600 research outputs found
Grabbing subitizing with both hands: bimanual number processing
No full textPlaisier M, Bergmann Tiest WM, Kappers AML. Grabbing subitizing with both hands: bimanual number processing. Experimental Brain Research. 2010;202(2):507-512
Cold objects pop out!
No full textPlaisier M, Kappers AML. Cold objects pop out!. In: Kappers AML, vanErp WM and van derHJBF and BT, eds. Haptics: Generating and perceiving tangible sensations. Vol 6192 of Lecture Notes on Computer Science. Berlin, Heidelberg: Berlin/Heidelberg: Springer; 2010: 219-224
The effect of feature saliency on haptic subitizing
No full textPlaisier M, Van 't Woud M, Kappers AML. The effect of feature saliency on haptic subitizing. Experimental Brain Research. 2011;209(1):29-34
Comparison of parameter sets for temporal decomposition
No full textTemporal decomposition of a speech utterance results in a description of speech parameters in terms of overlapping target functions and associated target factors. The former may correspond to articulatory gestures and the latter to ideal articulatory positions. Although developed for economical speech coding, this method also provides an interesting tool for deriving phonetic information from acoustic speech signals.
The speech parameters used by Atal (1983) is proposing this method were the log-area parameters. Our modified temporal decomposition method (Van Dijk-Kappers and Marcus, 1987, 1989) also works with log-area parameters as input. However, the method is not restricted to these; in principle, most commonly used parameter sets can be used. In this paper we compare the results obtained with nine different sets of speech parametes, including log-area parameters, formants, reflection coefficients and band-filter parameters.
The main criterion for good performance will be correspondence between target functions and phonemes or sub-phonemes. The phonetic relevance of the target vectors will also be considered, but in less detail. Speech signal resynthesis supplies yet another criterion; for those parameters sets which are transformable into the same parameter space, a reconstruction error will be defined and evaluated.
From these experiments it can be concluded that log-area parameters from the most suitable parameter set available for temporal decomposition. In some respects band-filter parameters yield better results, but this set is not classified as the best due to properties related to resynthesi
Haptic object individuation
No full textPlaisier M, Bergmann Tiest WM, Kappers AML. Haptic object individuation. IEEE Transactions on Haptics. 2010;3(4):257-265
The clinical and biological consequences of different FLT3 mutations in patients with AML
No full textCharacterisation of pathogenic markers in acute myeloid leukaemia (AML) may benefit
patients through refinement of risk stratification, application of molecularly targeted
therapy and improved understanding of AML biology. Whilst the presence of an
internal tandem duplication (ITD) within the fms-like tyrosine kinase-3 (FLT3) gene is
known to predict adverse outcome in young adults with AML, the clinical significance
of activating mutations in the tyrosine kinase domain (TKD) of FLT3 is unclear.
Therefore, a highly sensitive and specific denaturing-HPLC technique was developed to
screen for FLT3/TKDs in 1339 young adult patients with AML. Mutations were
detected in 161 (12%) cases, with a high incidence in patients with inv(16) (24%;
P=.009), a group in which FLT3/ITDs are uncommon. Unlike FLT3/ITDs, FLT3/TKDs
were associated with a favourable long-term outcome with a 10-year overall survival
(OS) of 36% for FLT3 WT, 51% for FLT3/ITD-TKD+ and 24% for FLT3/ITD+TKDpatients
(P<.001). The relative FLT3/TKD mutant level was highly variable with the
favourable prognosis residing in those patients with greater than 25% mutant alleles
(10-year OS of 59%), possibly reflecting the stage at which the mutation is acquired.
The mechanism of FLT3 activation also influenced sensitivity to FLT3-inhibitor
induced cytotoxicity, with FLT3/ITD+ blast cells more sensitive than FLT3/TKD+ cells.
Following lentiviral transduction, FLT3/ITD-transduced 32Dcl3 and Ba/F3 cells
demonstrated more rapid proliferation than FLT3/TKD-transduced cells. In an NB4 cell
line model of ATRA-induced myeloid differentiation, the presence of a FLT3/ITD
inhibited differentiation unlike a FLT3/TKD mutation which increased differentiation.
Furthermore, FLT3/ITD-transduced CD34 positive haematopoietic stem cells showed
greater cytokine-free survival of colony forming cells than FLT3/TKD-transduced cells.
Signalling studies also revealed that a FLT3/ITD induced stronger STAT5 activation
than a FLT3/TKD mutation. This unexpected genotype-phenotype relationship is of
direct relevance to current clinical decision making in AML, and may also provide
insights into mechanisms of chemoresistance
Salient features in three-dimensional haptic shape perception
No full textPlaisier M, Bergmann Tiest WM, Kappers AML. Salient features in three-dimensional haptic shape perception. Attention, Perception & Psychophysics. 2009;71(2):421-430
Moving the Weber fraction: the perceptual precision for moment of inertia increases with exploration force
No full textHow does the magnitude of the exploration force influence the precision of haptic perceptual estimates? To address this question, we examined the perceptual precision for moment of inertia (i.e., an object’s ‘‘angular mass’’) under different force conditions, using the Weber fraction to quantify perceptual precision. Participants rotated a rod around a fixed axis and judged its moment of inertia in a two-alternative forced-choice task. We instructed different levels of exploration force, thereby manipulating the magnitude of both the exploration force and the angular acceleration. These are the two signals that are needed by the nervous system to estimate moment of inertia. Importantly, one can assume that the absolute noise on both signals increases with an increase in the signals’ magnitudes, while the relative noise (i.e., noise/signal) decreases with an increase in signal magnitude. We examined how the perceptual precision for moment of inertia was affected by this neural noise. In a first experiment we found that a low exploration force caused a higher Weber fraction (22%) than a high exploration force (13%), which suggested that the perceptual precision was constrained by the relative noise. This hypothesis was supported by the result of a second experiment, in which we found that the relationship between exploration force and Weber fraction had a similar shape as the theoretical relationship between signal magnitude and relative noise. The present study thus demonstrated that the amount of force used to explore an object can profoundly influence the precision by which its properties are perceived
One, two, three, many - Subitizing in active touch
No full textPlaisier M, Bergmann Tiest WM, Kappers AML. One, two, three, many - Subitizing in active touch. Acta Psychologica. 2009;131(2):163-170
Haptic pop-out in a hand sweep
No full textPlaisier M, Bergmann Tiest WM, Kappers AML. Haptic pop-out in a hand sweep. Acta Psychologica. 2008;128(2):368-377
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