2,365 research outputs found
Quantum Pieri rules for isotropic Grassmannians
We study the three point genus zero Gromov-Witten invariants on the
Grassmannians which parametrize non-maximal isotropic subspaces in a vector
space equipped with a nondegenerate symmetric or skew-symmetric form. We
establish Pieri rules for the classical cohomology and the small quantum
cohomology ring of these varieties, which give a combinatorial formula for the
product of any Schubert class with certain special Schubert classes. We also
give presentations of these rings, with integer coefficients, in terms of
special Schubert class generators and relations.Comment: 59 pages, LaTeX, 6 figure
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Increased baseline ECG R-R dispersion predicts improvement in systolic function after atrial fibrillation ablation.
BackgroundAtrial fibrillation (AF) is associated with left ventricular (LV) systolic dysfunction which may improve after AF ablation. We hypothesised that increased ventricular irregularity, as measured by R-R dispersion on the baseline ECG, would predict improvement in the left ventricular ejection fraction (LVEF) after AF ablation.MethodsPatients with LVEF <50% at two US centres (2007-2016), having both a preablation and postablation echocardiogram or cardiac MRI, were included. LVEF improvement was defined as absolute increase in LVEF by >7.5%. Multivariable logistic regression (restricted to echocardiographic/ECG variables) was performed to evaluate predictors of LVEF improvement.ResultsFifty-two patients were included in this study. LVEF improved in 30 patients (58%) and was unchanged/worsened in 22 patients (42%). Those with versus without LVEF improvement had an increased baseline R-R dispersion (645±155 ms vs 537±154 ms, p=0.02, respectively). The average baseline heart rate in all patients was 93 beats per minute. After multivariable logistic regression, increased R-R dispersion (OR 1.59, 95% CI 1.00 to 2.55, p=0.03) predicted LVEF improvement.ConclusionsIncreased R-R dispersion on ECG was independently associated with improved systolic function after AF ablation. This broadens the existing knowledge of arrhythmia-induced cardiomyopathy, demonstrating that irregular electrical activation (as measured by increased R-R dispersion on ECG) is associated with a cardiomyopathy capable of improving after AF ablation
Multi-View Object Instance Recognition in an Industrial Context
We present a fast object recognition system coding shape by viewpoint invariant geometric relations and appearance information. In our advanced industrial work-cell, the system can observe the work space of the robot by three pairs of Kinect and stereo cameras allowing for reliable and complete object information. From these sensors, we derive global viewpoint invariant shape features and robust color features making use of color normalization techniques.
We show that in such a set-up, our system can achieve high performance already with a very low number of training samples, which is crucial for user acceptance and that the use of multiple views is crucial for performance. This indicates that our approach can be used in controlled but realistic industrial contexts that require—besides high reliability—fast processing and an intuitive and easy use at the end-user side.European UnionDanish Council for Strategic Researc
Big Banks and Macroeconomic Outcomes: Theory and Cross-Country Evidence of Granularity
Does the mere presence of big banks affect macroeconomic outcomes? Gabaix (2011) shows that idosyncratic shocks can have aggregate effects if the distribution of firm sizes in manufacturing follows a power law distribution. Our contribution is two-fold. First, we expand the theory of granularity to encompass the Bertrand competition frequently used in models of banking. Using a model with banks of heterogenous size who charge endogenous markups, we show under which conditions granular effects emerge. Second, we empirically assess the relevance of granularity effects in banking using a linked micro-macro dataset of more than 80 countries for the years 1996-2009. We show that the banking sector is granular, i.e. the right tail of the bank size distribution follows a power law. Also, the presence of big banks as measured by high market concentration magnifies the effect of idiosyncratic shocks on loan growth. Through this channel, idiosyncratic shocks affecting large banks impact upon macroeconomic outcomes. This effect is particularly important for countries with less developed banking systems
Using Surfaces and Surface Relations in an Early Cognitive Vision System
The final publication is available at Springer via http://dx.doi.org/10.1007/s00138-015-0705-yWe present a deep hierarchical visual system with two parallel hierarchies for edge and surface information. In the two hierarchies, complementary visual information is represented on different levels of granularity together with the associated uncertainties and confidences. At all levels, geometric and appearance information is coded explicitly in 2D and 3D allowing to access this information separately and to link between the different levels. We demonstrate the advantages of such hierarchies in three applications covering grasping, viewpoint independent object representation, and pose estimation.European Community’s Seventh Framework Programme FP7/IC
Privacy-Constrained Biometric System for Non-cooperative Users
With the consolidation of the new data protection regulation paradigm for each individual within the European Union (EU), major biometric technologies are now confronted with many concerns related to user privacy in biometric deployments. When individual biometrics are disclosed, the sensitive information about his/her personal data such as financial or health are at high risk of being misused or compromised. This issue can be escalated considerably over scenarios of non-cooperative users, such as elderly people residing in care homes, with their inability to interact conveniently and securely with the biometric system. The primary goal of this study is to design a novel database to investigate the problem of automatic people recognition under privacy constraints. To do so, the collected data-set contains the subject's hand and foot traits and excludes the face biometrics of individuals in order to protect their privacy. We carried out extensive simulations using different baseline methods, including deep learning. Simulation results show that, with the spatial features extracted from the subject sequence in both individual hand or foot videos, state-of-the-art deep models provide promising recognition performance
Exact results for hydrogen recombination on dust grain surfaces
The recombination of hydrogen in the interstellar medium, taking place on
surfaces of microscopic dust grains, is an essential process in the evolution
of chemical complexity in interstellar clouds. The H_2 formation process has
been studied theoretically, and in recent years also by laboratory experiments.
The experimental results were analyzed using a rate equation model. The
parameters of the surface, that are relevant to H_2 formation, were obtained
and used in order to calculate the recombination rate under interstellar
conditions. However, it turned out that due to the microscopic size of the dust
grains and the low density of H atoms, the rate equations may not always apply.
A master equation approach that provides a good description of the H_2
formation process was proposed. It takes into account both the discrete nature
of the H atoms and the fluctuations in the number of atoms on a grain. In this
paper we present a comprehensive analysis of the H_2 formation process, under
steady state conditions, using an exact solution of the master equation. This
solution provides an exact result for the hydrogen recombination rate and its
dependence on the flux, the surface temperature and the grain size. The results
are compared with those obtained from the rate equations. The relevant length
scales in the problem are identified and the parameter space is divided into
two domains. One domain, characterized by first order kinetics, exhibits high
efficiency of H_2 formation. In the other domain, characterized by second order
kinetics, the efficiency of H_2 formation is low. In each of these domains we
identify the range of parameters in which, the rate equations do not account
correctly for the recombination rate. and the master equation is needed.Comment: 23 pages + 8 figure
The Healthy Start project: a randomized, controlled intervention to prevent overweight among normal weight, preschool children at high risk of future overweight
BACKGROUND: Research shows that obesity prevention has to start early. Targeting interventions towards subgroups of individuals who are predisposed, but yet normal weight, may prove more effective in preventing overweight than interventions towards unselected normal weight subsets. Finally, interventions focused on other factors than diet and activity are lacking. The objectives were to perform a randomized, controlled intervention aiming at preventing overweight in children aged 2–6 years, who are yet normal weight, but have high predisposition for future overweight, and to intervene not only by improving diet and physical activity, but also reduce stress and improve sleep quality and quantity. METHODS/DESIGN: Based on information from the Danish National Birth Registry and administrative birth forms, children were selected based on having either a high birth weight, a mother who was overweight prior to pregnancy, or a familial low socioeconomic status. Selected children (n = 5,902) were randomized into three groups; an intervention group, a shadow control group followed in registers exclusively, and a control group examined at the beginning and at the end of the intervention. Approximately 21% agreed to participate. Children who presented as overweight prior to the intervention were excluded from this study (n = 92). In the intervention group, 271 children were included, and in the control group 272 were included. Information obtained from the shadow control group is on-going, but it is estimated that 394 children will be included. The intervention took place over on average 1½ year between 2009 and 2011, and consisted of optional individual guidance in optimizing diet and physical activity habits, reducing chronic stress and stressful events and improving sleep quality and quantity. The intervention also included participation in cooking classes and play arrangements. Information on dietary intake, meal habits, physical activity, sleep habits, and overall stress level was obtained by 4–7 day questionnaire diaries and objective measurements. DISCUSSION: If the Healthy Start project is effective in preventing excessive weight gain, it will provide valuable information on new determinants of obesity which should be considered in future interventions, and on new strategies to prevent development of overweight and obesity at an early age. TRIAL REGISTRATION: ClinicalTrials.gov, ID NCT01583335
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