Basic and advanced numerical performances relate to mathematical expertise but are fully mediated by visuospatial skills

Recent studies have highlighted the potential role of basic numerical processing in the acquisition of numerical and mathematical competences. However, it is debated whether high-level numerical skills and mathematics depends specifically on basic numerical representations. In this study mathematicians and nonmathematicians performed a basic number line task, which required mapping positive and negative numbers on a physical horizontal line, and has been shown to correlate with more advanced numerical abilities and mathematical achievement. We found that mathematicians were more accurate compared with nonmathematicians when mapping positive, but not negative numbers, which are considered numerical primitives and cultural artifacts, respectively. Moreover, performance on positive number mapping could predict whether one is a mathematician or not, and was mediated by more advanced mathematical skills. This finding might suggest a link between basic and advanced mathematical skills. However, when we included visuospatial skills, as measured by block design subtest, the mediation analysis revealed that the relation between the performance in the number line task and the group membership was explained by non-numerical visuospatial skills. These results demonstrate that relation between basic, even specific, numerical skills and advanced mathematical achievement can be artifactual and explained by visuospatial processing

The measurement of Navier slip on individual nanoparticles in liquid

The Navier slip condition describes the motion of a liquid, relative to a neighboring solid surface, with its characteristic Navier slip length being a constitutive property of the solid-liquid interface. Measurement of this slip length is complicated by its small magnitude, expected in the nanometer range based on molecular simulations. Here, we report an experimental technique that interrogates the Navier slip length on individual nanoparticles immersed in liquid, with sub-nanometer precision. Proof-of-principle experiments on individual, citrate-stabilized, gold nanoparticles in water give a constant slip length of 2.7$\pm$0.6 nm (95% C.I.) - independent of particle size. Achieving this feature of size independence is central to any measurement of this constitutive property, which is facilitated through the use of individual particles of varying radii. This demonstration motivates studies that can now validate the wealth of existing molecular simulation data on slip.Comment: 12 pages, 4 figure

Lippen-Kiefer-Gaumen-Spalten: Individuelle Analyse der Lippenspalte durch 3-D-Lasertopometrie

Zusammenfassung: Hintergrund: Mit Gipsmodellen und Fotografien ist die dreidimensionale Analyse einer Lippen-Kiefer-Gaumen-Spalte meist nur unzureichend möglich. Ziel der vorliegenden Studie war es daher, die 3-D-Lasertopometrie auf ihre Anwendbarkeit zur dreidimensionalen Weichgewebserfassung bei Patienten mit Lippen-Kiefer-Gaumen-Spalten zu testen. Patienten und Methode: Bei 20 Patienten (3-35 Jahre), die eine einseitige, nicht operierte Lippen-, Lippen-Kiefer- oder Lippen-Kiefer-Gaumen-Spalte aufwiesen, wurde mit einem 3-D-Laserscanner die Gesichtsoberfläche prä- und postoperativ dreidimensional erfasst. Die dabei erzeugten digitalen Datensätze wurden in einer virtuellen Umgebung metrisch analysiert und anhand von Quotienten größenunabhängig wiedergegeben. Sie dienten der Auswahl der Operationstechnik und der Beurteilung des Operationsergebnisses. Ergebnisse: Mit dem 3-D-Laserscanner wurden 3-D-Oberflächen guter Qualität erstellt, die sich im Millimeterbereich ausmessen ließen. Die dreidimensionale Spaltmorphologie konnte in den Datensätzen reproduzierbar mit Landmarks versehen und vermessen werden. Auch die postoperative Symmetrie ließ sich so kontrollieren und objektivieren. Als nachteilig erwiesen sich die relativ lange Messzeit und die Notwendigkeit zur Kombination mehrerer Ansichten. Schlussfolgerung: Das vorgestellte 3-D-Laserverfahren ermöglicht eine präzise dreidimensionale Weichteilanalyse der Lippen- und Nasenregion bei Spaltpatienten. Es eignet sich jedoch nur bedingt für lebhafte Säuglinge und unkooperative Patiente

Inertial and viscous flywheel sensing of nanoparticles

Rotational dynamics often challenge physical intuition while enabling unique realizations, from the rotor of a gyroscope that maintains its orientation regardless of the outer gimbals, to a tennis racket that rotates around its handle when tossed face-up in the air. In the context of inertial mass sensing, which can measure mass with atomic precision, rotational dynamics are normally considered a complication hindering measurement interpretation. Here, we exploit the rotational dynamics of a microfluidic device to develop a new modality in inertial resonant sensing. Combining theory with experiments, we show that this modality normally measures the volume of the particle while being insensitive to its density. Paradoxically, particle density only emerges when fluid viscosity becomes dominant over inertia. We explain this paradox via a viscosity-driven, hydrodynamic coupling between the fluid and the particle that activates the rotational inertia of the particle, converting it into a viscous flywheel. This modality now enables the simultaneous measurement of particle volume and mass in fluid, using a single, high-throughput measurement.Comment: 20 pages, 4 figures, 12 s. figures, 2 s. table

Pauli's Principle in Probe Microscopy

Exceptionally clear images of intramolecular structure can be attained in dynamic force microscopy through the combination of a passivated tip apex and operation in what has become known as the "Pauli exclusion regime" of the tip-sample interaction. We discuss, from an experimentalist's perspective, a number of aspects of the exclusion principle which underpin this ability to achieve submolecular resolution. Our particular focus is on the origins, history, and interpretation of Pauli's principle in the context of interatomic and intermolecular interactions.Comment: This is a chapter from "Imaging and Manipulation of Adsorbates using Dynamic Force Microscopy", a book which is part of the "Advances in Atom and Single Molecule Machines" series published by Springer [http://www.springer.com/series/10425]. To be published late 201

Enterococcus faecalis resistant to vancomycin and teicoplanin (VanA phenotype) isolated from a bone marrow transplanted patient in Brazil

We report for the first time in Brazil, a patient from whom an Enterococcus faecalis VanA phenotype was isolated. Glycopeptide resistance is not commonly observed in Enterococcus faecalis, so this finding is of great concern since this species is responsible for 90% of enterococcal infections in Brazil. The isolate was recovered from a surveillance rectal swab culture from a patient with acute lymphocytic leukemia (ALL). Identification to the species level was performed by conventional biochemical tests and Vitek GPI cards. Antimicrobial susceptibility testing was evaluated by use of broth microdilution and Etest (AB BIODISK, Solna, Sweden) methods. The isolate was identified as E. faecalis and was considered resistant to both vancomycin (MIC, > 256 mug/mL) and teicoplanin (MIC, 256 mug/mL). The isolate also showed high level resistance to gentamicin and streptomycin (MICs, > 1024 mug/mL), but was considered susceptible to ampicillin (MIC, 4 mug/mL). Although the frequency of enterococcal infections is very low in most Latin America countries, the finding of glycopeptide (VanA) resistance in E. faecalis increases concern about apreading antimicrobial resistance in this region.Federal University of São Paulo Infectious Disease Division Special Clinical Microbiology LaboratoryFederal University of São Paulo Infectious Disease Division Nosocomial Infection Control CommitteeUniversity of Iowa College of Medicine Department of PathologySão Paulo Hospital Central LaboratoryUNIFESP, Infectious Disease Division Special Clinical Microbiology LaboratoryUNIFESP, Infectious Disease Division Nosocomial Infection Control CommitteeSciEL

Anisotrope Materialmodellierung für den menschlichen Unterkiefer

Im Rahmen der biomechanischen Simulation knöcherner menschlicher Organe ist die Frage nach einer befriedigenden Materialbeschreibung nach wie vor ungelöst. Computertomographische Datensätze liefern eine räumliche Verteilung der (Röntgen-) Dichte und ermöglichen damit eine gute Darstellung der individuellen Geometrie. Weiter können die verschiedenen Materialbestandteile des Knochens, Spongiosa und Kortikalis, voneinander getrennt werden. Aber die richtungsabhängige Information der Materialanisotropie ist verloren. In dieser Arbeit wird ein Ansatz für eine anisotrope Materialbeschreibung vorgestellt, die es ermöglicht, den Einfluss der individuellen knöchernen Struktur auf das makroskopische Materialverhalten abzuschätzen

Efficient and reliable finite element methods for simulation of the human mandible

By computed tomography data (CT), the individual geometry of the mandible is quite well reproduced, also the seperation of cortical and trabecular bone. Using anatomical knowledge about the architecture and the functional potential of the masticatory muscles realistic situations can be approximated. The solution of the underlying partial differential equations describing linear elastic material behaviour is provided by an adaptive finite element method. Estimates of the discretization errors, local grid refinement, and multilevel technique guarantee the reliability and efficiency of the method

Interaction imaging with amplitude-dependence force spectroscopy

Knowledge of surface forces is the key to understanding a large number of processes in fields ranging from physics to material science and biology. The most common method to study surfaces is dynamic atomic force microscopy (AFM). Dynamic AFM has been enormously successful in imaging surface topography, even to atomic resolution, but the force between the AFM tip and the surface remains unknown during imaging. Here, we present a new approach that combines high accuracy force measurements and high resolution scanning. The method, called amplitude-dependence force spectroscopy (ADFS) is based on the amplitude-dependence of the cantilever's response near resonance and allows for separate determination of both conservative and dissipative tip-surface interactions. We use ADFS to quantitatively study and map the nano-mechanical interaction between the AFM tip and heterogeneous polymer surfaces. ADFS is compatible with commercial atomic force microscopes and we anticipate its wide-spread use in taking AFM toward quantitative microscopy