1,926 research outputs found
Augmented Mitotic Cell Count using Field Of Interest Proposal
Histopathological prognostication of neoplasia including most tumor grading
systems are based upon a number of criteria. Probably the most important is the
number of mitotic figures which are most commonly determined as the mitotic
count (MC), i.e. number of mitotic figures within 10 consecutive high power
fields. Often the area with the highest mitotic activity is to be selected for
the MC. However, since mitotic activity is not known in advance, an arbitrary
choice of this region is considered one important cause for high variability in
the prognostication and grading.
In this work, we present an algorithmic approach that first calculates a
mitotic cell map based upon a deep convolutional network. This map is in a
second step used to construct a mitotic activity estimate. Lastly, we select
the image segment representing the size of ten high power fields with the
overall highest mitotic activity as a region proposal for an expert MC
determination. We evaluate the approach using a dataset of 32 completely
annotated whole slide images, where 22 were used for training of the network
and 10 for test. We find a correlation of r=0.936 in mitotic count estimate.Comment: 6 pages, submitted to BVM 2019 (bvm-workshop.org
Thermal annealing study of swift heavy-ion irradiated zirconia
Sintered samples of monoclinic zirconia (alpha-ZrO2) have been irradiated at
room temperature with 6.0-GeV Pb ions in the electronic slowing down regime.
X-ray diffraction (XRD) and micro-Raman spectroscopy measurements showed
unambiguously that a transition to the 'metastable' tetragonal phase
(beta-ZrO2) occurred at a fluence of 6.5x10^12 cm-2 for a large electronic
stopping power value (approx 32.5 MeV m-1). At a lower fluence of
1.0x10^12 cm-2, no such phase transformation was detected. The
back-transformation from beta- to alpha-ZrO2 induced by isothermal or
isochronal thermal annealing was followed by XRD analysis. The
back-transformation started at an onset temperature around 500 K and was
completed by 973 K. Plots of the residual tetragonal phase fraction deduced
from XRD measurements versus annealing temperature or time are analyzed with
first- or second-order kinetic models. An activation energy close to 1 eV for
the back-transformation process is derived either from isothermal annealing
curves, using the so-called "cross-cut" method, or from the isochronal
annealing curve, using a second-order kinetic law. Correlation with the thermal
recovery of ion-induced paramagnetic centers monitored by EPR spectroscopy is
discussed. Effects of crystallite size evolution and oxygen migration upon
annealing are also addressed
A large-scale dataset for mitotic figure assessment on whole slide images of canine cutaneous mast cell tumor
We introduce a novel, large-scale dataset for microscopy cell annotations. The dataset includes 32 whole slide images (WSI) of canine cutaneous mast cell tumors, selected to include both low grade cases as well as high grade cases. The slides have been completely annotated for mitotic figures and we provide secondary annotations for neoplastic mast cells, inflammatory granulocytes, and mitotic figure look-alikes. Additionally to a blinded two-expert manual annotation with consensus, we provide an algorithm-aided dataset, where potentially missed mitotic figures were detected by a deep neural network and subsequently assessed by two human experts. We included 262,481 annotations in total, out of which 44,880 represent mitotic figures. For algorithmic validation, we used a customized RetinaNet approach, followed by a cell classification network. We find F1-Scores of 0.786 and 0.820 for the manually labelled and the algorithm-aided dataset, respectively. The dataset provides, for the first time, WSIs completely annotated for mitotic figures and thus enables assessment of mitosis detection algorithms on complete WSIs as well as region of interest detection algorithms
Differences between kinematic synergies and muscle synergies during two-digit grasping
International audienceThe large number of mechanical degrees of freedom of the hand is not fully exploited during actual movements such as grasping. Usually, angular movements in various joints tend to be coupled, and EMG activities in different hand muscles tend to be correlated. The occurrence of covariation in the former was termed kinematic synergies, in the latter muscle synergies. This study addresses two questions: (i) Whether kinematic and muscle synergies can simultaneously accommodate for kinematic and kinetic constraints. (ii) If so, whether there is an interrelation between kinematic and muscle synergies. We used a reach-grasp-and-pull paradigm and recorded the hand kinematics as well as eight surface EMGs. Subjects had to either perform a precision grip or side grip and had to modify their grip force in order to displace an object against a low or high load. The analysis was subdivided into three epochs: reach, grasp-and-pull, and static hold. Principal component analysis (PCA, temporal or static) was performed separately for all three epochs, in the kinematic and in the EMG domain. PCA revealed that (i) Kinematic-and muscle-synergies can simultaneously accommodate kinematic (grip type) and kinetic task constraints (load condition). (ii) Upcoming grip and load conditions of the grasp are represented in kinematic-and muscle-synergies already during reach. Phase plane plots of the principal muscle-synergy against the principal kinematic synergy revealed (iii) that the muscle-synergy is linked (correlated, and in phase advance) to the kinematic synergy during reach and during grasp-and-pull. Furthermore (iv), pair-wise correlations of EMGs during hold suggest that muscle-synergies are (in part) implemented by coactivation of muscles through common input. Together, these results suggest that kinematic synergies have (at least in part) their origin not just in muscular activation, but in synergistic muscle activation. In short: kinematic synergies may result from muscle synergies
A completely annotated whole slide image dataset of canine breast cancer to aid human breast cancer research
Canine mammary carcinoma (CMC) has been used as a model to investigate the
pathogenesis of human breast cancer and the same grading scheme is commonly
used to assess tumor malignancy in both. One key component of this grading
scheme is the density of mitotic figures (MF). Current publicly available
datasets on human breast cancer only provide annotations for small subsets of
whole slide images (WSIs). We present a novel dataset of 21 WSIs of CMC
completely annotated for MF. For this, a pathologist screened all WSIs for
potential MF and structures with a similar appearance. A second expert blindly
assigned labels, and for non-matching labels, a third expert assigned the final
labels. Additionally, we used machine learning to identify previously
undetected MF. Finally, we performed representation learning and
two-dimensional projection to further increase the consistency of the
annotations. Our dataset consists of 13,907 MF and 36,379 hard negatives. We
achieved a mean F1-score of 0.791 on the test set and of up to 0.696 on a human
breast cancer dataset.Comment: 12 pages, 5 figure
Learning New Tricks from Old Dogs -- Inter-Species, Inter-Tissue Domain Adaptation for Mitotic Figure Assessment
For histopathological tumor assessment, the count of mitotic figures per area
is an important part of prognostication. Algorithmic approaches - such as for
mitotic figure identification - have significantly improved in recent times,
potentially allowing for computer-augmented or fully automatic screening
systems in the future. This trend is further supported by whole slide scanning
microscopes becoming available in many pathology labs and could soon become a
standard imaging tool.
For an application in broader fields of such algorithms, the availability of
mitotic figure data sets of sufficient size for the respective tissue type and
species is an important precondition, that is, however, rarely met. While
algorithmic performance climbed steadily for e.g. human mammary carcinoma,
thanks to several challenges held in the field, for most tumor types, data sets
are not available.
In this work, we assess domain transfer of mitotic figure recognition using
domain adversarial training on four data sets, two from dogs and two from
humans. We were able to show that domain adversarial training considerably
improves accuracy when applying mitotic figure classification learned from the
canine on the human data sets (up to +12.8% in accuracy) and is thus a helpful
method to transfer knowledge from existing data sets to new tissue types and
species.Comment: 5 pages, submission to BVM 202
Possible surface plasmon polariton excitation under femtosecond laser irradiation of silicon
The mechanisms of ripple formation on silicon surface by femtosecond laser
pulses are investigated. We demonstrate the transient evolution of the density
of the excited free-carriers. As a result, the experimental conditions required
for the excitation of surface plasmon polaritons are revealed. The periods of
the resulting structures are then investigated as a function of laser
parameters, such as the angle of incidence, laser fluence, and polarization.
The obtained dependencies provide a way of better control over the properties
of the periodic structures induced by femtosecond laser on the surface of a
semiconductor material.Comment: 11 pages, 8 figures, accepted for publication in Journal of Applied
Physic
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