607 research outputs found
COMPUTED TOMOGRAPHY BASED PREDICTION OF ANGIOGRAPHIC DEPLOYMENT ANGLES MAY REDUCE PROCEDURE TIME AND CONTRAST MEDIUM VOLUME FOR TRANSCATHETER AORTIC VALVE REPLACEMENT
Planas Calvet, LluísPrimer pla d'edifici unifamiliar, de dos habitatges
adossats.De planta baixa, planta pis i golfes,
i una torrassa adossada. Són de gran qualitat
els esgrafiats del número 8 i les elaborades
reixes de ferro forjat del número 10
Nanogaps by direct lithography for high-resolution imaging and electronic characterization of nanostructures
We report a method for fabricating nanogaps directly with electron beam
lithography (EBL). The primary resolution-limit of EBL, electron
back-scattering, is reduced dramatically by using a thin-film as a substrate.
We show that this resolution enhancement allows one to fabricate metal
electrodes with separation from arbitrarily large to under one nanometer.
Furthermore, because these nanogaps are on a thin film, they can be imaged with
high-resolution transmission electron microscopy (HRTEM). Using these nanogaps
we measured the charge transport through several coupled PbSe nanocrystals and
correlated the data with detailed structural information obtained by performing
HRTEM on the same device.Comment: 9 pages, 3 figure
A Friendly Introduction to "Knowledge in Pieces": Modeling Types of Knowledge and Their Roles in Learning
Electron beam nanosculpting of suspended graphene sheets
We demonstrate high-resolution modification of suspended multi-layer graphene
sheets by controlled exposure to the focused electron beam of a transmission
electron microscope. We show that this technique can be used to realize, on
timescales of a few seconds, a variety of features, including nanometer-scale
pores, slits, and gaps that are stable and do not evolve over time. Despite the
extreme thinness of the suspended graphene sheets, extensive removal of
material to produce the desired feature geometries is found to not introduce
long-range distortion of the suspended sheet structure
Development of intuitive rules: Evaluating the application of the dual-system framework to understanding children's intuitive reasoning
This is an author-created version of this article. The original source of publication is Psychon Bull Rev. 2006 Dec;13(6):935-53
The final publication is available at www.springerlink.com
Published version: http://dx.doi.org/10.3758/BF0321390
Transverse Electronic Transport through DNA Nucleotides with Functionalized Graphene Electrodes
Graphene nanogaps and nanopores show potential for the purpose of electrical
DNA sequencing, in particular because single-base resolution appears to be
readily achievable. Here, we evaluated from first principles the advantages of
a nanogap setup with functionalized graphene edges. To this end, we employed
density functional theory and the non-equilibrium Green's function method to
investigate the transverse conductance properties of the four nucleotides
occurring in DNA when located between the opposing functionalized graphene
electrodes. In particular, we determined the electrical tunneling current
variation as a function of the applied bias and the associated differential
conductance at a voltage which appears suitable to distinguish between the four
nucleotides. Intriguingly, we observe for one of the nucleotides a negative
differential resistance effect.Comment: 19 pages, 7 figure
Individual differences in puberty onset in girls: Bayesian estimation of heritabilities and genetic correlations
We report heritabilities for individual differences in female pubertal development at the age of 12. Tanner data on breast and pubic hair development in girls and data on menarche were obtained from a total of 184 pairs of monozygotic and dizygotic twins. Genetic correlations were estimated to determine to what extent the same genes are involved in different aspects of physical development in puberty. A Bayesian estimation approach was taken, using Markovchain Monte Carlo simulation to estimate model parameters. All three phenotypes were to a significant extent heritable and showed high genetic correlations, suggesting that a common set of genes is involved in the timing of puberty in general. However, gonadarche (menarche and breast development) and adrenarche (pubic hair) are affected by different environmental factors, which does not support the three phenotypes to be regarded as indicators of a unitary physiological factor. © 2006 Springer Science+Business Media, Inc
Intuitive and Informal Knowledge in Preschoolers’ Development of Probabilistic Thinking
Preschoolers develop a wide range of mathematical informal knowledge and intuitive thinking before they enter formal, goal-oriented education. In their everyday activities young children get engaged with situations that enhance them to develop skills, concepts, strategies, representations, attitudes, constructs and operations concerning a wide range of mathematical notions. Recently there is scientific interest in linking children’s informal and formal knowledge in order to provide them with opportunities to avoid biases aiming at formulating, perceiving, reflecting on and exercising probabilistic notions. The current study investigates preschoolers’ (N=90) intuitive understanding of the likelihood of events in a probabilistic task with spinners. Participants, at the age of 4 to 6, are tested on their predictions of the most probable outcome prior to and after an instructive session of reasoning. The
probabilistic task, based on constructivist principles, includes methodological alterations concerning the sample space and the themes of the stimuli. Educational implications are further discussed under the general point of view that in order to link informal to formal mathematical learning in preschool classroom, the subject
content and the cognitive capacity of children are important to match
Simultaneous genetic analysis of longitudinal means and covariance structure in the simplex model using twin data
A longitudinal model based on the simplex model is presented to analyze simultaneously means and covariance structure using univariate longitudinal twin data. The objective of the model is to decompose the mean trend into components which can be attributed to those genetic and environmental factors which give rise to phenotypic individual differences and a component of unknown constitution which does not involve individual differences. Illustrations are given using simulated data and repeatedly measured weight obtained in a sample of 82 female twin pairs on sbc occasions. KEY WORDS: repeated measures; genetic and environmental covariance structure; mean trend; longitudinal twin data; genetic simplex mode; LISREL
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