3,003 research outputs found
Predicting the Next Best View for 3D Mesh Refinement
3D reconstruction is a core task in many applications such as robot
navigation or sites inspections. Finding the best poses to capture part of the
scene is one of the most challenging topic that goes under the name of Next
Best View. Recently, many volumetric methods have been proposed; they choose
the Next Best View by reasoning over a 3D voxelized space and by finding which
pose minimizes the uncertainty decoded into the voxels. Such methods are
effective, but they do not scale well since the underlaying representation
requires a huge amount of memory. In this paper we propose a novel mesh-based
approach which focuses on the worst reconstructed region of the environment
mesh. We define a photo-consistent index to evaluate the 3D mesh accuracy, and
an energy function over the worst regions of the mesh which takes into account
the mutual parallax with respect to the previous cameras, the angle of
incidence of the viewing ray to the surface and the visibility of the region.
We test our approach over a well known dataset and achieve state-of-the-art
results.Comment: 13 pages, 5 figures, to be published in IAS-1
Active Perception using Light Curtains for Autonomous Driving
Most real-world 3D sensors such as LiDARs perform fixed scans of the entire
environment, while being decoupled from the recognition system that processes
the sensor data. In this work, we propose a method for 3D object recognition
using light curtains, a resource-efficient controllable sensor that measures
depth at user-specified locations in the environment. Crucially, we propose
using prediction uncertainty of a deep learning based 3D point cloud detector
to guide active perception. Given a neural network's uncertainty, we derive an
optimization objective to place light curtains using the principle of
maximizing information gain. Then, we develop a novel and efficient
optimization algorithm to maximize this objective by encoding the physical
constraints of the device into a constraint graph and optimizing with dynamic
programming. We show how a 3D detector can be trained to detect objects in a
scene by sequentially placing uncertainty-guided light curtains to successively
improve detection accuracy. Code and details can be found on the project
webpage: http://siddancha.github.io/projects/active-perception-light-curtains.Comment: Published at the European Conference on Computer Vision (ECCV), 202
Mechanical Strength of 17 134 Model Proteins and Cysteine Slipknots
A new theoretical survey of proteins' resistance to constant speed stretching
is performed for a set of 17 134 proteins as described by a structure-based
model. The proteins selected have no gaps in their structure determination and
consist of no more than 250 amino acids. Our previous studies have dealt with
7510 proteins of no more than 150 amino acids. The proteins are ranked
according to the strength of the resistance. Most of the predicted top-strength
proteins have not yet been studied experimentally. Architectures and folds
which are likely to yield large forces are identified. New types of potent
force clamps are discovered. They involve disulphide bridges and, in
particular, cysteine slipknots. An effective energy parameter of the model is
estimated by comparing the theoretical data on characteristic forces to the
corresponding experimental values combined with an extrapolation of the
theoretical data to the experimental pulling speeds. These studies provide
guidance for future experiments on single molecule manipulation and should lead
to selection of proteins for applications. A new class of proteins, involving
cystein slipknots, is identified as one that is expected to lead to the
strongest force clamps known. This class is characterized through molecular
dynamics simulations.Comment: 40 pages, 13 PostScript figure
Current status of NLTE analysis of stellar atmospheres
Various available codes for NLTE modeling and analysis of hot star spectra
are reviewed. Generalizations of standard equations of kinetic equilibrium and
their consequences are discussed.Comment: in Determination of Atmospheric Parameters of B-, A-, F- and G-Type
Stars, E. Niemczura et al. eds., Springer, in pres
Governors and directors: Competing models of corporate governance
Why do we use the term ‘corporate governance’ rather than ‘corporate direction’? Early British joint stock companies were normally managed by a single ‘governor’. The ‘court of governors’ or ‘board of directors’ emerged slowly as the ruling body for companies. By the nineteenth century, however, companies were typically run by directors while not-for-profit entities such as hospitals, schools and charitable bodies had governors. The nineteenth century saw steady refinement of the roles of company directors, often in response to corporate scandals, with a gradual change from the notion of the director as a ‘representative shareholder’ to the directors being seen collectively as ‘representatives of the shareholders’. Governors in not-for-profit entities, however, were regarded as having broader responsibilities. The term ‘governance’ itself suggests that corporate boards should be studied as ‘political’ entities rather than merely through economic lenses such as agency theory
Electro-Magnetic Nucleon Form Factors and their Spectral Functions in Soliton Models
It is demonstrated that in simple soliton models essential features of the
electro-magnetic nucleon form factors observed over three orders of magnitude
in momentum transfer are naturally reproduced. The analysis shows that
three basic ingredients are required: an extended object, partial coupling to
vector mesons, and relativistic recoil corrections. We use for the extended
object the standard skyrmion, one vector meson propagator for both isospin
channels, and the relativistic boost to the Breit frame. Continuation to
timelike leads to quite stable results for the spectral functions in the
regime from the 2- or 3-pion threshold to about two rho masses. Especially the
onset of the continuous part of the spectral functions at threshold can be
reliably determined and there are strong analogies to the results imposed on
dispersion theoretic approaches by the unitarity constraint.Comment: 24 pages, (RevTeX), 5 PS-figures; Data points in fig.2 and
corresponding references added. Final version, to be published in Z.Physik
Photo-stability study of a solution-processed small molecule solar cell system: correlation between molecular conformation and degradation
<p>Solution-processed organic small molecule solar cells (SMSCs) have achieved efficiency over 11%. However, very few studies have focused on their stability under illumination and the origin of the degradation during the so-called burn-in period. Here, we studied the burn-in period of a solution-processed SMSC using benzodithiophene terthiophene rhodamine:[6,6]-phenyl C<sub>71</sub> butyric acid methyl ester (BTR:PC<sub>71</sub>BM) with increasing solvent vapour annealing time applied to the active layer, controlling the crystallisation of the BTR phase. We find that the burn-in behaviour is strongly correlated to the crystallinity of BTR. To look at the possible degradation mechanisms, we studied the fresh and photo-aged blend films with grazing incidence X-ray diffraction, UV–vis absorbance, Raman spectroscopy and photoluminescence (PL) spectroscopy. Although the crystallinity of BTR affects the performance drop during the burn-in period, the degradation is found not to originate from the crystallinity changes of the BTR phase, but correlates with changes in molecular conformation – rotation of the thiophene side chains, as resolved by Raman spectroscopy which could be correlated to slight photobleaching and changes in PL spectra.</p
Influence of irrigant needle depth in removing bioluminescent bacteria inoculated into instrumented root canals using real-time imaging in vitro
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73506/1/j.1365-2591.2004.00906.x.pd
Determinants and impact of role-related time use allocation on self-reported health among married men and women: a cross-national comparative study
Background Research on the effects of marriage on health maintains that there is a gender-specific gradient, with men deriving far greater benefits than women. One reason provided for this difference is the disproportionate amount of time spent by women on housework and childcare. However, this hypothesis has yet to be explicitly tested for these role-related time use activities. This study provides empirical evidence on the association between role-related time use activities (i.e. housework, childcare and paid work) and self-reported health among married men and women.
Methods Data from the Multinational Time Use Study (MTUS) on 32,881 men and 26,915 women from Germany, Italy, Spain, the UK and the US were analyzed. Seemingly unrelated regression (SUR) models and multivariable logistic regression were used to estimate the association between role-related time use activities and self-reported health among married men and women.
Results The findings showed that education, occupation and number of children under 18 years old in the household were the most consistent predictors of time allocation among married men and women. Significant gender differences were also found in time allocation, with women sacrificing paid working time or reducing time devoted to housework for childcare. Men, in contrast, were less likely to reduce paid working hours to increase time spent on childcare, but instead reduced time allocation to housework. Allocating more time to paid work and childcare was associated with good health, whereas time spent on housework was associated with poor health, especially among women.
Conclusions Time allocation to role-related activities have differential associations on health, and the effects vary by gender and across countries. To reduce the gender health gap among married men and women, public policies need to take social and gender roles into account
A preliminary study of genetic factors that influence susceptibility to bovine tuberculosis in the British cattle herd
Associations between specific host genes and susceptibility to Mycobacterial infections such as tuberculosis have been reported in several species. Bovine tuberculosis (bTB) impacts greatly the UK cattle industry, yet genetic predispositions have yet to be identified. We therefore used a candidate gene approach to study 384 cattle of which 160 had reacted positively to an antigenic skin test (‘reactors’). Our approach was unusual in that it used microsatellite markers, embraced high breed diversity and focused particularly on detecting genes showing heterozygote advantage, a mode of action often overlooked in SNP-based studies. A panel of neutral markers was used to control for population substructure and using a general linear model-based approach we were also able to control for age. We found that substructure was surprisingly weak and identified two genomic regions that were strongly associated with reactor status, identified by markers INRA111 and BMS2753. In general the strength of association detected tended to vary depending on whether age was included in the model. At INRA111 a single genotype appears strongly protective with an overall odds ratio of 2.2, the effect being consistent across nine diverse breeds. Our results suggest that breeding strategies could be devised that would appreciably increase genetic resistance of cattle to bTB (strictly, reduce the frequency of incidence of reactors) with implications for the current debate concerning badger-culling
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