A finite presentation for the twist subgroup of the mapping class group of a nonorientable surface

Micha\l\ Stukow 대한수학회 2016 대한수학회보 Vol.53 No.2

Let $N_{g,s}$ denote the nonorientable surface of genus $g$ with $s$ boundary components. Recently Paris and Szepietowski \cite{SzepParis} obtained an explicit finite presentation for the mapping class group $\cM(N_{g,s})$ of the surface $N_{g,s}$, where $s\in\{0,1\}$ and $g+s>3$. Following this work, we obtain a finite presentation for the subgroup $\cT(N_{g,s})$ of $\cM(N_{g,s})$ generated by Dehn twists.

Dual-Energy CT Angiography Improves Accuracy of Spot Sign for Predicting Hematoma Expansion in Intracerebral Hemorrhage

Michaël T.J. Peeters,Kim J.D. de Kort,Rik Houben,Wouter J.P. Henneman,Robert J. van Oostenbrugge,Julie Staals,Alida A. Postma 대한뇌졸중학회 2021 Journal of stroke Vol.23 No.1

Background and Purpose: Spot sign (SS) on computed tomography angiography (CTA) is associated with hematoma expansion (HE) and poor outcome after intracerebral hemorrhage (ICH). However, its predictive performance varies across studies, possibly because differentiating hyperdense hemorrhage from contrast media is difficult. We investigated whether dual-energy-CTA (DE-CTA),which can separate hemorrhage from iodinated contrast, improves the diagnostic accuracy of SS for predicting HE. Methods: Primary ICH patients undergoing DE-CTA (both arterial as well as delayed venous phase) and follow-up computed tomography were prospectively included between 2014 and 2019. SS was assessed on both arterial and delayed phase images of the different DE-CTA datasets, i.e., conventional-like mixed images, iodine images, and fusion images. Diagnostic accuracy of SS for prediction of HE was determined on all datasets. The association between SS and HE, and between SS and poor outcome (modified Rankin Scale at 3 months ≥3) was assessed with multivariable logistic regression, using the dataset with highest diagnostic accuracy. Results: Of 139 included patients, 47 showed HE (33.8%). Sensitivity of SS for HE was 32% (accuracy 0.72) on conventional-like mixed arterial images which increased to 76% (accuracy 0.80) on delayed fusion images. Presence of SS on delayed fusion images was independently associated with HE (odds ratio [OR], 17.5; 95% confidence interval [CI], 6.14 to 49.82) and poor outcome (OR, 3.84;95% CI, 1.16 to 12.73). Conclusions: Presence of SS on DE-CTA, in particular on delayed phase fusion images, demonstrates higher diagnostic performance in predicting HE compared to conventional-like mixed imaging, and it is associated with poor outcome.

Accurate initial conditions for cosmological N-body simulations

Michaël Michaux,Graziano Rossi 한국천문학회 2022 天文學會報 Vol.47 No.2

THE DIFFERENT IMPACTS OF DIFFERENT TYPES OF NATURAL RESOURCES ON POLITICAL INSTITUTIONS IN DEVELOPING COUNTRIES

MICHAËL GOUJON,ARISTIDE MABALI 중앙대학교 경제연구소 2016 Journal of Economic Development Vol.41 No.3

Rents generated by natural resources are usually thought to weaken the quality of institutions, particularly in developing countries. Our hypothesis is that this effect may differ depending on the types of natural resources characterized by their different degree of appropriability. We test this hypothesis using panel data covering 90 developing countries for the period 1970-2010. We find that total rents weaken the quality of institutions. However, while oil rents have a significant negative effect, forest and mineral rents do not, after controlling for the other relevant determinants of institutional quality, institutional persistence, neighbor effect, and endogeneity of rents.

PASTELS project - overall progress of the project on experimental and numerical activities on passive safety systems

Montout Michaël,Herer Christophe,Telkkä Joonas 한국원자력학회 2024 Nuclear Engineering and Technology Vol.56 No.3

Nuclear accidents such as Fukushima Daiichi have highlighted the potential of passive safety systems to replace or complement active safety systems as part of the overall prevention and/or mitigation strategies. In addition, passive systems are key features of Small Modular Reactors (SMRs), for which they are becoming almost unavoidable and are part of the basic design of many reactors available in today’s nuclear market. Nevertheless, their potential to significantly increase the safety of nuclear power plants still needs to be strengthened, in particular the ability of computer codes to determine their performance and reliability in industrial applications and support the safety demonstration. The PASTELS project (September 2020–February 2024), funded by the European Commission “Euratom H2020” programme, is devoted to the study of passive systems relying on natural circulation. The project focuses on two types, namely the SAfety COndenser (SACO) for the evacuation of the core residual power and the Containment Wall Condenser (CWC) for the reduction of heat and pressure in the containment vessel in case of accident. A specific design for each of these systems is being investigated in the project. Firstly, a straight vertical pool type of SACO has been implemented on the Framatome’s PKL loop at Erlangen. It represents a tube bundle type heat exchanger that transfers heat from the secondary circuit to the water pool in which it is immersed by condensing the vapour generated in the steam generator. Secondly, the project relies on the CWC installed on the PASI test loop at LUT University in Finland. This facility reproduces the thermal-hydraulic behaviour of a Passive Containment Cooling System (PCCS) mainly composed of a CWC, a heat exchanger in the containment vessel connected to a water tank at atmospheric pressure outside the vessel which represents the ultimate heat sink. Several activities are carried out within the framework of the project. Different tests are conducted on these integral test facilities to produce new and relevant experimental data allowing to better characterize the physical behaviours and the performances of these systems for various thermo-hydraulic conditions. These test programmes are simulated by different codes acting at different scales, mainly system and CFD codes. New “system/ CFD” coupling approaches are also considered to evaluate their potential to benefit both from the accuracy of CFD in regions where local 3D effects are dominant and system codes whose computational speed, robustness and general level of physical validation are particularly appreciated in industrial studies. In parallel, the project includes the study of single and two-phase natural circulation loops through a bibliographical study and the simulations of the PERSEO and HERO-2 experimental facilities. After a synthetic presentation of the project and its objectives, this article provides the reader with findings related to the physical analysis of the test results obtained on the PKL and PASI installations as well an overall evaluation of the capability of the different numerical tools to simulate passive systems.

Capability of Tungsten Carbide Micro-mills to Machine Hardened Tool Steel

Alexandre Gilbin,Michaël Fontaine,Gérard Michel,Sébastien Thibaud,Philippe Picard 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.

The aim of this study is to optimize micro-mills and their conditions of use to manufacture plastic injection molds in hardened tool steels by micro-milling. The presented results deal with the test of four types of tungsten carbide square end micro-mills in elementary operations with different feed rates and cutting speeds in order to analyze the evolution of cutting forces, cutting stability, tool life,tool wear, surface roughness and burs formation. This experimental approach allows highlighting the influence of cutting conditions,especially feed rate, on burr formation and tool life. This analysis shows a correlation between the micro-mills characteristics (geometry, composition of tungsten carbide) and their wear behavior. Moreover, some dynamic aspects of the micro-milling process are underlined through the influence of cutting speed on cutting stability. This type of experimental study is suitable for the optimization of the tool edge geometry and it reveals the need to develop a predictive model adapted to micro-milling to optimize the dynamic behavior of the tool.

Public-Private Partnerships for the Provision of Port Infrastructure: An Explorative Multi-Actor Perspective on Critical Success Factors

Geoffrey AERTS,Thies GRAGE,Michaël DOOMS,Elvira HAEZENDONCK 한국해운물류학회 2014 The Asian journal of shipping and Logistics Vol.30 No.3

Public-private cooperation on the level of project finance, and provision of large-scale infrastructure projects, is increasing on the global level. This paper uses a multi-actor analysis, in order to explore the critical success factors (CSFs) for sound implementation of public-private partnerships (PPPs) in the port context, and to determine the diverging opinions of stakeholders with regard to the importance of these CSFs. The results indicate that eight CSFs are of superior importance in port PPPs: the concreteness and preciseness of the concession agreement, the ability to appropriately allocate and share risk, the technical feasibility of the project, the commitment made by partners, the attractiveness of the financial package, a clear definition of responsibilities, the presence of a strong private consortium and a realistic cost/benefit assessment. The reason for their importance is their deal-breaking character, which can lead to a total failure of PPP projects during the early stages of project conception.

Composition of the Essential Oil of Bidens tripartita L. Roots and Its Antibacterial and Antifungal Activities

Monika Tomczykowa,Katarzyna Leszczyńska,Micha1 Tomczyk,El_zbieta Tryniszewska,Danuta Kalemba 한국식품영양과학회 2011 Journal of medicinal food Vol.14 No.4

The chemical composition of the essential oil obtained from the roots of Bidens tripartita L. by hydrodistillation was investigated by gas chromatography–mass spectrometry. In total, 106 compounds were identified (97.1% of the total oil). The main components of the oil were α-pinene (15.0%), β-bisabolene (9.3%), p-cymene (6.0%), hexanal (5.7%), linalool (4.6%), p-cymene-9-ol (3.4%), β-elemene (2.6%), 2-pentylfuran (2.2%), and silphiperfol-6-ene (2.1%). The antibacterial and antifungal properties of the essential oil were evaluated against eight Gram-positive and 11 Gram-negative bacterial species and 10 fungal strains. The oil exhibited a strong antifungal activity.

An unusual case of relapsing arrhythmia during veno-arterial extracorporeal membrane oxygenation cannulation

Ruth Van Lancker,Tim Balthazar,Stijn Lochy,Michaël Mekeirele 대한중환자의학회 2024 Acute and Critical Care Vol.39 No.1

PRESENTATIONS AND REPRESENTATIONS OF SURFACE SINGULAR BRAID MONOIDS

Micha l Jab lonowski 대한수학회 2017 대한수학회지 Vol.54 No.3

The surface singular braid monoid corresponds to marked graph diagrams of knotted surfaces in braid form. In a quest to resolve linearity problem for this monoid, we will show that if it is defined on at least two or at least three strands, then its two or respectively three dimensional representations are not faithful. We will also derive new presentations for the surface singular braid monoid, one with reduced the number of defining relations, and the other with reduced the number of its singular generators. We include surface singular braid formulations of all knotted surfaces in Yoshikawa's table.