2,318 research outputs found
An Adaptive Sampling Scheme to Efficiently Train Fully Convolutional Networks for Semantic Segmentation
Deep convolutional neural networks (CNNs) have shown excellent performance in
object recognition tasks and dense classification problems such as semantic
segmentation. However, training deep neural networks on large and sparse
datasets is still challenging and can require large amounts of computation and
memory. In this work, we address the task of performing semantic segmentation
on large data sets, such as three-dimensional medical images. We propose an
adaptive sampling scheme that uses a-posterior error maps, generated throughout
training, to focus sampling on difficult regions, resulting in improved
learning. Our contribution is threefold: 1) We give a detailed description of
the proposed sampling algorithm to speed up and improve learning performance on
large images. We propose a deep dual path CNN that captures information at fine
and coarse scales, resulting in a network with a large field of view and high
resolution outputs. We show that our method is able to attain new
state-of-the-art results on the VISCERAL Anatomy benchmark
Volumetric Attention for 3D Medical Image Segmentation and Detection
A volumetric attention(VA) module for 3D medical image segmentation and
detection is proposed. VA attention is inspired by recent advances in video
processing, enables 2.5D networks to leverage context information along the z
direction, and allows the use of pretrained 2D detection models when training
data is limited, as is often the case for medical applications. Its integration
in the Mask R-CNN is shown to enable state-of-the-art performance on the Liver
Tumor Segmentation (LiTS) Challenge, outperforming the previous challenge
winner by 3.9 points and achieving top performance on the LiTS leader board at
the time of paper submission. Detection experiments on the DeepLesion dataset
also show that the addition of VA to existing object detectors enables a 69.1
sensitivity at 0.5 false positive per image, outperforming the best published
results by 6.6 points.Comment: Accepted by MICCAI 201
Electron Conditioning of Technical Aluminium Surfaces: Effect on the Secondary Electron Yield
The effect of electron conditioning on commercially aluminium alloys 1100 and
6063 were investigated. Contrary to the assumption that electron conditioning,
if performed long enough, can reduce and stabilize the SEY to low values (, value of many pure elements), the SEY of aluminium did not go lower than
1.8. In fact, it reincreases with continued electron exposure dose.Comment: 36 pages, 25 figures, submitted to JVST
Dimensional regularization of nonlinear sigma models on a finite time interval
We extend dimensional regularization to the case of compact spaces. Contrary
to previous regularization schemes employed for nonlinear sigma models on a
finite time interval (``quantum mechanical path integrals in curved space'')
dimensional regularization requires only a covariant finite two-loop
counterterm. This counterterm is nonvanishing and given by R/8.Comment: 9 pages, 7 figures, LaTeX, minor changes in text and reference
Changing the ideological roots of prejudice: Longitudinal effects of ethnic intergroup contact on social dominance orientation
Social Dominance Orientation (SDO) has been reported to be strongly related to a multitude of intergroup phenomena, but little is known about situational experiences that may influence SDO. Drawing from research on intergroup contact theory, we argue that positive intergroup contact is able to reduce SDO-levels. The results of an intergroup contact intervention study among high school students (Study 1, N=71) demonstrated that SDO-levels were indeed attenuated after the intervention. Furthermore, this intervention effect on SDO was especially pronounced among students reporting a higher quality of contact. A cross-lagged longitudinal survey among adults (Study 2, N=363) extended these findings by demonstrating that positive intergroup contact is able to decrease SDO over time. Moreover, we did not obtain evidence for the idea that people high in SDO would engage less in intergroup contact. These findings indicate that intergroup contact erodes one of the important socio-ideological bases of generalized prejudice and discrimination
Study of the finite temperature transition in 3-flavor QCD using the R and RHMC algorithms
We study the finite temperature transition in QCD with three flavors of equal
masses using the R and RHMC algorithm on lattices with temporal extent
N_{\tau}=4 and 6. For the transition temperature in the continuum limit we find
r_0 T_c=0.429(8) for the light pseudo-scalar mass corresponding to the end
point of the 1st order transition region. When comparing the results obtained
with the R and RHMC algorithms for p4fat3 action we see no significant
step-size errors down to a lightest pseudo-scalar mass of m_{ps} r_0=0.4.Comment: 13 pages, RevTeX, 10 figure
B-meson decay constants from 2+1-flavor lattice QCD with domain-wall light quarks and relativistic heavy quarks
We calculate the B-meson decay constants fB, fBs, and their ratio in unquenched lattice QCD using domain-wall light quarks and relativistic b quarks. We use gauge-field ensembles generated by the RBC and UKQCD collaborations using the domain-wall fermion action and Iwasaki gauge action with three flavors of light dynamical quarks. We analyze data at two lattice spacings of a ~ 0.11, 0.086 fm with unitary pion masses as light as MÏ ~ 290 MeV; this enables us to control the extrapolation to the physical light-quark masses and continuum. For the b quarks we use the anisotropic clover action with the relativistic heavy-quark interpretation, such that discretization errors from the heavy-quark action are of the same size as from the light-quark sector. We renormalize the lattice heavy-light axial-vector current using a mostly nonperturbative method in which we compute the bulk of the matching factor nonperturbatively, with a small correction, that is close to unity, in lattice perturbation theory. We also improve the lattice heavy-light current through O (αsa). We extrapolate our results to the physical light-quark masses and continuum using SU(2) heavy-meson chiral perturbation theory, and provide a complete systematic error budget. We obtain fB0 = 199.5(12.6) MeV, fB+ = 195.6(14.9) MeV, fBs = 235.4(12.2) MeV, fBs/fB0 = 1.197(50), and fBs/fB+ = 1.223(71), where the errors are statistical and total systematic added in quadrature. These results are in good agreement with other published results and provide an important independent cross-check of other three-flavor determinations of B-meson decay constants using staggered light quarks
How do we get people into contact? Predictors of intergroup contact and drivers of contact seeking
Compared to the impressive amount of research on consequences of intergroup contact, relatively little work has been devoted to predictors of intergroup contact. Although opportunities for intergroup contact are constantly growing in modern diverse societies, these contact opportunities are not necessarily exploited. In the present review article, we describe current research on predictors of intergroup contact and drivers of contact seeking on a microâ, mesoâ, and macroâlevel. We provide an overview of predictors, while focusing on recent research that is especially relevant for designing interventions and planning social policies aiming at increasing contact between different groups in varied societies. On the microâlevel, we discuss relational selfâexpansion motives and confidence in contact as predictors of intergroup contact. On the mesoâlevel, we focus on the role of intragroup processes and historical intergroup conflicts in facilitating contact. On the macroâlevel, we reflect on changing societal norms as a potential tool to increase the frequency intergroup contact. By focusing on the applied value of research findings, discussing diverse predictors, and applying a multilevel approach, we also address recent criticisms of the intergroup contact literature and demonstrate the generative nature of contemporary research in this area
The transition temperature in QCD
We present a detailed calculation of the transition temperature in QCD with
two light and one heavier (strange) quark mass on lattices with temporal extent
N_t =4 and 6. Calculations with improved staggered fermions have been performed
for various light to strange quark mass ratios in the range, 0.05 <= m_l/m_s <=
0.5, and with a strange quark mass fixed close to its physical value. From a
combined extrapolation to the chiral (m_l -> 0) and continuum (aT = 1/N_t -> 0)
limits we find for the transition temperature at the physical point T_c r_0 =
0.457(7) where the scale is set by the Sommer-scale parameter r_0 defined as
the distance in the static quark potential at which the slope takes on the
value, (dV_qq(r)/dr)_r=r_0 = 1.65/r_0^2. Using the currently best known value
for r_0 this translates to a transition temperature T_c = 192(7)(4)MeV. The
transition temperature in the chiral limit is about 3% smaller. We discuss
current ambiguities in the determination of T_c in physical units and also
comment on the universal scaling behavior of thermodynamic quantities in the
chiral limit.Comment: 18 pages, 14 EPS figures, replaced wrong entries in column 7 of Table
A.
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