Operational thought and the acquisition of taxonomic relations involving figurative dissimilarity.

Atypical exemplars of taxonomic categories (e.g., clothing, furniture) differ from more typical exemplars along figurative dimensions of perceptual and contextual similarity. The advent of operational thought might be expected to facilitate category acquisition because it engenders a competence to suppress figurative dissimilarities and focus on nonfigurative similarities (e.g., common function). Age- and grade-equivalent preoperational and concrete operational groups were given oddity, sort, and category membership tasks with pictorial stimuli. Concrete operational subjects showed a greater appreciation than preoperational subjects for taxonomic relations involving atypical exemplars. Subjects of both cognitive levels could appreciate taxonomic relations involving strictly typical or moderately typical exemplars of a category. Results are interpreted as supporting a contention that meanings become more general with the emergence of operational thought. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dynamic and viscoelastic behavior of natural rubber/layered silicate nanocomposites obtained by melt blending

Vulcanized natural rubber/layered silicate (montmorillonite) nanocomposites prepared by melt blending with different contents of organoclay (0, 5, 10, 20 wt%) were investigated. The morphological characteristics of the materials were studied by transmission electron microscopy (TEM), wide angle X-ray diffraction, and dynamic mechanical thermal analysis (DMTA). X-ray spectra evidence some intercalation of the clay, while TEM results show a good dispersion of the clay and the occurrence of partial delamination. DMTA analysis with varying temperature shows that the peak of the loss modulus broadens by increasing the clay content within the material, though the peak temperature is scarcely affected. Mechanical reinforcement induced by the presence of the clay is evidenced by static tensile tests. At every clay content explored, dynamic experiments show a nonlinear behavior (Payne effect), which strongly increases with the amount of clay incorporated and is considerably more pronounced than in natural rubber filled with comparable amounts of conventional fillers. The viscoelastic behavior of the materials is investigated by recovery tests of low amplitude storage modulus, carried out after the application of a large strain perturbation, and by stress relaxation experiments. POLYM. ENG. SCI., 47:1650–1657, 2007. © 2007 Society of Plastics Engineers     

MOSFET's negative transconductance at room temperature

Negative transconductance is reported for the first time at T=300 K for NMOS transistors fabricated with different technologies and oxide thickness in the 3-20 nm range. The effects of drain bias, channel length, oxide thickness as well as substrate doping and bias on the phenomenon are investigated. The results are interpreted in terms of surface-roughness limited mobility, and parameters for mobility modeling at high effective fields are extracted     

Vascular Architecture Generates Fine Scale Variation in Systemic Induction of Proteinase Inhibitors in Tomato

Systemic induction following damage has been found in many plant species. Despite this widespread appreciation for the importance of induction, few studies have characterized the spatial variability of induction. We used tomato, Lycopersicon esculentum, to examine how damage to a single leaf affected the spatial distribution of systemic induction of proteinase inhibition in leaves above the damaged leaf. We crushed each leaflet of the second true leaf with forceps and measured the spatial distribution of proteinase inhibition in leaves 3, 4, and 5 at 8, 16, 24, 48, 72, and 120 hr. Constitutive levels of proteinase inhibitor activity were quantified in undamaged plants. We hypothesized that, due to vascular control of signal movement, systemic induction would show both among and within leaf variability. Following damage to leaf 2, induction was most pronounced in leaf 5 and minimal in leaf 3. In general, proteinase inhibitor activity was greatest at 24 hr and then declined. As predicted by vascular architecture, the near side of leaves in adjacent orthostichies showed higher induction than the far side of leaves. There was no increase in proteinase inhibitor activity in the undamaged neighboring plants. Overall our results demonstrate that systemic induction of proteinase inhibitors is partially controlled by vascular architecture and that future studies on systemic induction should examine the vascular architecture of the plants being studied. We argue that this spatial variation may influence the performance of herbivores sensitive to induced chemical changes.     

Copper(I/II), α/β‐Synuclein and Amyloid‐β: Menage à Trois?

Copper binding to α‐synuclein (aS) and to amyloid‐β (Ab) has been connected to Parkinson's and Alzheimer's disease (AD), respectively, because Cu ions can modulate the peptide aggregation, and these Cu ? peptide complexes can catalyse the production of reactive oxygen species (ROS). In a significant proportion of AD brains, aggregation of aS and Ab has been detected, and it was proposed that Ab and aS interact with each other. Thus, we investigated the potential interactions of Ab and aS through their binding of copper(I) and copper(II). Additionally, β‐synuclein (bS) was investigated, due to its additional methionine residue, a potential Cu^I ligand. We found that: 1) the peptides containing the Cu‐binding domains Ab1–16, aS1–15 and bS1–15 have similar affinities towards Cu^II and towards Cu^I, with Ab1–16 being slightly stronger, 2) in the case of Cu^I, the additional Met residue in bS1–15 increased the affinity slightly, 3) the exchange of Cu^I/II between the two peptides is rapid (≤ms), 4) a/bS1–15 and Ab1–16 form a heterodimeric complex with Cu^II, 5) Cu^I probably promotes a transient ternary complex, 6) the different Cu^I/II coordination of Ab1–16, aS1–15 and bS1–15 impacts the capacity to produce ROS and to oxidise catechol, and 7) when Ab1–16, aS1–15 and Cu are present, the ROS production more closely resembles that by Ab1–16. The work gives insights into the coordination chemistry of these related peptides, and the relevance of coordination differences, the ternary complex and ROS production are discussed.     

Linux-Based Data Acquisition and Processing on Palmtop Computer

This paper presents an original implementation of a Personal Computer Memory Card International Association data acquisition card on a palmtop computer. The acquisition system is based on the Linux operating system and free drivers for the acquisition board. The system has been used to develop a demo application consisting in a phonometer able to sample 1024 samples at 100 ksamples/s and compute the fast Fourier transform of the signal at a maximum rate of 6 frame/s     

Map integration at human chromosome 10: molecular and cytogenetic analysis of a chromosome-specific somatic cell hybrid panel and genomic clones, based on a well-supported genetic map

Well-characterized, chromosome-specific somatic cell hybrid panels are powerful tools for the analysis of the human genome. We have characterized a panel of human x hamster somatic cell hybrids retaining fragments of human chromosome 10 by fluorescence in situ hybridization and associated them to genetic markers. Most of the hybrids were generated by the radiation-reduction method, starting from a chromosome 10-specific monochromosomal hybrid, whereas some were collected from hybrids retaining chromosome 10-specific fragments as a result of spontaneous in vitro rearrangements. PCR was used to score the retention of 57 microsatellite markers evenly distributed along a well-supported framework genetic map containing 149 loci uniquely placed at 69 anchor points (odds exceeding 1,000:1), with an average spacing of 2.8 cM. As an additional resource for genomic studies involving human chromosome 10, we report the cytogenetic localization of a series of YAC and PAC clones recognized by at least one genetic marker. Somatic cell hybrids provide a powerful source of partial chromosome paints useful for detailed clinical cytogenetic and primate chromosome evolution investigations. Furthermore, correlation of the above physical, genetic, and cytogenetic data contribute to an emerging consensus map of human chromosome 10.     

Nonscaling of MOSFET's linear resistance in the deep submicrometerregime

This paper investigates the scaling properties of deep submicron MOSFET's and shows that, while in a wide range of channel lengths they can be represented as composed by a scaling intrinsic and a nonscaling parasitic part, this picture does no longer hold for shorter transistors. A nonscaling of the total resistance R_TOT=[V_DS/I_DS] of short devices is observed, and its impact on parasitic resistances and effective channel length extraction is discussed. A possible explanation is suggested in relation to the two-dimensional substrate doping redistribution linked to reverse-short-channel effects     

Numerical analysis of the gate voltage dependence of the seriesresistances and effective channel length in submicrometer GaAs MESFETs

A detailed numerical analysis of the source and drain parasitic resistances and effective channel length of state-of-the-art GaAs MESFETs is presented. Two-dimensional simulations are used to evaluate different criteria (physical and electrical) for defining the device parameters of interest, as well as to study their gate voltage dependence. To this purpose a novel criterion which provides a simple procedure to determine the series resistances as a function of gate bias is proposed     

1-out-of-3 code checker with single output

A CMOS 1-out-of-3 code checker with single output is presented which, compared to available implementations, offers the general advantages of featuring a single output and requiring lower area overhead and dynamic power consumption