8,405 research outputs found
Ability to recall specific detail and general detail (gist) in young old, middle old, and older adults
Facial recognition and visual processing as we age:Using the Thatcher illusion with famous and non-famous faces
This paper reports a study examining preferred visual processes in recognition of facial features in older vs younger age groups, using Thatcherised images of famous and non-famous people in the one study. The aims were to determine whether decline in visual system processing occurs increasingly as we grow older, and whether there is less decline in recognition of famous (or familiar) faces. Three groups (younger, middle-old and older) made up the sample of 73 people (aged 19-82 years). Visual decline in face recognition across the age groups was assessed based on the Thatcher illusion—using four famous and four non-famous faces either with normal features or with distorted features. The faces were presented one at a time on computer screen, and participants were asked to judge whether the face was distorted (eyes and/or mouth not aligned in relation to the face); in addition, time taken to decision (latency) was also measured. Decline was found in visual processing such that older individuals gave limited attention to facial details (processing faces holistically, with detail errors) and they took longer to decide. Whether the faces were famous or not did not have significant effects on the decisions and there was no interaction with age, though famous faces were given longer attention. Our visual system processes decline as we age in that we give less attention to details and more to holistic processing and so make more errors in recognition. Implications for treatment or amelioration of the effects are discussed.</jats:p
Rhapso : automatic stitching of mass segments from fourier transform ion cyclotron resonance mass spectra
Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) provides the resolution and mass accuracy needed to analyze complex mixtures such as crude oil. When mixtures contain many different components, a competitive effect within the ICR cell takes place that hampers the detection of a potentially large fraction of the components. Recently, a new data collection technique, which consists of acquiring several spectra of small mass ranges and assembling a complete spectrum afterward, enabled the observation of a record number of peaks with greater accuracy compared to broadband methods. There is a need for statistical methods to combine and preprocess segmented acquisition data. A particular challenge of quadrupole isolation is that near the window edges there is a drop in intensity, hampering the stitching of consecutive windows. We developed an algorithm called Rhapso to stitch peak lists corresponding to multiple different m/z regions from crude oil samples. Rhapso corrects potential edge effects to enable the use of smaller windows and reduce the required overlap between windows, corrects mass shifts between windows, and generates a single peak list for the full spectrum. Relative to a stitching performed manually, Rhapso increased the data processing speed and avoided potential human errors, simplifying the subsequent chemical analysis of the sample. Relative to a broadband spectrum, the stitched output showed an over 2-fold increase in assigned peaks and reduced mass error by a factor of 2. Rhapso is expected to enable routine use of this spectral stitching method for ultracomplex samples, giving a more detailed characterization of existing samples and enabling the characterization of samples that were previously too complex to analyze
The Effects of Varying Cosmological Parameters on Halo Substructure
We investigate how different cosmological parameters, such as those delivered
by the WMAP and Planck missions, affect the nature and evolution of dark matter
halo substructure. We use a series of flat cold dark matter
(CDM) cosmological -body simulations of structure formation, each
with a different power spectrum but the same initial white noise field. Our
fiducial simulation is based on parameters from the WMAP 7th year cosmology. We
then systematically vary the spectral index, , matter density, ,
and normalization of the power spectrum, , for 7 unique simulations.
Across these, we study variations in the subhalo mass function, mass fraction,
maximum circular velocity function, spatial distribution, concentration,
formation times, accretion times, and peak mass. We eliminate dependence of
subhalo properties on host halo mass and average over many hosts to reduce
variance. While the "same" subhalos from identical initial overdensity peaks in
higher , and simulations accrete earlier and end up
less massive and closer to the halo center at , the process of continuous
subhalo accretion and destruction leads to a steady state distribution of these
properties across all subhalos in a given host. This steady state mechanism
eliminates cosmological dependence on all properties listed above except
subhalo concentration and , which remain greater for higher and simulations, and subhalo formation time, which remains
earlier. We also find that the numerical technique for computing scale radius
and the halo finder used can significantly affect the concentration-mass
relationship computed for a simulation.Comment: 15 pages, 15 figures, Accepted to ApJ on March 15, 201
A minimal model for spontaneous cell polarization and edge activity in oscillating, rotating and migrating cells
How the cells break symmetry and organize their edge activity to move
directionally is a fun- damental question in cell biology. Physical models of
cell motility commonly rely on gradients of regulatory factors and/or feedback
from the motion itself to describe polarization of edge activity. Theses
approaches, however, fail to explain cell behavior prior to the onset of
polarization. Our analysis using the model system of polarizing and moving fish
epidermal keratocytes suggests a novel and simple principle of
self-organization of cell activity in which local cell-edge dynamics depends on
the distance from the cell center, but not on the orientation with respect to
the front-back axis. We validate this principle with a stochastic model that
faithfully reproduces a range of cell-migration behaviors. Our findings
indicate that spontaneous polarization, persistent motion, and cell shape are
emergent properties of the local cell-edge dynamics controlled by the distance
from the cell center.Comment: 8 pages, 5 figure
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