• 제목/요약/키워드: Aristotle

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아리스토텔레스 이전 시대의 기상학에 대해서 (On the Meteorology of Pre-age of Aristotle)

  • 윤일희
    • 과학교육연구지
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    • 제38권1호
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    • pp.96-102
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    • 2014
  • 기상학이란 학문은 어느 날 갑자기 출현한 것은 아니다. 맨 처음 기상학을 학문으로 구체화시킨 사람은 그리스 자연철학자인 아리스토텔레스였다. 공통기원이전 340년 경 발간된 아리스토텔레스의 유명한 논문집인 "Meteorologica"에서는 여러 가지 기상현상들을 설명하고 있다. 이 논문집의 제목이 기상학(meteorology)의 어원이 되었다. "기상론"이 아리스토텔레스의 이론을 대표할 뿐만 아니라 그 당시 역사학자, 철학자, 서사시와 더불어 그 당시의 지식들을 집대성한 것이기 때문에, 아리스토텔레스가 역사적으로 중요한 기상학 책을 집필할 수 있게 된 과학적인 배경을 살펴보는 것이 이 논문의 목적이다.

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아리스토텔레스의 무한론에 대한 제논의 역할 (The role of Zeno on the infinite of Aristotle)

  • 강대원;김권욱
    • 한국수학사학회지
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    • 제22권1호
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    • pp.1-24
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    • 2009
  • 본 논문에서는 아리스토텔레스의 무한론과 제논의 논증들과 역설에 대한 그의 논의를 기반으로 아리스토텔레스의 잠재적인 무한론 형성에 제논의 영향을 추론하였다. 고대 그리스수학의 기초로서 아리스토텔레스의 잠재적인 무한을 고찰해 보면 미적분학에 꼭 필요한 실무한에 대한 개념을 허락하지 않았다. 아리스토텔레스의 "자연학"에서 실무한의 존재를 부정하고 잠재적인 무한만을 주장하게 된 것은 제논의 논증에 나타난 불합리를 피하기 위한 희망이 내재해 있는 것으로 판단할 수 있다. 따라서 고대 그리스인들이 왜 실제적으로 극한 개념을 수반한 적분을 개발하지 못하고 번거롭고 불완전한 십진법을 사용하면서 멀리까지 왔는지에 대한 이유 중 하나를 제공할 수 있을 것이다.

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Laminin-1 Phosphorylation by Protein Kinase A: Effect on self assembly and heparin binding

  • Koliakos, George;Kouzi-Koliakos, Kokkona;Triantos, Athanasios;Trachana, Varvara;Kavoukopoulos, Evaggelos;Gaitatzi, Mary;Dimitriadou, Aphrodite
    • BMB Reports
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    • 제33권5호
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    • pp.370-378
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    • 2000
  • Incubation of purified laminin1-nidogen1 complexes with $[{\gamma}-^{32}P]-ATP$ in the presence of the catalytic subunit of the protein kinase A (cAMP-dependent protein kinase) resulted in the phosphorylation of the alpha chain of laminin-1 and of the nidogen-1 molecule. Aminoacid electrophoresis indicated that phosphate was incorporated on serine residues. The phosphorylation effect of laminin-1 on the process of self assembly was studied by turbidometry. In these experiments, the phosphorylated laminin-1 showed a reduced maximal aggregation capacity in comparison to the non-phosphorylated molecule. Examination of the laminin-1 network under the electron microscope showed that the phosphorylated sample formed mainly linear extended oligomers, in contrast to controls that formed large and dense multimeric aggregates. Heparin binding on phosphorylated laminin-1 in comparison to controls was also tested using solid-phase binding assays. The results indicated an enhanced heparin binding to the phosphorylated protein. The results of this study indicate that laminin1-nidogen1 is a substrate for protein kinase A in vitro. This phosphorylation had an obvious influence on the lamininl-nidogen1 network formation and the heparin binding capacity of this molecule. However, further studies are needed to investigate whether or not this phenomenon could play a role in the formation of the structure of basement membranes in vivo.

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Development of comprehensive earthquake loss scenarios for a Greek and a Turkish city: seismic hazard, geotechnical and lifeline aspects

  • Pitilakis, Kyriazis D.;Anastasiadis, Anastasios I.;Kakderi, Kalliopi G.;Manakou, Maria V.;Manou, Dimitra K.;Alexoudi, Maria N.;Fotopoulou, Stavroula D.;Argyroudis, Sotiris A.;Senetakis, Kostas G.
    • Earthquakes and Structures
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    • 제2권3호
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    • pp.207-232
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    • 2011
  • The development of reliable earthquake mitigation plans and seismic risk management procedures can only be based on the establishment of comprehensive earthquake hazard and loss scenarios. Two cities, Grevena (Greece) and D$\ddot{u}$zce (Turkey), were used as case studies in order to apply a comprehensive methodology for the vulnerability and loss assessment of lifelines. The methodology has the following distinctive phases: detailed inventory, identification of the typology of each component and system, evaluation of the probabilistic seismic hazard, geotechnical zonation, ground response analysis and estimation of the spatial distribution of seismic motion for different seismic scenarios, vulnerability analysis of the exposed elements at risk. Estimating adequate earthquake scenarios for different mean return periods, and selecting appropriate vulnerability functions, expected damages of the water and waste water systems in D$\ddot{u}$zce and of the roadway network and waste water system of Grevena are estimated and discussed; comparisons with observed earthquake damages are also made in the case of D$\ddot{u}$zce, proving the reliability and the efficiency of the proposed methodology. The results of the present study constitute a sound basis for the development of efficient loss scenarios for lifelines and infrastructure facilities in seismic prone areas. The first part of this paper, concerning the estimation of the seismic ground motions, has been utilized in the companion paper by Kappos et al. (2010) in the same journal.

Prognostic Factors in Patients Treated with DrugCoated Balloon Angioplasty for Symptomatic Peripheral Artery Disease

  • Sigala, Fragiska;Galyfos, George;Stavridis, Kyriakos;Tigkiropoulos, Konstantinos;Lazaridis, Ioannis;Karamanos, Dimitrios;Mpontinis, Vangelis;Melas, Nikolaos;Zournatzi, Ioulia;Filis, Konstantinos;Saratzis, Nikolaos
    • Vascular Specialist International
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    • 제34권4호
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    • pp.94-102
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    • 2018
  • Purpose: Aim of this study is to report real-life experience on the treatment of peripheral artery disease (PAD) with a specific drug-coated balloon (DCB), and to evaluate potential prognostic factors for outcomes. Materials and Methods: This is a retrospective study reporting outcomes in patients with PAD who were treated with the Lutonix DCB during a four-year period. Major outcomes included: all-cause mortality, amputation, clinical improvement, wound healing and target lesion revascularization (TLR). Mean follow-up was $24.2{\pm}2.3$ months. Results: Overall, 149 patients (mean age: $68.6{\pm}8.3$ years; 113 males) were treated, either for intermittent claudication (IC) (n=86) or critical limb ischemia (CLI) (n=63). More than half the target lesions (n=206 in total) were located in the superficial femoral artery and 18.0% were below-the-knee lesions. CLI patients presented more frequently with infrapopliteal (P=0.002) or multilevel disease (P=0.0004). Overall, all-cause mortality during follow-up was 10.7%, amputation-free survival was 81.2% and TLR-free survival was 96.6%. CLI patients showed higher all-cause mortality (P=0.007) and total amputation (P=0.0001) rates as well as lower clinical improvement (P=0.0002), compared to IC patients. Coronary artery disease (CAD), gangrene and infrapopliteal disease were found to be predictors for death whereas CLI and gangrene were found to be predictors for amputation, during follow-up. Conclusion: PAD treatment with Lutonix DCBs seems to be an efficient and safe endovascular strategy yielding promising results. However, CAD, gangrene, CLI and infrapopliteal lesions were found to be independent predictors for adverse outcomes. Larger series are needed to identify additional prognostic factors.

Development of comprehensive earthquake loss scenarios for a Greek and a Turkish city - structural aspects

  • Kappos, A.J.;Panagopoulos, G.K.;Sextos, A.G.;Papanikolaou, V.K.;Stylianidis, K.C.
    • Earthquakes and Structures
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    • 제1권2호
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    • pp.197-214
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    • 2010
  • The paper presents a methodology for developing earthquake damage and loss scenarios for urban areas, as well as its application to two cities located in Mediterranean countries, Grevena (in Greece) and D$\ddot{u}$zce (in Turkey), that were struck by strong earthquakes in the recent past. After compiling the building inventory in each city, fragility curves were derived using a hybrid approach previously developed by the authors, and a series of seismic scenarios were derived based on microzonation studies that were specifically conducted for each city (see companion paper by Pitilakis et al.). The results obtained in terms of damage estimates, required restoration times and the associated costs are presented in a GIS environment. It is deemed that both the results obtained, and the overall methodology and tools developed, contribute towards the enhancement of seismic safety in the Mediterranean area (as well as other earthquake-prone regions), while they constitute a useful pre-earthquake decision-making tool for local authorities.

Epistaxis in dental and maxillofacial practice: a comprehensive review

  • Psillas, George;Dimas, Grigorios Georgios;Papaioannou, Despoina;Savopoulos, Christos;Constantinidis, Jiannis
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • 제48권1호
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    • pp.13-20
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    • 2022
  • The lifetime incidence of epistaxis in dental and maxillofacial practice has been reported to be as high as 60% and can be caused by dental implant placement, Le Fort I osteotomy, intranasal supernumerary tooth, odontogenic tumors, blood disorders and maxillofacial trauma. Most epistaxis cases are minor and easily managed with direct compression on the nares for 10 minutes. For more significant or recurrent epistaxis, other techniques might include electrocautery, anterior or posterior nasal packing, or Foley catheter balloon. For patients with refractory epistaxis, cauterization of the sphenopalatine artery under endonasal endoscopy or embolization of the internal maxillary artery should be performed. Epistaxis control is required in patients diagnosed with inherited or acquired bleeding disorders or with drug-induced coagulopathies during dental procedures. In these cases, hemostatic system adjustment and hemostasis achieved by local and adjunctive methods are required. Dentists and maxillofacial surgeons must be aware that the nasal cavity is a potential source of perioperative hemorrhage. Depending on the invasiveness of the dental intervention, preoperative involvement of the hematologist and cardiologist is usually necessary to reverse anticoagulation or to cease anticoagulant therapy.

A Study on the Ancient Greek Physical Education Spirit

  • Han, Do Ryung
    • 한국컴퓨터정보학회논문지
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    • 제22권4호
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    • pp.99-105
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    • 2017
  • Plato and Aristotle examined what the true spirit of physical education is and what kind of relationship it is, from the perspective of dividing into two parts of the body and mind. And the relationship between human body and mind, knowledge and behavior. Plato and Aristotle examined the harmonious combination of body and mind and what is the desirable relationship setting. In Plato's soul and body in philosophical centered ideological aspect, human education center emphasizes poetry education, but physical education is recognized as essential education for human education. Plato's body contour emphasizes the harmony of soul and body, not the superiority of the body to the mind. In Plato's education room, physical education should be preceded and then mental education should be done. I thought that there could be no independent souls without bodies. It is not an independent entity but a unified entity. Because there is a body, there is a soul. There is a soul, so a body exists. Aristotle thought that the body was more important than Plato, and that the body should be preceded by the soul.