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Almost complex manifolds from the point of view of Kodaira dimension
No full textIn complex geometry a classical and useful invariant of a complex manifold is its Kodaira dimension. Since its introduction by Iitaka in the early 70's, its behavior under deformations was object of study and it is known that Kodaira dimension is invariant under holomorphic deformations for smooth projective manifolds, while there are examples of holomorphic deformations of non-projective manifolds for which the Kodaira dimension is non-constant. Recently this concept has been generalized to almost complex manifolds, we want to present here some of its main features in the non-integrable case, mainly with respect to deformations. At the end we conclude with some speculations on the theory of meromorphic functions on almost complex manifolds
Dolbeault-Massey triple products of low degree
No full textLet A = (A(center dot,center dot), partial derivative(A)) be a differential bigraded algebra.
We characterize non-vanishing Dolbeault-Massey triple products of low degree (see Theorems 3.1 and 3.2).
We give some applications for the Dolbeault complex on a compact complex manifold
Kodaira dimension of almost Kähler manifolds and curvature of the canonical connection
Get PDFThe notion of Kodaira dimension has recently been extended to general almost complex manifolds. In this paper we focus on the Kodaira dimension of almost Kahler manifolds, providing an explicit computation for a family of almost Kahler threefolds on the differentiable manifold underlying a Nakamura manifold. We concentrate also on the link between Kodaira dimension and the curvature of the canonical connection of an almost Kahler manifold and show that in the previous example (and in another one obtained from a Kodaira surface) the Ricci curvature of the almost Kahler metric vanishes for all the members of the family
Complex symplectic structures and the ∂ ∂ ¯ -lemma
Get PDFIn this paper, we study complex symplectic manifolds, i.e., compact complex manifolds X which admit a holomorphic (2, 0)-form σ which is d-closed and non-degenerate, and in particular the Beauville–Bogomolov–Fujiki quadric Q_σ associated with them. We will show that if X satisfies the ∂∂ ̄ -lemma, then Q_σ is smooth if and only if h^(2,0)(X)=1 and is irreducible if and only if h^(1,1)(X)>0
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
CNN-based Pose Estimation to Assist Medical Imaging
No full textThe correct execution of scanning protocols is crucial to ensure the quality of radiographic examinations. Recent advances in machine learning methods have opened up new possibilities for medical imaging. However, the potential of pose estimation models in this field is still largely unexplored. This study aims to address this gap by investigating the performance and an application of pose estimation in the context of X-ray image acquisition. To this goal, a pose estimation model was selected from a pool of state-of-the-art models. It was then trained on a dataset of 213 images of humans undergoing X-ray imaging. Despite the limited size of the dataset, the model achieved an AP of 0.902 and a near real-time inference speed of 7 FPS on CPU. The detection of landmarks through pose estimation enables the automatic assessment of pose adherence to prescribed imaging protocols. This automation can reduce human errors and alleviate the mental workload on radiologists. The results of this study highlight the potential of convolutional neural network-based pose estimation models to assist radiologists in performing X-ray imaging tasks effectively
General Equilibrium Measures of Agricultural Policy Bias in Fifteen Developing Countries
Get PDFA comparative analysis of 15 developing countries shows that, during the 1990s, indirect taxes, tariffs, and exchange rates significantly discriminated against agriculture in only one country (Malawi), was largely neutral in five (Argentina, Brazil, Costa Rica, Indonesia, and Zimbabwe), provided a moderate subsidy to agriculture in four (Mexico, Tanzania, Venezuela, and Zambia), and strongly favored agriculture in five (Egypt, Korea, Morocco, Mozambique, and Tunisia). In contrast to earlier partial equilibrium results, our general equilibrium analysis indicates that exchange rate changes can lead to anything between strongly increasing and strongly decreasing relative agriculture/non-agriculture incentives, depending on relative trade shares and relative tradability of agricultural and non-agricultural commodities. Country-specific circumstances greatly affect the relative impact of trade policies on agriculture and the rest of the economy in a general equilibrium setting. Earlier partial equilibrium measures of policy bias could not adequately incorporate country heterogeneity and are therefore likely to have overstated the bias. In any case, from the empirical results with our sample of countries, we conclude that any incentive bias against agriculture in the 1980s had mostly disappeared by the 1990s.urban bias, food and agricultural policy; general equilibrium modelling
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