. , Matsukura F. , Chiba D. , Ohno H.
Published: September 2002

Epitaxial (Al,Ga,Mn)As films were prepared by low-temperature molecular-beam epitaxy and their magnetic properties were investigated. The Mn composition was fixed at approximately 0.05 while Al composition was varied up to 0.30. The results of magnetization and transport measurements for high Al composition samples show an out-of-plane magnetic easy axis and insulating behavior. This is quite different from those of (Ga,Mn)As films grown under the same growth conditions. The postgrowth annealing modified both the anisotropy and conductivity, indicating the presence of correlation between them. Preparation and characterization of the (Al,Ga,Mn)As-based heterostructures are also presented.
Coercive and switching fields in ferroelectric ceramics
Authors: Arlt G. , Calderwood J. H.
Published: September 2002

The coercive field in ferroelectric ceramics is, in general, significantly smaller than the switching field, i.e., the field necessary to reverse the direction of polarization within an individual grain of the material. It is shown that a factor contributing to this difference is that the grain gives rise to an internal field which assists the applied field in the bringing about the switching in other grains.
Analysis of low-frequency noise in boron-doped polycrystalline silicon–germanium resistors
Authors: Chen Kun-Ming , Huang Guo-Wei , Chiu D. Y. , Huang Hsiang-Jen , Chang Chun-Yen
Published: September 2002

Low-frequency noise in boron-doped polycrystalline silicon–germanium (poly-Si1−xGex) resistors at various temperatures is studied. The poly-Si1−xGex films with 0%∼36% Ge content were grown using ultrahigh vacuum chemical molecular epitaxy system. We find that the low-frequency noise in poly-Si1−xGex decreases with increasing Ge content, due to the lower potential barrier height of grain boundaries in higher Ge content samples. Moreover, the low-frequency noise decreases with increasing temperature. These results are well explained by the carrier mobility fluctuation model.
Three-dimensional band mapping of graphite
Authors: Matsui Fumihiko , Hori Yoshiaki , Miyata Hiroaki , Suganuma Nobutaka , Daimon Hiroshi , Totsuka Hidekazu , Ogawa Koji , Furukubo Tomoya , Namba Hidetoshi
Published: September 2002

We developed a method to visualize the curved surfaces of valence band dispersion by a display-type spherical mirror analyzer. The π and σ band “surfaces” of graphite measured and displayed three dimensionally contain fruitful information compared to the conventional band dispersion “curves” along a certain direction in k space. The slope and the curvature of local band structure correspond to the velocity and the mass of the valence electrons. By integrating band energy over the entire Brillouin zone, the electronic part of the condensation energy is obtained. Furthermore, the atomic orbitals composing each band are determined from two-dimensional photoelectron intensity distribution by using linearly polarized synchrotron radiation.
Raman characterization of boron-doped multiwalled carbon nanotubes
Authors: Maultzsch J. , Reich S. , Thomsen C. , Webster S. , Czerw R. , Carroll D. L. , Vieira S. M. C. , Birkett P. R. , Rego C. A.
Published: September 2002

We present first- and second-order Raman spectra of boron-doped multiwalled carbon nanotubes. The Raman intensities are analyzed as a function of the nominal boron concentration. The intensities of both the D mode and the high-energy mode in the first-order spectra increase with increasing boron concentration, if normalized with respect to a second-order mode. We interpret this result as an indication that the high-energy mode in carbon nanotubes is defect-induced in a similar way as the D mode. Based on this result, we provide a preliminary quantitative relation between the boron concentration and the Raman intensity ratios.
Böhmische Skizzen: Reflections on Social Space and Nationhood in Nineteenth-Century Prague
Authors: Šimůnková Alena
Published: September 2002

Shortly before the Christmas of 1860, the major bookstores in Prague put on display a German-language booklet entitledBohemian Sketches: By a Native Writer.Although the book was published anonymously, its author soon became well known: he was Jan Palacký, the son of the prominent historian and leading Czech politician Frantis̆ek Palacký. But even his famous name did not spare the young man from stormy, harsh criticism that followed after the publication of the book. For weeks the newspapers both in Prague and in Vienna scrutinized the rhetorical nuances of the book, pointing out the author's national and political biases. Surprisingly, neither of the Czech-language newspapers,Národní listynorC̆as, that had recently entered into the public arena, stepped forward in defense of the author. The critical response in the press raises one's curiosity: what was wrong with Jan Palacký's arguments? How could someone so closely connected with Czech national leaders write such a controversial account? Moreover, considering the censorship practices and vigilant police supervision of the time, it is also worth asking how the publication could have escaped the attention of governmental surveillance.
Print Capitalism or Patronage, Propaganda, and Policing: The Emergence of Printing and the Periodical Press in Bohemia
Authors: Leigh Jeffrey T.
Published: September 2002

Over the last twenty years, the theoretical perspectives of Benedict Anderson and Ernest Gellner have played a large role in discussions of the origins and development of nationalism. In each of their conceptions is not only the now famous and widely agreed upon notion that “nationalism engenders nations,” and that nations “imagine” themselves into existence, but also that such development is inherently connected with underlying economic developments associated with the rise of capitalism and industrialization. For each of these theorists, communication plays a central role, a defining function, in the rise of nationalism.
Aristocrats, Gypsies, and Cowboys All: Film Stereotypes and Hungarian National Identity in the 1930s
Authors: Frey David S.
Published: September 2002

Among social psychologists, there has long been a debate over the concept of the stereotype. Are stereotypes meant mainly for consumption by an in-group or are they designed by and for curious outsiders? Are they primarily individual or collective? Are they benign generalizations and categories that make it easier for individuals or groups to perceive and organize the world around them? Or are they insipid and unsustainable generalizations, based on false information, exaggeration, unfairly rigid conceptual categories, or even the observer's laziness? Do they beget understanding or prejudice? These questions, many of which were first raised by Walter Lippmann when he published Public Opinion in 1922, still polarize the psychological profession today. They also continue to confound politicians who wish to construct coherent, distinct, and vibrant identities for their nations.
From Silence to Justification?: Moldovan Historians on the Holocaust of Bessarabian and Transnistrian Jews
Authors: Solonari Vladimir
Published: September 2002

The Holocaust was one of the major experiences of the populations, both Jewish and non-Jewish, of those European countries that were either part of the Axis or occupied by Nazi Germany. This was certainly the case for the inhabitants of Bessarabia, Northern Bukovina, and Transnistria. These regions remained under Romanian administration from June/July 1941 to spring/summer 1944. The Soviets had seized Bessarabia and Northern Bukovina from Romania in June 1940 under the Molotov–Ribbentrop Pact. These territories were then reoccupied (“liberated”) by the Romanian and German armies after the German attack against the Soviet Union in June 1941. From 1941 to 1944 they were Romanian provinces ruled by separate highly centralized administrations. Transnistria (meaning literally “territory across the Dniester” in Romanian), which lies between the Dniester and Bug rivers, though never formally incorporated into Romania, was ruled by the Romanians during this period under the agreement with Hitler. Romanian authorities deported practically all Jews from Bessarabia and Northern Bukovina to Transnistria, accusing them of both treason and collaboration with the Soviets in 1940–1941 during the Soviet occupation and hostility towards the Romanian state in general. Some Roma, together with other “hostile elements” from other Romanian provinces, were also deported to Transnistria.
Memories of Nations and States: Institutional History and National Identity in Post-Soviet Eurasia
Authors: Abdelal Rawi
Published: September 2002

The national identities of post-Soviet societies profoundly influenced the politics and economics of Eurasia during the 1990s. These identities varied along two distinct but related dimensions: their content and contestation. Nationalist movements throughout post-Soviet Eurasia invoked their nations in support of specific purposes, which frequently cast Russia as the nation's most important “other” and the state from which autonomy and security must be sought. Nationalists therefore offered specific proposals for the content of their societies’ collective identities. But not everyone in these societies shared the priorities of their nationalist movements. Indeed, the international relations among post-Soviet states often revolved around one central question: did post-Soviet societies and politicians agree with their nationalists or not? The former Communists played a decisive role in contesting the content of national identity. One of the defining differences among post-Soviet states during the 1990s was the political and ideological relationship in each one between the formerly Communist elites and the nationalists—whether the former Communists marginalized the nationalists, arrested them, coopted them, bargained with them, or even tried to become like them. These different relationships revealed different degrees and kinds of societal consensus about national identity after Soviet rule.
A quantitative model of optimal data selection in Wason's selection task
Authors: Hattori Masasi
Published: September 2002

The optimal data selection model proposed by Oaksford and Chater (1994) successfully formalized Wason's selection task (Wason, 1966). The model, however, involved some questionable assumptions and was also not sufficient as a model of the task because it could not provide quantitative predictions of the card selection frequencies. In this paper, the model was revised to provide quantitative fits to the data. The model can predict the selection frequencies of cards based on a selection tendency function (STF), or conversely, it enables the estimation of subjective probabilities from data. Past experimental data were first re-analysed based on the model. In Experiment 1, the superiority of the revised model was shown. However, when the relationship between antecedent and consequent was forced to deviate from the biconditional form, the model was not supported. In Experiment 2, it was shown that sufficient emphasis on probabilistic information can affect participants’ performance. A detailed experimental method to sort participants by probabilistic strategies was introduced. Here, the model was supported by a subgroup of participants who used the probabilistic strategy. Finally, the results were discussed from the viewpoint of adaptive rationality.
Evidence against hyperspecificity in implicit invariant learning
Authors: Newell Ben R. , Bright James E. H.
Published: September 2002

Four experiments examined the claim that cross-format transfer in invariant learning is reliant solely on the presence of repetition structure in study and test strings (Stadler, Warren, Lesch, 2000). Experiments 1, 2, and 3 used strings with no repetitions and found significant cross-format transfer in combination with a non-significant transfer decrement - no significant difference between same- and changed-format conditions. Further investigation of the basis of the role of repetition structure revealed an emphasis on the perceptual salience of test stimuli (Experiment 4). Our results contrast with those of Stadler et al. and suggest that under the conditions we employed invariant learning is not highly sensitive to changes in the perceptual characteristics of stimuli and therefore is inaccurately described as hyper specific. We suggest that the term hyper specific be reserved for cases in which minor format changes result in significant performance impairments - for example, typographical effects in implicit memory.
Parafoveal-on-foveal interactions in word recognition
Authors: Kennedy Alan , Pynte Joël , Ducrot Stéphanie
Published: September 2002

An experiment is reported in which participants read sequences of five words, looking for items describing articles of clothing. The third and fourth words in critical sequences were defined as “foveal” and “parafoveal” words, respectively. The length and frequency of foveal words and the length, frequency, and initial-letter constraint of parafoveal words were manipulated. Gaze and refixation rate on the foveal word were measured as a function of properties of the parafoveal word. The results show that measured gaze on a given foveal word is systematically modulated by properties of an unfixated parafoveal word. It is suggested that apparent inconsistencies in previous studies of parafoveal-on-foveal effects relate to a failure to control for foveal word length and hence the visibility of parafoveal words. A serial-sequential attention-switching model of eye movement control cannot account for the pattern of obtained effects. The data are also incompatible with various forms of parallel-processing model. They are best accounted for by postulating a process-monitoring mechanism, sensitive to the simultaneous rate of acquisition of information from foveal and parafoveal sources.
Consciousness is slower than you think
Authors: Rabbitt Patrick
Published: September 2002

In easy serial choice reaction time tasks (CRT tasks) young adults can very rapidly “correct” nearly all their errors by making the responses that they should have made (error-correcting responses). They are much less accurate at signalling their errors by making the same, deliberate, response to each (error-signalling responses), and they poorly remember errors that they have not signalled or corrected. When instructed to ignore errors they nevertheless involuntarily register them because the response immediately following them (responses following unacknowledged errors) are unusually slow, and they sometimes make involuntary error correction responses. Errors that are neither signalled nor remembered are registered at some level because responses following unacknowledged errors are slowed. Old age does not impair the accuracy of error correction or reduce the proportion of errors that are acknowledged because they are followed by unusually slow responses, but it does reduce the accuracy of error signalling and of recall of errors. Groups of 40 young adults (mean age 20.1 years, SD 1.1) and 40 older adults (mean 71.2 years, SD 5.1) signalled and recalled their errors increasingly accurately as intervals between each response and the next signal were increased from 150 ms to 1000 ms. Error signalling and recall improved as response-signal interval (RSI) durations increased, reaching asymptote at RSIs of 800 ms for the young and 1000 ms for the older adults. Thus processes necessary for conscious and deliberate choice or error-signalling responses and for subsequent recall of errors require more than 150 ms to complete, are slowed by old age, and may be interrupted by onset of new signals occurring earlier than 800 to 1000 ms after completion of an incorrect response.
358,534 nonwords: The ARC Nonword Database
Authors: Rastle Kathleen , Harrington Jonathan , Coltheart Max
Published: September 2002

The authors present a model of the phonotactic and orthographic constraints of Australian and Standard Southern British English monosyllables. This model is used as the basis for a web-based psycholinguistic resource, the ARC Nonword Database, which contains 358,534 monosyllabic nonwords—48,534 pseudohomophones and 310,000 non-pseudohomophonic nonwords. Items can be selected from the ARC Nonword Database on the basis of a wide variety of properties known or suspected to be of theoretical importance for the investigation of reading.
Syllogistic reasoning and cognitive ageing
Authors: Fisk John E. , Sharp Charles
Published: September 2002

Gilinsky and Judd (1994) demonstrated that age-related impairment in syllogistic reasoning was in part due to reduced working-memory capacity. A total of 30 older (average age 66 years) and 34 younger persons (average age 24 years) were tested on syllogisms of various types as well as on other measures. Syllogistic reasoning was significantly correlated with education, processing speed, word span, and word fluency. Correlations with visuo-spatial processing and random letter generation were just short of significance. Syllogistic reasoning performance declined with age, although the deficit was no longer statistically significant following control for age-related differences in information-processing speed. On the other hand the inclusion of word fluency as an additional covariate boosted the apparent age effect, returning it to statistical significance. Thus it is possible that cognitive processes outside of working memory might underpin at least part of the apparent age deficit. This possibility is evaluated in the light of neuropsychological evidence implicating the prefrontal cortex in both the processing of syllogisms and more generally in cognitive ageing.
Semantic priming in number naming
Authors: Reynvoet Bert , Brysbaert Marc , Fias Wim
Published: September 2002

The issue of semantic and non-semantic conversion routes for numerals is still debated in numerical cognition. We report two number-naming experiments in which the target numerals were preceded by another numeral (prime). The primes and targets could be presented either in arabic (digit) notation or in verbal (alphabetical) notation. The results reveal a semantically related distance effect: Latencies are fastest when the prime has the same value as the target and increase when the distance between prime and target increases. We argue that the present results are congruent with the idea that the numerals make access to an ordered semantic number line common to all notations, as the results are the same for within-notation priming (arabic-arabic or verbal- verbal) and between-notations priming (arabic-verbal or verbal-arabic). The present results also point to a rapid involvement of semantics in the naming of numerals, also when the numerals are words. As such, they are in line with recent claims of rapid semantic mediation in word naming.
Temporal and causal order effects in thinking about what might have been
Authors: Segura Susana , Fernandez-Berrocal Pablo , Byrne Ruth M. J.
Published: September 2002

When people think counterfactually about what might have been different for a sequence of events, they are influenced by the order in which the events occurred. They tend to mentally undo the most recent event in a temporal sequence of two events. But they tend to mentally undo the first event in a causal sequence of four events. We report the results of two experiments that show that the temporal and causal order effects are not dependent on the number of events in the sequence. Our first experiment, with 300 participants, shows that the temporal order effect occurs for sequences with four events as well as for sequences with two events. Our second experiment, with 372 participants, shows that the causal order effect occurs for sequences with two events as well as for sequences with four events. We discuss the results in terms of the mental representations that people construct of temporal and causal sequences.
Associative priming in a masked perceptual identification task: Evidence for automatic processes
Authors: Pecher Diane , Zeelenberg René , Raaijmakers Jeroen G. W.
Published: September 2002

Two experiments investigated the influence of automatic and strategic processes on associative priming effects in a perceptual identification task in which prime-target pairs are briefly presented and masked. In this paradigm, priming is defined as a higher percentage of correctly identified targets for related pairs than for unrelated pairs. In Experiment 1, priming was obtained for mediated word pairs. This mediated priming effect was affected neither by the presence of direct associations nor by the presentation time of the primes, indicating that automatic priming effects play a role in perceptual identification. Experiment 2 showed that the priming effect was not affected by the proportion (.90 vs..10) of related pairs if primes were presented briefly to prevent their identification. However, a large proportion effect was found when primes were presented for 1000 ms so that they were clearly visible. These results indicate that priming in a masked perceptual identification task is the result of automatic processes and is not affected by strategies. The present paradigm provides a valuable alternative to more commonly used tasks such as lexical decision.
Stimulus-response compatibility in intensity-force relations
Authors: Mattes Stefan , Leuthold Hartmut , Ulrich Rolf
Published: September 2002

Romaiguère, Hasbroucq, Possamaï, and Seal (1993) reported a new compatibility effect from a task that required responses of two different target force levels to stimuli of two different intensities. Reaction times were shorter when high and low stimulus intensities were mapped to strong and weak force presses respectively than when this mapping was reversed. We conducted six experiments to refine the interpretation of this effect. Experiments 1 to 4 demonstrated that the compatibility effect is clearly larger for auditory than for visual stimuli. Experiments 5 and 6 generalized this finding to a task where stimulus intensity was irrelevant. This modality difference refines Romaiguère et al.'s (1993) symbolic coding interpretation by showing that modality-specific codes underlie the intensity-force compatibility effect. Possible accounts in terms of differences in the representational mode and action effects are discussed.
Scalar timing in temporal generalization in children with short and long stimulus durations
Authors: Droit-Volet Sylvie
Published: September 2002

This experiment investigated temporal generalization performance in children aged 3, 5, and 8 years by using auditory stimulus durations where the standard was 0.4 s or 4.0 s, and non-standard stimuli were spaced linearly around the standard. At all ages, generalization gradients superimposed well when plotted on the same relative scale, indicating conformity to scalar timing. Whatever the standard duration used, the principal developmental changes were the increasing steepness of the generalization gradient with increasing age and a shift from symmetrical gradients, in the 3- and 5-year-olds, to adult-like asymmetrical gradients in the 8-year-olds.
Expertise, attention, and memory in sensorimotor skill execution: Impact of novel task constraints on dual-task performance and episodic memory
Authors: Beilock Sian L. , Wierenga Sarah A. , Carr Thomas H.
Published: September 2002

Two experiments explored the attention and memory processes governing sensorimotor skill. Experiment 1 compared novice and experienced golf putting performance in single-task (putting in isolation) and dual-task conditions (putting while performing an auditory word search task). At specific intervals, participants also produced episodic descriptions of specific putts. Experiment 2 assessed novice performance following training on the same putting task. In Experiment 1, experienced golfers did not differ in putting accuracy from single- to dual-task conditions and, compared to novices, had higher recognition memory for words heard while putting but diminished episodic memories of specific putts. However, when using an s-shaped arbitrarily weighted “funny putter” designed to disrupt the mechanics of skill execution, experienced golfers produced extensive episodic memories of specific putts but showed decreased dual-task putting accuracy and recognition memory for secondary task words. Trained novices produced results intermediate between the untrained novices and experienced golfers. As predicted by current theories of practice-based automaticity, expertise leads to proceduralized control that does not require constant attention. Resources are free to devote to secondary task demands, yet episodic memory for primary task performance is impoverished. Novel task constraints (e.g., a funny putter) increase attention to execution, compromising secondary task performance but enhancing memory for skill execution.
The locus of semantic priming effects in person recognition
Authors: McNeill Allan , Burton A. Mike
Published: September 2002

Semantic priming in person recognition has been studied extensively. In a typical experiment, participants are asked to make a familiarity decision to target items that have been immediately preceded by related or unrelated primes. Facilitation is usually observed from related primes, and this priming is equivalent across stimulus domains (i.e., faces and names prime one another equally). Structural models of face recognition (e.g., IAC: Burton, Bruce, Johnston, 1990) accommodate these effects by proposing a level of person identity nodes (PINs) at which recognition routes converge, and which allow access to a common pool of semantics. We present three experiments that examine semantic priming for different decisions. Priming for a semantic decision (e.g., British/American?) shows exactly the same pattern that is normally observed for a familiarity decision. The pattern is equivalent for name and face recognition. However, no semantic priming is observed when participants are asked to make a sex decision. These results constrain future models of face processing and are discussed with reference to current theories of semantic priming.
Language familiarity effects in short-term memory: The role of output delay and long-term knowledge
Authors: Thorn Annabel S. C. , Gathercole Susan E. , Frankish Clive R.
Published: September 2002

Four experiments examined the origins of language familiarity effects in bilingual short-term recall. In Experiments 1A and 1B, bilingual adults were tested on serial recall and probed serial recall of words and nonwords in their first and second languages. A first-language advantage was obtained on both measures, indicating that the beneficial effects of language familiarity are not exclusively attributable to lesser output delay during overt recall. In Experiments 2A and 2B, the same group of bilinguals was tested on serial recall and serial recognition of word lists in both languages. Although a sizeable first-language advantage was obtained on the serial recall measure, recognition performance was comparable in the two languages. On the basis of these results it is suggested that language differences in bilingual immediate memory arise in large part as a consequence of the differential availability of language-specific long-term knowledge with which to support retrieval processes in serial recall.
The hippocampus, space, and viewpoints in episodic memory
Authors: Burgess Neil
Published: September 2002

A computational model of how single neurons in and around the rat hippocampus support spatial navigation is reviewed. The extension of this model, to include the retrieval from human long-term memory of spatial scenes and the spatial context of events is discussed. The model explores the link between spatial and mnemonic functions by supposing that retrieval of spatial information from long-term storage requires the imposition of a particular viewpoint. It is consistent with data relating to representational hemispatial neglect and the involvement of the mammillary bodies, anterior thalamus, and hippocampal formation in supporting both episodic recall and the representation of head direction. Some recent behavioural, neuropsychological, and functional neuroimaging experiments are reviewed, in which virtual reality is used to allow controlled study of navigation and memory for events set within a rich large-scale spatial context. These studies provide convergent evidence that the human hippocampus is involved in both tasks, with some lateralization of function (navigation on the right and episodic memory on the left). A further experiment indicates hippocampal involvement in retrieval of spatial information from a shifted viewpoint. I speculate that the hippocampal role in episodic recollection relates to its ability to represent a viewpoint moving within a spatial framework.
Generate and test: An alternative route to knowledge elicitation in an implicit learning task
Authors: Huddy Vyv , Burton A. Mike
Published: September 2002

Three experiments are reported, which examine generation of knowledge in the McGeorge and Burton (1990) invariant learning task. In this task, participants are exposed to 30 four-digit numbers containing an invariant “3”. Following this participants then demonstrate a preference for novel numbers containing this invariant over numbers without it. Despite above-chance performance on this pseudo-memory test, participants appear unable to verbalize anything pertinent to the invariant. Here we introduce a novel version of this task, relying on generation of items rather than a preference test. We argue that this new task engages different processing resources, resulting in different patterns of performance. In Experiment 1, invariant learning was demonstrated using a novel fragment completion test. Experiment 2 found that suppressing articulation inhibited learning, implying that this test task accesses phonological knowledge. It is suggested that using the fragment completion test engages different processing resources during test from those in a preference test. Experiment 3 reinforces this position by demonstrating that knowledge appears to transfer across surface features, a result that seems to contradict recent findings by Stadler, Warren, and Lesch (2000). A resolution is offered, drawing on episodic accounts of implicit learning.
Mixed SOC diffusive dynamics as a paradigm for transport in fusion devices
Authors: R. Sánchez  , D.E. Newman  , B.A. Carreras
Published: September 2002

A recently proposed paradigm for understanding turbulent transport dynamics in magnetically confined plasmas, based on the concept of self-organized criticality (SOC), is extended to include the interplay among the many transport mechanisms existing in real plasmas. This extended model might shed some light on the experimentally observed violation at fluctuation scales of the scale invariance condition inherent to the standard SOC model. At the same time, it might provide new experimental tests that could help to validate the possible relevance of the SOC model for understanding turbulent plasma dynamics, since some computations based on a cellular automata realization of such an extended model reveal a dramatic change in the dynamics, with the edge coming to play a dominant role. This might give some hints towards understanding the experimental fact relating good plasma core confinement to a good conditioning of the edge within an SOC paradigm.
“It just goes against the grain.” Public understandings of genetically modified (GM) food in the UK
Authors: Shaw Alison
Published: September 2002

This paper reports on one aspect of qualitative research on public understandings of food risks, focusing on lay understandings of genetically modified (GM) food in a UK context. A range of theoretical, conceptual, and empirical literature on food, risk, and the public understanding of science are reviewed. The fieldwork methods are outlined and empirical data from a range of lay groups are presented. Major themes include: varying “technical” knowledge of science, the relationship between knowledge and acceptance of genetic modification, the uncertainty of scientific knowledge, genetic modification as inappropriate scientific intervention in “nature,” the acceptability of animal and human applications of genetic modification, the appropriate boundaries of scientific innovation, the necessity for GM foods, the uncertainty of risks in GM food, fatalism about avoiding risks, and trust in “experts” to manage potential risks in GM food. Key discussion points relating to a sociological understanding of public attitudes to GM food are raised and some policy implications are highlighted.
Synthesis and characterization of the barium oxalates BaC2O4·0.5H2O, α-BaC2O4 and β-BaC2O4
Authors: Christensen Axel Nørlund , Hazell Rita Grønbæk , Madsen Ian Charles
Published: September 2002

The synthesis of BaC2O4·0.5H2O and its thermal decomposition to α-BaC2O4 and β-BaC2O4 was investigated. BaC2O4·0.5H2O is precipitated at room temperature from aqueous solutions of barium chloride and ammonium oxalate. The deuterated compound BaC2O4·0.5D2O was made in analogy with D2O as the solvent. The compounds were characterized by X-ray and neutron diffraction analysis. Single-crystal X-ray diffraction of BaC2O4·0.5H2O measured at 120 K gave the triclinic cell a = 8.692 (1), b = 9.216 (1), c = 6.146 (1) Å, α = 95.094 (3), β = 95.492 (3), γ = 64.500 (3)°, space group P\bar 1, Z = 4. Two independent Ba atoms are each coordinated to nine O atoms at distances from 2.73 (1) to 2.99 (1) Å. One of the two oxalate ions deviates significantly from planarity. The water molecule does form weak hydrogen bonds. In situ X-ray powder diffraction was used to study the thermal decomposition of BaC2O4·0.5H2O and the formation of α-BaC2O4. The X-ray powder pattern of α-BaC2O4 measured at 473 K was indexed on a triclinic cell with a = 5.137 (3), b = 8.764 (6), c = 9.006 (4) Å, α = 83.57 (4), β = 98.68 (5), γ = 99.53 (5)°, and the space group P\bar 1 with Z = 4.
Terephthalate salts of dipositive cations
Authors: Kaduk James A.
Published: September 2002

The crystal structures of M(C8H4O4)(H2O)2, M = Mg, Mn, Fe and Co, have been determined by applying Monte Carlo simulated annealing techniques to synchrotron powder diffraction data and refined by the Rietveld method using both synchrotron and laboratory powder data. These isostructural compounds crystallize in the monoclinic space group C2/c, with 18.2734 (9) ≤ a ≤ 18.7213 (13), 6.5186 (13) ≤ b ≤ 6.5960 (4), 7.2968 ≤ c ≤ 7.4034 (6) Å, 98.653 (2) ≤ β ≤ 99.675 (1)° and Z = 4. The structure consists of alternating layers (perpendicular to a) of terephthalate anions and octahedrally coordinated metal cations. The octahedra are isolated; each carboxylate bridges two metal cations. The equatorial metal coordination consists of four terephthalate O atoms and there are two axial water molecules. Both water-molecule H atoms participate in normal-strength hydrogen bonds to carboxylate O atoms. Quantum chemical calculations (using CASTEP) were used to determine the H-atom positions and analyze the hydrogen bonding and the metal coordination. Both the atomic charges and the M—O bond-overlap populations indicate that, despite the fact that these compounds are isostructural, the metal–terephthalate bonding is different. The bonding in the Mg complex is essentially ionic, while the M—O bonds in the Mn, Fe and Co complexes have significant covalent character. Comparison of a new Rietveld refinement of the structure of copper(II) terephthalate trihydrate with the reported single-crystal structure provides an opportunity to assess the accuracy and precision that can be expected from structures of aromatic carboxylates determined using X-ray powder data. The average difference between the bond distances in the two structures is 0.03 Å and the average difference in bond angles is only 1.1°.
Predictable close-packing similarities between cis- and trans-2-hydroxy-1-cyclooctanecarboxylic acids and trans-2-hydroxy-1-cyclooctanecarboxamide
Authors: Kálmán Alajos , Fábián László , Argay Gyula , Bernáth Gábor , Gyarmati Zsuzsanna
Published: September 2002

In order to extend the experimental data already available on the close packing of cyclopentanes substituted with vicinal COX (X = OH, NH2) and OH groups to the analogous cyclohexanes, cycloheptanes and cyclooctanes, (1R*,2S*)-cis-2-hydroxy-1-cyclooctanecarboxylic acid (8C), (1R*,2R*)-trans-2-hydroxy-1-cyclooctanecarboxylic acid (8T) and (1R*,2R*)-trans-2-hydroxy-1-cyclooctanecarboxamide (8T*) were subjected to X-ray crystal structure analysis. In 8T and 8T*, the hydrogen bonds form infinite ribbons of dimers joined by R ^{2}_{2}(12) rings with C

i
symmetry. Two types of dimer alternate along each ribbon. The dimers differ in the donor and acceptor roles of the functional groups. This pattern was previously deduced topologically among the possible forms of association for heterochiral dimers [Kálmán et al. (2002). Acta Cryst. B58, 494–501]. As they have the same pattern of hydrogen bonds, 8T and 8T* are isostructural. The additional donor (i.e. the second hydrogen of the NH2 group) present in 8T* links the adjacent ribbons so as to form smaller R^{2} _{2}(8) rings between them. The crystals of the cis stereoisomer 8C are built up from antiparallel hydrogen-bonded helices. The topology and symmetry of this structure are the same as for the close packing of (1R*,2R*,4S*)-4-tert-butyl-2-hydroxy-1-cyclopentanecarboxamide [Kálmán et al. (2001). Acta Cryst. B57, 539–550]; only the hydrogen-bond donors and acceptors are interchanged, in the same way as in the two dimer types of 8T and 8T* ribbons. This analogy suggests that helices may originate as homochiral dimers with C
2 symmetry and polymerize into helices during crystal formation. The conformational characteristics of the heterochiral dimers observed in the title compounds and in closely related structures are discussed.
Ferrocene-1,1′-dicarboxylic acid as a building block in supramolecular chemistry: supramolecular structures in one, two and three dimensions
Authors: Zakaria Choudhury M. , Ferguson George , Lough Alan J. , Glidewell Christopher
Published: September 2002

The supramolecular structures have been determined for nine adducts formed between organic diamines and ferrocene-1,1′-dicarboxylic acid. In the salt-like 1:1 adduct (1) formed with methylamine, the supramolecular structure is one-dimensional, whereas in the 1:1 adducts formed with 1,4-diazabicyclo[2.2.2]octane, (2), and 4,4′-bipyridyl, (4), and in the hydrated 2:1 adduct (3) formed with morpholine, the hard hydrogen bonds form one-dimensional structures, which are expanded to two dimensions by soft C—H...O hydrogen bonds. The hard hydrogen bonds generate two-dimensional structures in the 2:1 adduct (5) formed with octylamine, where the ferrocene component lies across a centre of inversion, in the 1:1 adduct (6) formed with piperidine and in the tetrahydrofuran-solvated 1:1 adduct (7) formed with di(cyclohexyl)amine. In the 2:3 adduct (8) formed by tris-(2-aminoethyl)amine, and in the 2:1 adduct (9) formed with 2-(4′-hydroxyphenyl)ethylamine (tyramine), where Z′ = 1.5 in space group P\bar{1}, the hard hydrogen bonds generate three-dimensional structures. No H transfer from O to N occurs in (4) and only partial transfer of H occurs in (2); in (1), (6) and (7), one H is transferred to N from each acid molecule, and in (3), (5), (8) and (9), two H are transferred from each acid molecule.