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Squaring the circle

Robert M O'Brien
Venn diagrams are used to provide an intuitive understanding of multiple regression analysis and these diagrams work well with two variables. The area of overlap of the two variables has a one-to-one relationship to the squared correlation between them. This approach breaks down, however, with three-variables. Making the overlap between the pairs of variables consistent with their squared bivariate correlations often results in the overlap of two of these variables with the third variable that is not the same as the variance of the third variable accounted for by the other two variables...
2018: PloS One
Manuela Galli, Veronica Cimolin, Giacomo Stella, Maria Francesca De Pandis, Andrea Ancillao, Claudia Condoluci
Drawing tests in children diagnosed with dyslexia and dysgraphia were quantitatively compared. Fourteen children with dysgraphia, 19 with dyslexia and 13 normally developing were asked to copy 3 figures: a circle, a square and a cross. An optoelectronic system allowed the acquisition of the drawing track in three-dimensions. The participants' head position and upper limb movements were measured as well. A set of parameters including movement duration, velocity, length of the trace, Range of Motion of the upper limb, was computed and compared among the 3 groups...
May 7, 2018: Human Movement Science
Nick Berggren, Martin Eimer
During visual search, attention is believed to be controlled in a strictly feature-based fashion, without any guidance by object-based target representations. To challenge this received view, we measured electrophysiological markers of attentional selection (N2pc component) and working memory (sustained posterior contralateral negativity; SPCN) in search tasks where two possible targets were defined by feature conjunctions (e.g., blue circles and green squares). Critically, some search displays also contained nontargets with two target features (incorrect conjunction objects, e...
May 3, 2018: Journal of Experimental Psychology. Human Perception and Performance
Olga V Vyazovska, Victor M Navarro, Edward A Wasserman
We trained 8 pigeons ( Columba livia ) on a stagewise go/no-go visual discrimination task of increasing complexity, to document the dynamics of selective attention. We constructed negative compound stimuli (S-s) on the basis of their overall similarity to a positive compound stimulus (S+) along 4 binary-valued dimensions: shape (circle/square), size (large/small), line orientation (horizontal/vertical), and brightness (dark/light). Starting with 1 S+ and 1 S- that differed in all 4 dimensional values, in 3 later steps, we progressively added S-s sharing 1, 2, and finally 3 dimensional values with the S+...
April 2018: Journal of Experimental Psychology. Animal Learning and Cognition
Mingzhi Luo, Xiang Chen, Shuai Cao, Xu Zhang
Time difference of arrival (TDoA) measurement is a promising approach for target localization based on a set of nodes with known positions, with high accuracy and low complexity. Common localization algorithms include the maximum-likelihood, non-linear least-squares and weighted least-squares methods. These methods have shortcomings such as high computational complexity, requiring an initial guess position, or having difficulty in finding the optimal solution. From the point of view of geometrical analysis, this study proposes two new shrinking-circle methods (SC-1 and SC-2) to solve the TDoA-based localization problem in a two-dimensional (2-D) space...
April 20, 2018: Sensors
Christine Mertes, Daniel Schneider
Using event-related potentials (ERPs) of the electroencephalogram, we investigated how cognitive control is altered by the scope of an attentional template currently activated in visual working memory. Participants performed a spatial cuing task where an irrelevant color singleton cue was presented prior to a target array. Blockwise, the target was either a red circle or a gray square and had to be searched within homogenous (gray circles) or heterogeneous non-targets (differently colored circles or various shapes)...
2018: Frontiers in Human Neuroscience
Rebecca Saive, Harry A Atwater
We report on a computational study exploring the design of mesoscale metallic front contacts for solar cells. We investigated silver contact structures with circle, triangle and square cross-sections for various length scales and surface coverages. We found that for 'nanoscale' contacts with widths between 10 nm and 1000 nm, resonant coupling actually impairs light absorption in the semiconductor. Conversely, for 'mesoscale' contact widths > 1000 nm, the light interaction is determined by the geometric shadowing...
March 19, 2018: Optics Express
Nicole Fider, Natalia L Komarova
We use World Color Survey (WCS) data to design quantitative methods to study color categorization, with the focus on the "geometric" properties of categories, in particular, on studying their shape, and creating a consistent methodology to identify category boundaries. We introduce the notion of "No Man's Land" and "Some Man's Land" to distinguish color chips that belong to no color category and those that belong to some color category. We introduce a "color-stimulus-strength" function that characterizes color boundaries...
April 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Anton Khlopas, Morad Chughtai, Randa K Elmallah, David Hip-Flores, Arthur L Malkani, Steven F Harwin, Michael A Mont, Michael D Ries
BACKGROUND: Bone loss in patients undergoing revision THA poses a considerable challenge for orthopaedic surgeons. Often, to achieve better fixation in remaining bone, larger diameter acetabular components and reaming superiorly may be necessary. However, this is likely to raise the hip center of rotation, which may lead to altered biomechanics, specifically, insufficiency of the abductor muscles, altered gait, and increased risk of dislocation from impingement. More recently, a newer acetabular shell has been designed to more closely replicate the native hip center of rotation in these circumstances while maintaining adequate fixation...
February 2018: Clinical Orthopaedics and related Research
Yu Bin Lee, Eun Mi Kim, Hayeon Byun, Hyung-Kwan Chang, Kwanghee Jeong, Zachary M Aman, Yu Suk Choi, Jungyul Park, Heungsoo Shin
Numerous methods have been reported for the fabrication of 3D multi-cellular spheroids and their use in stem cell culture. Current methods typically relying on the self-assembly of trypsinized, suspended stem cells, however, show limitations with respect to cell viability, throughput, and accurate recapitulation of the natural microenvironment. In this study, we developed a new system for engineering cell spheroids by self-assembly of micro-scale monolayer of stem cells. We prepared synthetic hydrogels with the surface of chemically formed micropatterns (squares/circles with width/diameter of 200 μm) on which mesenchymal stem cells isolated from human nasal turbinate tissue (hTMSCs) were selectively attached and formed a monolayer...
May 2018: Biomaterials
Dejan Todorović, Ljubica Jovanović
The Ebbinghaus illusion, in which a central target surrounded by larger context figures looks smaller than when surrounded by smaller context figures, is usually classified as a size contrast illusion. Thus "size contrast" is the dominant account of this effect. However, according to an alternative "contour interaction" account this phenomenon has little to do with size contrast but is rather caused by distance-dependent attractive and repulsive interactions between neural representation of contours...
April 2018: Acta Psychologica
Jing-Min Liu, Xiao-Long Zhang, Yu Zhai, Hui Li
The calculated rovibrational energy levels and infrared spectra for OCS-( pH2 )2 , OCS-( oD2 )2 , OCS-(HD)2 and mixed OCS- pH2 -He trimers are obtained by performing the exact basis-set calculations for the first time based on the newly developed potential energy surfaces ( J. Chem. Phys. 2017, 147, 044313). The "adiabatic-hindered-rotor" (AHR) method is used for reduced-dimension treatment of the hydrogen rotation. The predicted band origin shifts and the infrared spectra are in good agreement with the available experimental values: for the band origin shifts and infrared transitions, the root-mean-square(rms) deviations are smaller than 0...
March 22, 2018: Journal of Physical Chemistry. A
Cassandra Philine Köller, Christian H Poth, Arvid Herwig
Object perception across saccadic eye movements is assumed to result from integrating two information sources: incoming peripheral object information and information from a foveal prediction (Herwig and Schneider, J Exp Psychol Gen 143(5):1903-1922, 2014, Herwig, J Vis 15(16), 7, 2015). Predictions are supposed to be based on transsaccadic associations of peripheral and foveal object information. The main function of these predictions may be to conceal discrepancies in resolution and locations across saccades...
January 31, 2018: Psychological Research
Armen Poghosyan, Nickolay Izmailian, Ralph Kenna
The Ising model in two dimensions with special toroidal boundary conditions is analyzed. These boundary conditions, which we call duality-twisted boundary conditions, may be interpreted as inserting a specific defect line ("seam") in the system, along noncontractible circles of the cylinder, before closing it into a torus. We derive exact expressions for the eigenvalues of a transfer matrix for the critical ferromagnetic Ising model on the M×N square lattice wrapped on the torus with a specific defect line...
December 2017: Physical Review. E
Vani Virdyawan, Matthew Oldfield, Ferdinando Rodriguez Y Baena
Puncturing blood vessels during percutaneous intervention in minimally invasive brain surgery can be a life threatening complication. Embedding a forward looking sensor in a rigid needle has been proposed to tackle this problem but, when using a rigid needle, the procedure needs to be interrupted and the needle extracted if a vessel is detected. As an alternative, we propose a novel optical method to detect a vessel in front of a steerable needle. The needle itself is based on a biomimetic, multi-segment design featuring four hollow working channels...
January 11, 2018: Bioinspiration & Biomimetics
Adeola N Harewood Smith, Jnana Aditya Challa, Michael A Silver
Acetylcholine and dopamine are neurotransmitters that play multiple important roles in perception and cognition. Pharmacological cholinergic enhancement reduces excitatory receptive field size of neurons in marmoset primary visual cortex and sharpens the spatial tuning of visual perception and visual cortical fMRI responses in humans. Moreover, previous studies show that manipulation of cholinergic or dopaminergic signaling alters the spatial tuning of macaque prefrontal cortical neurons during the delay period of a spatial working memory (SWM) task and can improve SWM performance in macaque monkeys and human subjects...
2017: Frontiers in Neural Circuits
Sakari Kallio, Mika Koivisto, Johanna K Kaakinen
Are synaesthetic experiences congenital and so hard-wired, or can a functional analogue be created? We induced an equivalent of form-colour synaesthesia using hypnotic suggestions in which symbols in an array (circles, crosses, squares) were suggested always to have a certain colour. In a Stroop type-naming task, three of the four highly hypnotizable participants showed a strong synaesthesia-type association between symbol and colour. This was verified both by their subjective reports and objective eye-movement behaviour...
December 11, 2017: Scientific Reports
Alar Ainla, Mohit S Verma, Dian Yang, George M Whitesides
This article describes a soft pneumatic actuator that generates cyclical motion. The actuator consists of several (three, four, or five) chambers (arranged around the circumference of a circle surrounding a central rod) that can be actuated independently using negative pressure (or partial vacuum). Sequential actuation of the four-chamber device using reduced pressure moves the central rod cyclically in an approximately square path. We characterize the trajectory of the actuator and the force exerted by it, as we vary the material used for fabrication, the number of chambers, and the size of the actuator...
September 2017: Soft Robotics
P Godoy, M Alsedà, M Falguera, T Puig, P Bach, M Monrabà, A Manonelles
The transmission of tuberculosis (TB) in bars is difficult to study. The objective was to describe a large TB outbreak in a company's bar and other leisure settings. A descriptive study of a TB outbreak was carried out. Contacts were studied in the index case's workplace bar (five circles of contacts) and other recreational areas (social network of three bars in the index case's neighbourhood). Chest X-rays were recommended to contacts with positive tuberculin skin tests (TST) (⩾5 mm). The risk of latent tuberculosis infection (LTBI) was determined using an adjusted odds ratio...
December 2017: Epidemiology and Infection
David M Williams, Toby Nicholson, Catherine Grainger
Memory for (and perception of) information about the self is superior to memory for (and perception of) other kinds of information. This self-reference effect (SRE) in memory appears diminished in ASD and related to the number of ASD traits manifested by neurotypical individuals (fewer traits = larger SRE). Here, we report the first experiments exploring the relation between ASD and the SRE in perception. Using a "Shapes" Task (Sui et al., Journal of Experimental Psychology: Human Perception and Performance, 38, 1105, 2012), participants learned to associate three different shapes (triangle, circle, square) with three different labels representing self, a familiar other, or an unfamiliar other (e...
February 2018: Autism Research: Official Journal of the International Society for Autism Research
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