bluuebunny/crossref_metadata_2025 huggingface dataset:
Contactless transport of acoustically levitated particles
Authors: Bjelobrk Nada , Foresti Daniele , Dorrestijn Marko , Nabavi Majid , Poulikakos Dimos
Published: October 2010

We present herein a method for the acoustic translation of solid particles of waterlike density in air, by employing a single transducer and controlling the pressure field through regulation of the distance between the reflector and the radiating plate. The levitation and translation of polystyrene particles over a length of 37 mm (approximately 37 particle diameters) were experimentally demonstrated, numerically modeled, and explained. The results of the model show quantitatively how the acoustic pressure distribution inside the levitator chamber and the position of the potential nodes depend on the distance between reflector and radiating plate when the plate is driven in a flexural resonance mode. This phenomenon significantly extends the range of applications of acoustic levitation.
Reverse Schottky-asymmetry spin current detectors
Authors: Lu Yuan , Appelbaum Ian
Published: October 2010

By reversing the Schottky barrier-height asymmetry in hot-electron semiconductor-metal-semiconductor ballistic spin filtering spin detectors, we have achieved the following: (1) demonstration of >50% spin polarization in silicon, resulting from the increase of detection efficiency by elimination of the ferromagnet/silicon interface on the transport channel detector contact and (2) evidence of spin transport at temperatures as high as 260 K, enabled by an increase in detector Schottky barrier height.
Femtosecond UV-pump/visible-probe measurements of carrier dynamics in stacked graphene films
Authors: Shang Jingzhi , Luo Zhiqiang , Cong Chunxiao , Lin Jianyi , Yu Ting , Gurzadyan Gagik G.
Published: October 2010

The transient differential transmission (ΔT/T) spectra of graphene were obtained from 380 (3.3 eV) to 670 nm (1.9 eV). The intraband carrier equilibration by carrier–carrier scattering occurred within 60 fs. The subsequent carrier relaxation process was governed by carrier-optical phonon scattering and had linear dependence on the probe photon energy (Epr); lifetimes ranged from 180 to 90 fs for Epr from 2.1 to 2.8 eV. Negative ΔT/T signals in kinetic curves were discussed and assigned to thermal diffusion and shrinkage of band separation caused by lattice heating.
Using femtosecond laser to fabricate highly precise interior three-dimensional microstructures in polymeric flow chip
Authors: Lee Chia-Yu , Chang Ting-Chou , Wang Shau-Chun , Chien Chih-Wei , Cheng Chung-Wei
Published: October 2010

This paper reports using femtosecond laser marker to fabricate the three-dimensional interior microstructures in one closed flow channel of plastic substrate. Strip-like slots in the dimensions of 800 μm×400 μm×65 μm were ablated with pulse Ti:sapphire laser at 800 nm (pulse duration of ∼120 fs with 1 kHz repetition rate) on acrylic slide. After ablation, defocused beams were used to finish the surface of microstructures. Having finally polished with sonication, the laser fabricated structures are highly precise with the arithmetic roughness of 1.5 and 4.5 nm. Fabricating such highly precise microstructures cannot be accomplished with nanosecond laser marking or other mechanical drilling methods. In addition, since laser ablation can directly engrave interior microstructures in one closed chip, glue smearing problems to damage molded microstructures possibly to occur during the chip sealing procedures can be avoided too.
Attachment cross sections of protonated water clusters
Authors: Zamith Sébastien , Feiden Pierre , Labastie Pierre , L’Hermite Jean-Marc
Published: October 2010

The attachment of water molecules onto size selected protonated water clusters has been experimentally investigated. Absolute attachment cross sections are measured as a function of cluster size, collision energy, and initial cluster temperature. Although thermal evaporation is ruled out in our experiment, attachment cross sections become significantly smaller than hard sphere cross sections as the collision energy increases. This feature is attributed to a transition from adiabatic to nonadiabatic regime. It is shown to be due to a dynamical effect: as the collision duration becomes shorter than the typical time required for collision energy redistribution into clusters internal energy, the attachment probability is reduced. We relate this typical time to the period of the main surface vibrational mode excited by the collisions. This hypothesis is further supported by results obtained with deuterated water clusters.
Comparative efficiency of subcellular targeting signals for expression of a toxic protein in sugarcane
Authors: Jackson Mark A. , Nutt Kerry A. , Hassall Rachael , Rae Anne L.
Published: October 2010

Transgenic sugarcane plants (Saccharum hybrid) have been proposed as a production platform for recombinant proteins, including those providing pathogen resistance as well as high value therapeutic proteins. For the in planta production of proteins that are potentially toxic, a careful consideration of subcellular location is required in order to optimise yield and to avoid detrimental interaction with plant cellular processes. In this study, avidin, a glycoprotein that is potentially toxic to cells because of its high affinity to the co-vitamin biotin, was used to test the effectiveness of a range of targeting signals. Accumulation of avidin was directed to the apoplast, endoplasmic reticulum and to the lytic and delta type vacuoles. Although targeting to the delta vacuole resulted in the highest yields of avidin, these plants developed a biotin deficient phenotype, indicating that this targeting was not fully effective in protecting cellular biotin pools. Similar problems were also observed when avidin was retained in the endoplasmic reticulum. When avidin was targeted to the lytic vacuole using the targeting signal from the sugarcane legumain, plants remained phenotypically normal; however, avidin was predominantly detected as a degraded product due to site-specific limited proteolysis in the vacuole. For avidin and other potentially toxic products, this lytic vacuole targeting signal may be useful if stability within this proteolytic environment can be improved.
Quantifying genetic effects of ground cover on soil water evaporation using digital imaging
Authors: Mullan Daniel J. , Reynolds Matthew P.
Published: October 2010

Rapid development of leaf area and/or aboveground biomass has the potential to improve water harvest of rain fed wheat in Mediterranean-type environments through reduced soil evaporation. However, quantitative relationships between genetic differences in early ground cover and soil water evaporation have not been established. Furthermore, accurate phenotyping of ground cover and early vigour have typically been achieved via destructive sampling methods, which are too time-consuming to undertake within breeding programs. Digital image analysis has previously been identified as an alternative indirect method of analysis, whereby computer analysis is ued to determine percentage ground cover. This study uses a digital ground cover (DGC) analysis tool for high throughput screening of four large wheat populations. The DGC methodology was validated via comparisons with alternative measures of canopy cover, such as normalised difference vegetation index (NDVI) (r2 = 0.69), biomass (r2 = 0.63), leaf area index (r2 = 0.80) and light penetration through the canopy (r2 = 0.70). The wheat populations were utilised to estimate the potential variation in soil evaporation associated with genetic differences in early ground cover, which was validated using established models. Estimates of genetic differences in soil evaporation within the four populations (6.90–24.8 mm) suggest that there is sufficient genetic variation to increase water harvest through targeting faster ground cover. Implications for improved wheat yields and breeding are discussed.
Effect of light and CO2 on inorganic carbon uptake in the invasive aquatic CAM-plant Crassula helmsii
Authors: Klavsen Signe Koch , Maberly Stephen C.
Published: October 2010

Crassula helmsii (T. Kirk) Cockayne is an invasive aquatic plant in Europe that can suppress many native species because it can grow at a large range of dissolved inorganic carbon concentrations and light levels. One reason for its ecological success may be the possession of a regulated Crassulacean Acid Metabolism (CAM), which allows aquatic macrophytes to take up CO2 in the night in addition to the daytime. The effect of light and CO2 on the regulation of CAM and photosynthesis in C. helmsii was investigated to characterise how physiological acclimation may confer this ecological flexibility. After 3 weeks of growth at high light (230 µmol photon m–2 s–1), C. helmsii displayed 2.8 times higher CAM at low compared with high CO2 (22 v. 230 mmol m–3). CAM was absent in plants grown at low light (23 µmol photon m–2 s–1) at both CO2 concentrations. The observed regulation patterns are consistent with CAM acting as a carbon conserving mechanism. For C. helmsii grown at high light and low CO2, mean photosynthetic rates were relatively high at low concentrations of CO2 and were on average 80 and 102 µmol O2 g–1 DW h–1 at CO2 concentrations of 3 and 22 mmol m–3 CO2, which, together with mean final pH values of 9.01 in the pH drift, indicate a low CO2 compensation point (<3 mmol m–3) but do not indicate use of bicarbonate as an additional source of exogenous inorganic carbon. The relatively high photosynthetic rates during the entire daytime were caused by internally derived CAM-CO2 and uptake from the external medium. During decarboxylation, CO2 generated from CAM contributed up to 29% to photosynthesis, whereas over a day the contribution to the carbon balance was ≤13%. The flexible adjustment of CAM and the ability to maintain photosynthesis at very low external CO2 concentrations, partly by making use of internally generated CO2 via CAM, may contribute to the broad ecological niche of C. helmsii.
Effects of leaf development and phosphorus supply on the photosynthetic characteristics of perennial legume species with pasture potential: modelling photosynthesis with leaf development
Authors: Suriyagoda Lalith D. B. , Lambers Hans , Ryan Megan H. , Renton Michael
Published: October 2010

Age-dependent changes in leaf photosynthetic characteristics (i.e. parameters of the light response curve (maximum photosynthetic rate (Pmax), quantum yield (Φ) and the convexity parameter (θ)), stomatal conductance (gs) and dark respiration rate (Rd)) of an exotic perennial legume, Medicago sativa L. (lucerne), and two potential pasture legumes native to Australia, Cullen australasicum (Schltdl.) J.W. Grime and Cullen pallidum A. Lee, grown in a glasshouse for 5 months at two phosphorus (P) levels (3 (P3) and 30 (P30) mg P kg–1 dry soil) were tested. Leaf appearance rate and leaf area were lower at P3 than at P30 in all species, with M. sativa being the most sensitive to P3. At any leaf age, photosynthetic characteristics did not differ between P treatments. However, Pmax and gs for all the species and Φ for Cullen species increased until full leaf expansion and then decreased. The convexity parameter, θ, did not change with leaf age, whereas Rd decreased. The estimates of leaf net photosynthetic rate (Pleaf) obtained through simulations at variable Pmax and Φ were lower during early and late leaf developmental stages and at lower light intensities than those obtained when Φ was assumed to be constant (e.g. for a horizontally placed leaf, during the 1500°C days developmental period, 3 and 19% reduction of Pleaf at light intensities of 1500 and 500 µmol m–2 s–1, respectively). Therefore, developmental changes in leaf photosynthetic characteristics should be considered when estimating and simulating Pleaf of these pasture species.
Effects of fruiting on vegetative growth and development dynamics of grapevines (Vitis vinifera cv. Semillon) can be traced back to events at or before budbreak
Authors: Greer Dennis H. , Weston Chris
Published: October 2010

Leaf and shoot growth and development patterns in Vitis vinifera L. cv. Semillon were analysed dynamically. Potted fruiting and vegetative vines were grown in controlled conditions and budbreak, leaf and internode (metamers) appearance and expansion were measured. Buds were also dissected microscopically. Metamer appearance occurred in three zones; the first 5–6 metamers emerged as a cluster with fastest expansion and largest size. Marked differences in sizes and dynamics of growth occurred between fruiting and vegetative vines because flowers were absent. The next 13–14 preformed metamers appeared at a constant rate and metamer size declined along the shoot. Timing of maximum expansion and duration of growth of the metamers in this cohort was increasingly delayed in fruiting compared with vegetative vines. Beyond node 20, neoformed metamers emerged at a slow constant rate and were smallest overall. Throughout development, extension of the internode occurred before expansion of the subtending leaf, consistent with the liana habit of grapevines. Differences between fruiting and vegetative vines in metamer development were observed just after budbreak and these differences generally appreciated over time. The impact of reproduction on vegetative growth can, therefore, likely be attributed to competition for carbohydrate between floral and leaf primordia in the dormant or breaking bud, accounting for the smaller leaves and internodes.
A unique web resource for physiology, ecology and the environmental sciences: PrometheusWiki
Authors: Sack Lawren , Cornwell Will K. , Santiago Louis S. , Barbour Margaret M. , Choat Brendan , Evans John R. , Munns Rana , Nicotra Adrienne
Published: October 2010

PROtocols, METHods, Explanations and Updated Standards Wiki (PrometheusWiki, http://www.publish.csiro.au/prometheuswiki/) is a new open access, fully searchable web resource that contains protocols and methods for plant physiology, ecology and environmental sciences. Contributions can be uploaded by anyone in the community, with attributed authorship, and are open for wiki-style comment. This resource allows the gathering in one place of methods, links to published methods and detailed protocols used by leading laboratories around the world, with annotation. As a web resource, PrometheusWiki is continually evolving and updatable, easily and rapidly searchable and highly accessible. It will also enhance communication, allowing multimedia description of protocols and techniques, with spreadsheet tools, slide shows and video files easily integrated into the text. This resource is anticipated to lead to strong benefits in standardising methods, improving access to training for students and professionals, promoting collaborations and expanding the cutting edge of research.
Linguistic Self‐Correction in the Absence of Feedback: A New Approach to the Logical Problem of Language Acquisition
Authors: Ramscar Michael , Yarlett Daniel
Published: October 2010

In a series of studies children show increasing mastery of irregular plural forms (such as mice) simply by producing erroneous over‐regularized versions of them (such as mouses). We explain this phenomenon in terms of successive approximation in imitation: Children over‐regularize early in acquisition because the representations of frequent, regular plural forms develop more quickly, such that at the earliest stages of production they interfere with children's attempts to imitatively reproduce irregular forms they have heard in the input. As the strength of the representations that determine children's productions settle asymptotically, the early advantage for the frequent regular forms is negated, and children's attempts to imitate the irregular forms they have observed become more likely to succeed (a process that produces the classic U‐shape in children's acquisition of plural inflection). These data show that children can acquire correct linguistic behavior without feedback in a situation where, as a result of philosophical and linguistic analyses, it has often been argued that it is logically impossible for them to do so.
Foundations of Representation: Where Might Graphical Symbol Systems Come From?
Authors: Garrod Simon , Fay Nicolas , Lee John , Oberlander Jon , MacLeod Tracy
Published: October 2010

It has been suggested that iconic graphical signs evolve into symbolic graphical signs through repeated usage. This article reports a series of interactive graphical communication experiments using a ‘pictionary’ task to establish the conditions under which the evolution might occur. Experiment 1 rules out a simple repetition based account in favor of an account that requires feedback and interaction between communicators. Experiment 2 shows how the degree of interaction affects the evolution of signs according to a process of grounding. Experiment 3 confirms the prediction that those not involved directly in the interaction have trouble interpreting the graphical signs produced in Experiment 1. On the basis of these results, this article argues that icons evolve into symbols as a consequence of the systematic shift in the locus of information from the sign to the users' memory of the sign's usage supported by an interactive grounding process.
Mnemonic Context Effect in Two Cultures: Attention to Memory Representations?
Authors: Duffy Sean , Kitayama Shinobu
Published: October 2010

In two experiments we demonstrate a substantial cross‐cultural difference in a mnemonic context effect, whereby a magnitude estimate of a simple stimulus such as a line or circle is biased toward the center of the distribution of previously seen instances of the same class. In support of the hypothesis that Asians are more likely than Americans to disperse their attention to both the target stimulus and its mnemonic context, this effect was consistently larger for Japanese than for Americans. Moreover, the cultural difference was attenuated by an experimentally induced belief in class homogeneity that augmented the context effect itself in both cultures. More important, these belief effects happened in the absence of any objective change in stimulus distribution. Implications for sociocultural shaping of cognition are discussed.
When Are Tutorial Dialogues More Effective Than Reading?
Authors: VanLehn Kurt , Graesser Arthur C. , Jackson G. Tanner , Jordan Pamela , Olney Andrew , Rosé Carolyn P.
Published: October 2010

It is often assumed that engaging in a one‐on‐one dialogue with a tutor is more effective than listening to a lecture or reading a text. Although earlier experiments have not always supported this hypothesis, this may be due in part to allowing the tutors to cover different content than the noninteractive instruction. In 7 experiments, we tested the interaction hypothesis under the constraint that (a) all students covered the same content during instruction, (b) the task domain was qualitative physics, (c) the instruction was in natural language as opposed to mathematical or other formal languages, and (d) the instruction conformed with a widely observed pattern in human tutoring: Graesser, Person, and Magliano's 5‐step frame. In the experiments, we compared 2 kinds of human tutoring (spoken and computer mediated) with 2 kinds of natural‐language‐based computer tutoring (Why2‐Atlas and Why2‐AutoTutor) and 3 control conditions that involved studying texts. The results depended on whether the students' preparation matched the content of the instruction. When novices (students who had not taken college physics) studied content that was written for intermediates (students who had taken college physics), then tutorial dialogue was reliably more beneficial than less interactive instruction, with large effect sizes. When novices studied material written for novices or intermediates studied material written for intermediates, then tutorial dialogue was not reliably more effective than the text‐based control conditions.
Speed, Accuracy, and Serial Order in Sequence Production
Authors: Pfordresher Peter Q. , Palmer Caroline , Jungers Melissa K.
Published: October 2010

The production of complex sequences like music or speech requires the rapid and temporally precise production of events (e.g., notes and chords), often at fast rates. Memory retrieval in these circumstances may rely on the simultaneous activation of both the current event and the surrounding context (). We describe an extension to a model of incremental retrieval in sequence production () that incorporates this logic to predict overall error rates and speed—accuracy trade‐offs, as well as types of serial ordering errors. The model—assumes that retrieval of the current event is influenced by activations of surrounding events. Activations of surrounding events increase over time, such that both the accessibility of distant events and overall accuracy increases at slower production rates. The model's predictions were tested in an experiment in which pianists performed unfamiliar music at 8 different tempi. Model fits to speed—accuracy data and to serial ordering errors support model predictions. Parameter fits to individual data further suggest that working memory contributes to the retrieval of serial order and overall accuracy is influenced in addition by motor dexterity and domain‐specific skill.
Explaining Color Term Typology With an Evolutionary Model
Authors: Dowman Mike
Published: October 2010

An expression‐induction model was used to simulate the evolution of basic color terms to test Berlin and Kay's (1969) hypothesis that the typological patterns observed in basic color term systems are produced by a process of cultural evolution under the influence of biases resulting from the special properties of universal focal colors. Ten agents were simulated, each of which could learn color term denotations by generalizing from examples using Bayesian inference, and for which universal focal red, yellow, green, and blue were especially salient, but unevenly spaced in the perceptual color space. Conversations between these agents, in which agents would learn from one another, were simulated over several generations, and the languages emerging at the end of each simulation were investigated. The proportion of color terms of each type correlated closely with the equivalent frequencies found in the World Color Survey, and most of the emergent languages could be placed on one of the evolutionary trajectories proposed by . The simulation therefore demonstrates how typological patterns can emerge as a result of learning biases acting over a period of time.
Formal Distinctiveness of High‐ and Low‐Imageability Nouns: Analyses and Theoretical Implications
Authors: Reilly Jamie , Kean Jacob
Published: October 2010

Words associated with perceptually salient, highly imageable concepts are learned earlier in life, more accurately recalled, and more rapidly named than abstract words (R. W. ; ). Theories accounting for this concreteness effect have focused exclusively on semantic properties of word referents. A novel possibility is that word structure may also contribute to the effect. We report a corpus‐based analysis of the phonological and morphological structures of a large set of nouns with imageability ratings (N = 2,023). High‐ and low‐imageability nouns differed by length, etymology, prosody, affixation, phonological neighborhood density, and rates of consonant clustering. On average, nouns denoting abstract concepts were longer, more derivationally complex, and emerged in English from a different distribution of languages than did concrete nouns. We address implications for interactivity of word form and meaning as pertain to theories of word concreteness, lexical acquisition, and word processing.
Language‐Relative Construal of Individuation Constrained by Universal Ontology: Revisiting Language Universals and Linguistic Relativity
Authors: Imai Mutsumi , Mazuka Reiko
Published: October 2010

Objects and substances bear fundamentally different ontologies. In this article, we examine the relations between language, the ontological distinction with respect to individuation, and the world. Specifically, in cross‐linguistic developmental studies that follow , we examine the question of whether language influences our thought in different forms, like (1) whether the language‐specific construal of entities found in a word extension context () is also found in a nonlinguistic classification context; (2) whether the presence of labelsper se, independent of the count‐mass syntax, fosters ontology‐based classification; (3) in what way, if at all, the count‐mass syntax that accompanies a label changes English speakers' default construal of a given entity?

On the basis of the results, we argue that the ontological distinction concerning individuation is universally shared and functions as a constraint on early learning of words. At the same time, language influences one's construal of entities cross‐lingistically and developmentally, and causes a temporary change of construal within a single language. We provide a detailed discussion of how each of these three ways language may affect the construal of entities, and discuss how our universally possessed knowledge interacts with language both within a single language and in cross‐linguistic context.
Contextualizing Counterintuitiveness: How Context Affects Comprehension and Memorability of Counterintuitive Concepts
Authors: Upala M. Afzal , Gonce Lauren O. , Tweney Ryan D. , Slone D. Jason
Published: October 2010

A number of anthropologists have argued that religious concepts are minimally counterintuitive and that this gives them mnemic advantages. This paper addresses the question of why people have the memory architecture that results in such concepts being more memorable than other types of concepts by pointing out the benefits of a memory structure that leads to better recall for minimally counterintuitive concepts and by showing how such benefits emerge in the real‐time processing of comprehending narratives such as folk tales. This model suggests that memorability is not an inherent property of a concept; rather it is a property of the concept, the context in which the concept is presented, and the background knowledge that the comprehendor possesses about the concept. The model predicts how memorability of a concept should change if the context containing the concept were changed. The paper also presents the results of experiments carried out to test these predictions.
The Role of Falsification in the Development of Cognitive Architectures: Insights from a Lakatosian Analysis
Authors: Cooper Richard P.
Published: October 2010

It has been suggested that the enterprise of developing mechanistic theories of the human cognitive architecture is flawed because the theories produced are not directly falsifiable. Newell attempted to sidestep this criticism by arguing for a Lakatosian model of scientific progress in which cognitive architectures should be understood as theories that develop over time. However, Newell's own candidate cognitive architecture adhered only loosely to Lakatosian principles. This paper reconsiders the role of falsification and the potential utility of Lakatosian principles in the development of cognitive architectures. It is argued that a lack of direct falsifiability need not undermine the scientific development of a cognitive architecture if broadly Lakatosian principles are adopted. Moreover, it is demonstrated that the Lakatosian concepts of positive and negative heuristics for theory development and of general heuristic power offer methods for guiding the development of an architecture and for evaluating the contribution and potential of an architecture's research program.
Dynamic Self‐Organization and Early Lexical Development in Children
Authors: Li Ping , Zhao Xiaowei , Mac Whinney Brian
Published: October 2010

In this study we present a self‐organizing connectionist model of early lexical development. We call this model DevLex‐II, based on the earlier DevLex model. DevLex‐II can simulate a variety of empirical patterns in children's acquisition of words. These include a clear vocabulary spurt, effects of word frequency and length on age of acquisition, and individual differences as a function of phonological short‐term memory and associative capacity. Further results from lesioned models indicate developmental plasticity in the network's recovery from damage, in a non‐monotonic fashion. We attribute the network's abilities in accounting for lexical development to interactive dynamics in the learning process. In particular, variations displayed by the model in the rate and size of early vocabulary development are modulated by (a) input characteristics, such as word frequency and word length, (b) consolidation of lexical‐semantic representation, meaning‐form association, and phonological short‐term memory, and (c) delayed processes due to interactions among timing, severity, and recoverability of lesion. Together, DevLex and DevLex‐II provide an accurate computational account of early lexical development.
A Computational Model of Event Segmentation From Perceptual Prediction
Authors: Reynolds Jeremy R. , Zacks Jeffrey M. , Braver Todd S.
Published: October 2010

People tend to perceive ongoing continuous activity as series of discrete events. This partitioning of continuous activity may occur, in part, because events correspond to dynamic patterns that have recurred across different contexts. Recurring patterns may lead to reliable sequential dependencies in observers' experiences, which then can be used to guide perception. The current set of simulations investigated whether this statistical structure within events can be used 1) to develop stable internal representations that facilitate perception and 2) to learn when to update such representations in a self‐organizing manner. These simulations demonstrate that experience with recurring patterns enables a system to accurately predict upcoming stimuli within an event, to identify boundaries between such events based on transient increases in prediction error, and to use such boundaries to improve prediction about subsequent activities.
Understanding the Emergence of Modularity in Neural Systems
Authors: Bullinaria John A.
Published: October 2010

Modularity in the human brain remains a controversial issue, with disagreement over the nature of the modules that exist, and why, when, and how they emerge. It is a natural assumption that modularity offers some form of computational advantage, and hence evolution by natural selection has translated those advantages into the kind of modular neural structures familiar to cognitive scientists. However, simulations of the evolution of simplified neural systems have shown that, in many cases, it is actually non‐modular architectures that are most efficient. In this paper, the relevant issues are discussed and a series of simulations are presented that reveal crucial dependencies on the details of the learning algorithms and tasks that are being modelled, and the importance of taking into account known physical brain constraints, such as the degree of neural connectivity. A pattern is established which provides one explanation of why modularity should emerge reliably across a range of neural processing tasks.
Recursion, Language, and Starlings
Authors: Corballis Michael C.
Published: October 2010

It has been claimed that recursion is one of the properties that distinguishes human language from any other form of animal communication. Contrary to this claim, a recent study purports to demonstrate center‐embedded recursion in starlings. I show that the performance of the birds in this study can be explained by a counting strategy, without any appreciation of center‐embedding. To demonstrate that birds understand center‐embedding of sequences of the form AnBn (such as A1A2B2B1, or A3A4A5B5B4B3) would require not only that they discriminate such patterns from other patterns, but that they appreciate that elements must be bound from the outside in (thus, in the above examples, A1B1, A2B2, A3B3, A4B4, A5B5 are bound pairs). This has not been shown in nonhuman species, and sentences with this structure are difficult even for humans to parse. There appears to be no evidence to date that nonhuman species understand recursion.
Attention to Endpoints: A Cross‐Linguistic Constraint on Spatial Meaning
Authors: Regier Terry , Zheng Mingyu
Published: October 2010

We investigate a possible universal constraint on spatial meaning. It has been proposed that people attend preferentially to the endpoints of spatial motion events, and that languages may therefore make finer semantic distinctions at event endpoints than at event beginnings. We test this proposal. In Experiment 1, we show that people discriminate the endpoints of spatial motion events more readily than they do event beginnings—suggesting a non‐linguistic attentional bias toward endpoints. In Experiment 2, speakers of Arabic, Chinese, and English each described a set of spatial events displayed in video clips. Although the spatial systems of these languages differ, speakers of all three languages made finer semantic distinctions at event endpoints, compared to event beginnings. These findings are consistent with the proposal that event endpoints are privileged over event beginnings, in both language and perception.
Jiahuai Han: Aflame on inflammation and p38
Authors: Sedwick Caitlin
Published: October 2010

Han studies the mechanisms of inflammation and immunity, and the many cellular functions of p38.
Cep120 is asymmetrically localized to the daughter centriole and is essential for centriole assembly
Authors: Mahjoub Moe R. , Xie Zhigang , Stearns Tim
Published: October 2010

Centrioles form the core of the centrosome in animal cells and function as basal bodies that nucleate and anchor cilia at the plasma membrane. In this paper, we report that Cep120 (Ccdc100), a protein previously shown to be involved in maintaining the neural progenitor pool in mouse brain, is associated with centriole structure and function. Cep120 is up-regulated sevenfold during differentiation of mouse tracheal epithelial cells (MTECs) and localizes to basal bodies. Cep120 localizes preferentially to the daughter centriole in cycling cells, and this asymmetry between mother and daughter centrioles is relieved coincident with new centriole assembly. Photobleaching recovery analysis identifies two pools of Cep120, differing in their halftime at the centriole. We find that Cep120 is required for centriole duplication in cycling cells, centriole amplification in MTECs, and centriole overduplication in S phase–arrested cells. We propose that Cep120 is required for centriole assembly and that the observed defect in neuronal migration might derive from a defect in this process.
Cdc20 hypomorphic mice fail to counteract de novo synthesis of cyclin B1 in mitosis
Authors: Malureanu Liviu , Jeganathan Karthik B. , Jin Fang , Baker Darren J. , van Ree Janine H. , Gullon Oliver , Chen Zheyan , Henley John R. , van Deursen Jan M.
Published: October 2010

Cdc20 is an activator of the anaphase-promoting complex/cyclosome that initiates anaphase onset by ordering the destruction of cyclin B1 and securin in metaphase. To study the physiological significance of Cdc20 in higher eukaryotes, we generated hypomorphic mice that express small amounts of this essential cell cycle regulator. In this study, we show that these mice are healthy and not prone to cancer despite substantial aneuploidy. Cdc20 hypomorphism causes chromatin bridging and chromosome misalignment, revealing a requirement for Cdc20 in efficient sister chromosome separation and chromosome–microtubule attachment. We find that cyclin B1 is newly synthesized during mitosis via cytoplasmic polyadenylation element–binding protein-dependent translation, causing its rapid accumulation between prometaphase and metaphase of Cdc20 hypomorphic cells. Anaphase onset is significantly delayed in Cdc20 hypomorphic cells but not when translation is inhibited during mitosis. These data reveal that Cdc20 is particularly rate limiting for cyclin B1 destruction because of regulated de novo synthesis of this cyclin after prometaphase onset.
Cell shape and contractility regulate ciliogenesis in cell cycle–arrested cells
Authors: Pitaval Amandine , Tseng Qingzong , Bornens Michel , Théry Manuel
Published: October 2010

In most lineages, cell cycle exit is correlated with the growth of a primary cilium. We analyzed cell cycle exit and ciliogenesis in human retinal cells and found that, contrary to the classical view, not all cells exiting the cell division cycle generate a primary cilium. Using adhesive micropatterns to control individual cell spreading, we demonstrate that cell spatial confinement is a major regulator of ciliogenesis. When spatially confined, cells assemble a contractile actin network along their ventral surface and a protrusive network along their dorsal surface. The nucleus–centrosome axis in confined cells is oriented toward the dorsal surface where the primary cilium is formed. In contrast, highly spread cells assemble mostly contractile actin bundles. The nucleus–centrosome axis of spread cells is oriented toward the ventral surface, where contractility prevented primary cilium growth. These results indicate that cell geometrical confinement affects cell polarity via the modulation of actin network architecture and thereby regulates basal body positioning and primary cilium growth.
MyoD regulates apoptosis of myoblasts through microRNA-mediated down-regulation of Pax3
Authors: Hirai Hiroyuki , Verma Mayank , Watanabe Shuichi , Tastad Christopher , Asakura Yoko , Asakura Atsushi
Published: October 2010

The molecules that regulate the apoptosis cascade are also involved in differentiation and syncytial fusion in skeletal muscle. MyoD is a myogenic transcription factor that plays essential roles in muscle differentiation. We noticed that MyoD−/− myoblasts display remarkable resistance to apoptosis by down-regulation of miR-1 (microRNA-1) and miR-206 and by up-regulation of Pax3. This resulted in transcriptional activation of antiapoptotic factors Bcl-2 and Bcl-xL. Forced MyoD expression induces up-regulation of miR-1 and miR-206 and down-regulation of Pax3, Bcl-2, and Bcl-xL along with increased apoptosis in MyoD−/− myoblasts. In contrast, MyoD gene knockdown increases cell survival of wild-type myoblasts. The 3′ untranslated region of Pax3 mRNA contains two conserved miR-1/miR-206–binding sites, which are required for targeting of these microRNAs (miRNAs). Therefore, these data suggest that MyoD not only regulates terminal differentiation but also apoptosis through miRNA-mediated down-regulation of Pax3. Finally, MyoD, miR-1, and miR-206 are all down-regulated in quiescent satellite cells, which may be required for maintenance of muscle stem cells.
Asymmetry, Partial Moments, and Production Risk
Authors: Antle john M.
Published: October 2010

Partial‐moment functions are proposed as a flexible way to characterize and estimate asymmetric effects of inputs on output distributions. Methods for econometric estimation of partial‐moment functions, and tests for input symmetry and location‐scale distributions, are presented. A Monte Carlo study demonstrates properties of proposed tests. A study of Ecuadorian potato production illustrates the methods. Hypotheses of input symmetry and location scale are rejected. A risk‐value model based on partial moments implies that fertilizer is risk increasing and fungicides and labor are risk reducing in potato production, whereas an expected utility model based on full moments has the opposite implications.
Relationship between right ventricular volumes measured by cardiac magnetic resonance imaging and prognosis in patients with chronic heart failure
Authors: Bourantas Christos V. , Loh Huan P. , Bragadeesh Thanjavur , Rigby Alan S. , Lukaschuk Elena I. , Garg Scot , Tweddel Ann C. , Alamgir Farqad M. , Nikitin Nikolay P. , Clark Andrew L. , Cleland John G.F.
Published: October 2010

Aims

The aim of this study was to investigate the prognostic impact of right ventricular (RV) size in patients with chronic heart failure.

Methods and results

Normal volunteers (n = 80) and patients (n = 380) with left ventricular (LV) ejection fraction <45% on echocardiography and on optimal treatment for heart failure underwent cardiac magnetic resonance imaging with measurement of LV and RV volumes, mass and ejection fraction. The mean and the standard deviation (SD) of the RV end‐systolic volume index in normal subjects were used to define the normal range as: mean RV end‐systolic volume index +2 SD. Patients with dilated RV (>2 SD beyond the mean) (25%) had more frequent evidence of fluid overload in clinical examination and greater LV dimensions (P < 0.0001). During follow‐up (median 45, interquartile range: 28–66 months), 37% of patients with and 24% without RV dilation died (log‐rank test = 8.4; P = 0.004). In a multivariable Cox regression model, including 13 other clinical variables, RV (HR: 1.08/10 mL/m2, 95% CI: 1.00–1.18, P = 0.044), but not LV, end‐systolic volume index predicted a worse outcome.

Conclusion

Twenty‐five per cent of patients with heart failure due to LV systolic dysfunction have a dilated right ventricle. Greater RV dimensions predict mortality in patients with chronic heart failure. Treatments aimed at preserving or enhancing RV structure and function, possibly by unloading the RV by reducing pulmonary vascular resistance or left atrial pressure, should be investigated.
High‐energy phosphotransfer in the failing mouse heart: role of adenylate kinase and glycolytic enzymes
Authors: Aksentijević Dunja , Lygate Craig A. , Makinen Kimmo , Zervou Sevasti , Sebag‐Montefiore Liam , Medway Debra , Barnes Hannah , Schneider Jurgen E. , Neubauer Stefan
Published: October 2010

Aims

To measure the activity of the key phosphotransfer enzymes creatine kinase (CK), adenylate kinase (AK), and glycolytic enzymes in two common mouse models of chronic heart failure.

Methods and results

C57BL/6 mice were subjected to transverse aortic constriction (TAC), myocardial infarction induced by coronary artery ligation (CAL), or sham operation. Activities of phosphotransfer enzymes CK, AK, glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH), 3‐phosphoglycerate kinase (PGK), and pyruvate kinase were assessed spectrophotometrically. Mice were characterized by echocardiography or magnetic resonance imaging 5‐ to 8‐week post‐surgery and selected for the presence of congestive heart failure. All mice had severe left ventricular hypertrophy, impaired systolic function and pulmonary congestion compared with sham controls. A significant decrease in myocardial CK and maximal CK reaction velocity was observed in both experimental models of heart failure. However, the activity of AK and its isoforms remained unchanged, despite a reduction in its protein expression. In contrast, the activities of glycolytic phosphotransfer mediators GAPDH and PGK were 19 and 12% higher in TAC, and 31 and 23% higher in CAL models, respectively.

Conclusion

Chronic heart failure in the mouse is characterized by impaired CK function, unaltered AK, and increased activity of glycolytic phosphotransfer enzymes. This pattern of altered phosphotransfer activity was observed independent of the heart failure aetiology.
Non‐selective vs. selective beta‐blocker treatment and the risk of thrombo‐embolic events in patients with heart failure
Authors: de Peuter Olav R. , Souverein Patrick C. , Klungel Olaf H. , Büller Harry R. , de Boer Anthonius , Kamphuisen Pieter W.
Published: October 2010

Aims

Heart failure (HF) is associated with a prothrombotic state, resulting in an increased risk for thrombo‐embolic events. Studies suggest a reduced prothrombotic state when non‐selective beta‐blockers relative to selective beta‐blockers are given. We studied the influence of non‐selective beta‐blockers compared with selective beta‐blockers on the occurrence of arterial and venous thrombo‐embolic events in patients with HF.

Methods and results

Data were obtained from the PHARMO Record Linkage System, a population‐based registry of pharmacy records linked with hospital discharge records in The Netherlands. In the period of 1998–2007, 20 870 patients were hospitalized for HF. We used Cox regression analysis with time‐varying beta‐blocker covariate to assess the difference in the incidence of thrombo‐embolic events [acute coronary syndrome (ACS), stroke, or pulmonary embolism] among patients. Median follow‐up was 2.0 years (inter‐quartile range: 0.7–4.1). Directly after discharge, 6558 patients were prescribed a selective beta‐blocker and 2202 patients a non‐selective beta‐blocker. The hazard ratio (HR) for any thrombo‐embolic event for non‐selective beta‐blockers compared with selective beta‐blockers was 0.76 [95% confidence interval (CI): 0.64–0.89]. After adjustment, the difference remained (HR 0.84, 95% CI: 0.72–0.99). The effect was most prominent for ACS (HR 0.78, 95% CI: 0.65–0.93), and not clear for stroke (HR 1.00, 95% CI: 0.67–1.50) or pulmonary embolism (HR 1.33, 95% CI: 0.66–2.71).

Conclusion

In patients with HF, the use of non‐selective beta‐blockers was associated with a lower risk of thrombo‐embolic events than selective beta‐blockers. Whether this beneficial effect is caused by the additional beta2‐receptor blockade remains to be elucidated. These findings need to be validated in a well‐designed randomized study.
Innovative strategy for implementing chronic heart failure guidelines among family physicians in different healthcare settings in Berlin
Authors: Braun Vittoria , Heintze Christoph , Rufer Veronika , Welke Justus , Stein Tanja , Mehrhof Felix , Dini Lorena
Published: October 2010

Aims

The aim of this study was to improve drug therapy for chronic heart failure (CHF) patients.

Methods and results

This prospective interventional pilot study was performed with cross‐sectional comparative analysis before and after the intervention. Usual pharmacotherapy was observed for 8 months in two different outpatient healthcare settings in Berlin [11 family physicians from individual GP (IGP) practices and 12 working in a medical care centre (MCC)]. Medical care centres provide a novel structure for outpatient care and have recently been introduced in Germany. The subsequent intervention entailed implementation of heart failure guidelines via a computer‐based reminder system, followed by renewed cross‐sectional observation of prescription behaviour for 1 year. Family physicians recruited patients, assessed CHF severity according to the NYHA class, and referred patients for echocardiography. The study included 190 patients in the baseline phase and 209 in the intervention phase. Longitudinal follow‐up was performed in 172 cases. Echocardiography was ordered by 94.6% of MCC‐physicians and 79.9% of IGP's. Undermedication was observed in both settings. Guideline‐based beta‐blocker therapy was prescribed for 46.3% of patients (44.8% of IGPs and 48.5% of MCC‐GPs). Prescription improved by 12.3% after the intervention. There were marked deficiencies in the prescription of aldosterone antagonists (35%) for severe heart failure, which improved to 44.2% after the intervention.

Conclusion

The problem of inadequate implementation of evidence‐based therapy for CHF was partially overcome by using the reminder system, which provided participating physicians with short guideline recommendations during the intervention phase.