Recurrent Surface Homeomorphisms

An orientation-preserving recurrent homeomorphism of the two-sphere which is not the identity is shown to admit exactly two fixed points. A recurrent homeomorphism of a compact surface with negative Euler characteristic is periodic.Comment: 10 pages LaTeX; fixed some reference

The impact of roads on poverty reduction : a case study of Cameroon

Many investments in infrastructure are built on the belief that they will ineluctably lead to poverty reduction and income generation. This has entailed massive aid-financed projects in roads in developing countries. However, the lack of robust evaluations and a comprehensive theoretical framework could raise questions about current strategies in Sub-Saharan Africa. Using the second Cameroonian national household survey (Enquete Camerounaise Aupres des Menages II, 2001) and the Cameroon case study, this paper demonstrates that investing uniformly in tarred roads in Africa is likely to have a much lower impact on poverty than expected. Isolation from a tarred road is found to have no direct impact on consumption expenditures in Cameroon. The only impact is an indirect one in the access to labor activities. This paper reasserts the fact that access to roads is only one factor contributing to poverty reduction (and not necessarily the most important in many cases). Considering that increase in non-farming activities is the main driver for poverty reduction in rural Africa, the results contribute to the idea that emphasis on road investments should be given to locations where non-farming activities could be developed, which does mean that the last mile in rural areas probably should not be a road.Transport Economics Policy&Planning,Rural Poverty Reduction,Regional Economic Development,Achieving Shared Growth

New Insight on the Performance of Equity Long/short Investment Styles

peer reviewedLong-short equity strategies have recently generated exceptional performance raising a set of concerns about the strategies’ propensity to deliver alpha or beta. This paper revisits the performance of equity long-short hedge funds across investments styles. We first categorize individual hedge funds with regard to their size and/or value factor investing along the generalization of Sharpe (1992) style analysis. Style weights on size and value factors are used to split the equity long-short universe in 5x5 hedge fund style portfolios. To analyze the performance of each style, we consider two sets of innovative factors. First, we apply sequential Fama-French model of Lambert, Fays and Hübner (2015). Besides, to captures downside and extreme risk embedded in hedge fund strategies we augment the model with the co-skewness and co-kurtosis factors developed by Lambert and Hübner (2013). Under this framework, we perform cross-sectional performance analyses of individual hedge funds as well as time-series analysis on the hedge fund style broad category. Our contributions are threefold; first, our alternative framework significantly improves the explanatory power of the multi-factor model in the context of long-short equity funds, second, considering higher-moment factors aim to capture part of the abnormal return of the downside and extreme risk exposures taken by a fund manager, and finally, long-short equity hedge funds are, to some extent, less exposed to small capitalisation stocks than expected and instead rather prefer higher momentum levels in their strategies.Hedge funds special editio

FINDING EEG SPACE-TIME-SCALE LOCALIZED FEATURES USING MATRIX-BASED PENALIZED DISCRIMINANT ANALYSIS

International audienceThis paper proposes a new method for constructing and selecting of discriminant space-time-scale features for electroencephalogram (EEG) signal classification, suitable for Error Related Potentials (ErrP)detection in brain-computer interface (BCI). The method rests on a new variant of matrix-variate Linear Discriminant Analysis (LDA), and differs from previously proposed approaches in mainly three ways. First, a discrete wavelet expansion is introduced for mapping time-courses to time-scale coefficients, yielding time-scale localized features. Second, the matrix-variate LDA is modified in such a way that it yields an interesting duality property, that makes interpretation easier. Third, a space penalization is introduced using a surface Laplacian, so as to enforce spatial smoothness. The proposed approaches, termed D-MLDA and D-MPDA are tested on EEG signals, with the goal of detecting ErrP. Numerical results show that D-MPDA outperforms D-MLDA and other matrix-variate LDA techniques. In addition this method produces relevant features for interpretation in ErrP signals

Sensor technology in sheep on range pastures to monitor health and welfare

The future aim is to develop a system for automatick real-time monitoring of physiological health indicators of farm animals to ensure and improve individual health and welfare and productivity. The main objective of the current project is to evaluate if sensors that measure temperature and heartrate can be used for early detecction of disease and predatory attack

First IJCAI International Workshop on Graph Structures for Knowledge Representation and Reasoning (GKR@IJCAI'09)

International audienceThe development of effective techniques for knowledge representation and reasoning (KRR) is a crucial aspect of successful intelligent systems. Different representation paradigms, as well as their use in dedicated reasoning systems, have been extensively studied in the past. Nevertheless, new challenges, problems, and issues have emerged in the context of knowledge representation in Artificial Intelligence (AI), involving the logical manipulation of increasingly large information sets (see for example Semantic Web, BioInformatics and so on). Improvements in storage capacity and performance of computing infrastructure have also affected the nature of KRR systems, shifting their focus towards representational power and execution performance. Therefore, KRR research is faced with a challenge of developing knowledge representation structures optimized for large scale reasoning. This new generation of KRR systems includes graph-based knowledge representation formalisms such as Bayesian Networks (BNs), Semantic Networks (SNs), Conceptual Graphs (CGs), Formal Concept Analysis (FCA), CPnets, GAI-nets, all of which have been successfully used in a number of applications. The goal of this workshop is to bring together the researchers involved in the development and application of graph-based knowledge representation formalisms and reasoning techniques

Reverse Engineering of Temporal Queries Mediated by LTL Ontologies

In reverse engineering of database queries, we aim to construct a query from a given set of answers and non-answers; it can then be used to explore the data further or as an explanation of the answers and non-answers. We investigate this query-by-example problem for queries formulated in positive fragments of linear temporal logic LTL over timestamped data, focusing on the design of suitable query languages and the combined and data complexity of deciding whether there exists a query in the given language that separates the given answers from non-answers. We consider both plain LTL queries and those mediated by LTL-ontologies.Comment: To be published in IJCAI 2023 proceeding

Pharmacokinetic parameters of artesunate and dihydroartemisinin in rats infected with Fasciola hepatica

Objectives The pharmacokinetic (PK) parameters of artesunate, recently discovered to possess promising trematocidal activity, and its main metabolite dihydroartemisinin (DHA) were determined in rats infected with hepatic and biliary stages of Fasciola hepatica and compared with uninfected rats after single intragastric and intravenous (iv) doses. Methods Rats infected with F. hepatica for 25 and 83 days and uninfected rats were cannulated in the right jugular vein and blood samples were withdrawn at selected timepoints following 10 mg/kg of iv and a single 100 mg/kg oral dose of artesunate. Plasma was analysed for artesunate and DHA by liquid chromatography coupled to tandem mass spectrometry. Results Rats harbouring juvenile and adult F. hepatica infections revealed considerable changes in PK parameters of artesunate and DHA. Following oral administration, maximum plasma concentrations (Cmax) of artesunate and DHA were 1.8-2.3-fold higher in infected rats [artesunate: 1334 ± 1404 ng/mL (no infection) versus 2454 ± 1494 ng/mL (acute infection) and 2768 ± 538 ng/mL (chronic infection); DHA: 3802 ± 2149 ng/mL (no infection) versus 6507 ± 3283 ng/mL (acute infection) and 9093 ± 884 ng/mL (chronic infection)]. The AUCs of artesunate and DHA were 2.1-4.4-fold greater in infected rats. An opposite trend was observed after iv injection. Cmax and AUC of artesunate and DHA following iv dosing were 5784 ± 3718 and 140 938 ± 128 783 ng·min/mL and 3849 ± 3060 and 86 107 ± 41 863 ng·min/mL, respectively, in uninfected rats versus 2623 ± 1554 and 21 617 ± 12 230 ng·min/mL and 2835 ± 980 and 64 290 ± 29 057 ng·min/mL, respectively, in rats harbouring a chronic infection. The elimination half-lives (t1/2) of artesunate and DHA were considerably altered in infected rats following oral and iv administration of artesunate. Conclusions F. hepatica infections strongly influence the disposition kinetics of artesunate and its metabolite in rats. The clinical implications of this finding need to be carefully studie

Unfolding Of Surfaces

This paper deals with the approximation of the unfolding of a smooth developpa- ble surface with a triangle mesh. First of all, we give an explicit approximat- ion of the unfolding of a smooth developable surface with the unfolding of a developable triangle mesh close to the smooth surface. The quality of the approximation depends on the maximal angle between the normals of the two surfaces and the relative curvature distance of the smooth surface (which is linked to the curvature of the smooth surface and the Hausdorff distance between the two surfaces). We give examples of sequences of developable triangle meshes inscribed on a sphere of radius 1, with a number of vertices and edges tending to infinity