331,663 research outputs found
Keratoconus : current and future state-of-the-art
No full textThis book provides a practical guide to the most recent advances in the diagnostic management of corneal ectasia. Clear, concise chapters address new standardized nomograms of treatment of early progressive ectasia, new epithelium on future crosslinking with and without oxygen supplement, customized protocols, laser assisted corneal regularization protocols and the new femtolaser assisted lamellar corneal transplant. Clinicians and surgeons seeking a go-to guide on the topic of corneal ectasia will find this book to be an essential resource for the latest developments and predicted future trends in the field. © The Editor(s) (if applicable) and The Author(s)
A DAG-Based Forwarding Paradigm for Large Scale Software Defined Networks
No full textThe Software Defined Network (SDN) paradigm represents a major breakthrough in the networking field, due to its unprecedented capabilities in terms of flexibility and programmability. SDNs have been successfully deployed in data centers and small to medium enterprises. However, adopting the SDN paradigm in the context of wide area networks is more challenging, due to a number of factors including the higher probability that node and link failures occur and the unavailability of a dedicated control channel. In this paper, we present a DAG (Directed Acyclic Graph) based forwarding paradigm addressing the challenges that arise when the SDN concept is applied to large scale networks. Specifically, the proposed paradigm aims to limit the number of entries required on the SDN switches, to provide a fast local restoration of single node/link failures without the intervention of the SDN controller and to prevent the possibility of having inconsistent forwarding tables during updates. The proposed paradigm does not require any extension to the OpenFlow protocol and we show how it can be implemented by only using standard features. The DAG-based forwarding paradigm requires to compute a DAG between every pair of ingress-egress switches and to design an index-based hashing scheme to balance the load across the paths in the DAG while avoiding TCP reordering issues. In this paper, we present heuristic algorithms providing a solution to such problems and report the results of a simulation study conducted to assess the performance of the proposed forwarding paradigm
Al-Ashraf ʿumar’s Tabṣira. Chapter XXXVI: Rainfalls, Winds, and Agricultural Activities
No full textThis article presents a detailed study of Chapter xxxvi of Kitāb al-Tabṣira fī ʿilm al-nujūm (‘Enlightenment in the Science of the Stars’) by al-Ashraf ʿUmar, the future Rasūlid sultan of 13th-century Yemen. The chapter simultaneously addresses three interrelated topics: rains, agricultural activities, and winds. Beyond the apparent connections between weather patterns and agriculture, this study explores the deeper reasoning behind the integration of these topics. We analyse similarities and differences with other chapters of the Tabṣira and other sources from the Islamicate period to contextualise al-Ashraf ʿUmar’s approach. Notably, the similarities with the winds’ knowledge found in the Ikhwān al-Ṣafāʾ’s Epistles are discussed, although al-Ashraf ʿUmar refuses to fully adopt their philosophical and meteorological frameworks. By considering chapter xxxvi within a cluster of interconnected knowledge, this study aims to deepen our understanding of how pre-modern societies perceived the complex relationships between natural phenomena, cosmological frameworks, and seasonal knowledge. This approach seeks to provide a clearer view of how celestial predictability was linked to terrestrial events, calling for a broader examination of the scientific traditions of the Islamicate world. It highlights the importance of recognising the intertwining of natural, astral, and religious perspectives in shaping the environmental understanding of the past societies. Moreover, the authors provide a new edition and English translation of the chapter to complement this analysis
(書簡)Date: 1996/11/16 ; Sender: Chowdhury, Ashraf Uddin ; Receiver: Tsuru, S (Shigeto)
No full text附:“Proposed Reseach to be Carried Out Under the Japan Foundation Fellowship program1987-88”“RESUME”BUREAU OF ECONOMIC RESEARCH, UNIV. OF DHAKA用紙書簡オリジナルの所在: 一橋大学経済研究所資料室都留重人氏より寄贈1-B1-06-04/00
al-Ashraf ̔Umar’s Tabṣira, Chapter xxiii: Timekeeping at Night by the Moon in 13th-Century Yemen and Beyond
No full textThis article explores methods for determining moonrise and moonset as evidenced within a range of pre-and early modern sources originating from Islamicate societies. The idea emerged during a workshop in July 2022 where a talk by the first author on Ibn Waḥshiyya’s moonrise-moonset text in his al-Filāḥa al-Nabaṭiyya («The book of Nabatean agriculture») and the second author’s project on the Kitāb al-Tabṣira fī ̔ilm alnujūm («Book of enlightenment in the science of the stars») by al-Ashraf ̔Umar revealed overlaps. Given the resemblances observed in the two sources, chapter xxiii of Tabṣira has been selected as the initial reference point for tracing the technique across additional sources. It is important to note that this examination does not assert comprehensiveness, nor does it account for the reciprocal interdependencies among the examples presented. Nevertheless, the present article suggests a categorisation of the diverse methods predicated on various factors such as exactitude, complexity, state of completeness, literary formats, and audience
Automating the determination of wave speed using the pu-loop method
No full textThe PU-loop (pressure-velocity loop) is a method for determining wave speed and relies on the linear relationship between the pressure and velocity in the absence of reflected waves. This linearity of the PU-loop during early systole, which is directly related to wave speed, has always been established by eye. This paper presents a new technique that establishes this linearity and thus determining wave speed online. Pressure and flow were measured in the ascending aorta of 11 anesthetised dogs. The slope of the PU-loop, indicating wave speed was determined by eye and by using the new technique. The difference between the slopes of the two methods is in the order of 3%. The new technique is convenient and allows for the online assessment of wave speed, which could be used as a bedside tool for the assessment of arterial compliance
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