340 research outputs found
understanding and control of ultrsfast currents for terahertz generation
No full textDevelopment of terahertz pulse sources and methods are ongoing with an urge to reduce cost, increase quality of emitter design and improve on the output power. This thesis details two advances made in creating terahertz pulses from ultrafast currents, the first is optimising the biasing method used on photoconductive antennas for terahertz emission and the second manufacturing and studying electronemission type terahertz emitters.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Terahertz-pulse emission through excitation of surface plasmons in metallic nanostructures
No full textA Unicore Globus Interoperability Layer
No full textFor several years, UNICORE and Globus have co-existed as approaches to exploiting what has become known as the "Grid". Both offer many services beneficial for creating and using production Grids. A cooperative approach, providing interoperability between Globus and UNICORE, would result in an advanced set of Grid services that gain strength from each other. This paper outlines some of these parallels and differences as they relate to the development of an interoperability layer between UNICORE and Globus. Given the increasing ubiquity of Globus, what emerges is the desire for a hybridised facility that utilises the UNICORE work-flow management of complex, multi-site tasks, but that can run on either UNICORE- or Globus-enabled resources. The technical challenge in achieving this, addressed in this paper, consists of mapping resource descriptions from both grid environments to an abstract format appropriate to work-flow preparation, and then the instantiation of work-flow tasks on the target systems. Other issues such as reconciling disparate security models and file transfer support are also addressed
A geographic survey of silver concentrations in the gastropod, Tegula funebralis (A. Adams, 1855)
No full textby Author Russell FlegalA thesis prsented to the faculty of Moss Landing Marine Laboratories.Thesis (M.S.) -- California State University, Hayward, 1976."A thesis presented to the faculty of Moss Landing Marine Laboratories.
Terahertz emission from nano-structured metal surfaces
No full textNanostructured metal surfaces were created by depositing a 30 nm layer of bulk gold onto a periodic fused silica transmission grating. By exciting this with a femtosecond laser beam, in air, results in terahertz radiation being produced. This emission is angle dependent. Furthermore, the emitted radiation has a third order power dependence ruling out the chi((2)) process, optical rectification
Neuropsychological constraints to human data production on a global scale
No full textWhich are the factors underlying human information production on a global level? In order to gain an insight into this question we study a corpus of 252–633 mil. publicly available data files on the Internet corresponding to an overall storage volume of 284–675 Terabytes. Analyzing the file size distribution for several distinct data types we find indications that the neuropsychological capacity of the human brain to process and record information may constitute the dominant limiting factor for the overall growth of globally stored information, with real-world economic constraints having only a negligible influence. This supposition draws support from the observation that the files size distributions follow a power law for data without a time component, like images, and a log-normal distribution for multimedia files, for which time is a defining qualia.
Author summary: The generation of new information is limited by two key factors, by the incurring economic costs and by the capacity of the human brain to process and store data and information; the controlling agent needs to retain an overall understanding even when data is generated by semiautomatic processes. These processes are reflected in the statistical properties of the data files publicly available on the Internet. Collecting a corpus of 252–633 mil. files we find that the statistics of the file size distribution are consistent with the supposition that data production on a global level is shaped and limited by the neuropsychological information processing capacity of the brain, with economic and hardware constraints having a negligible influence
History of Genetics
No full textIt takes an unusual person to write a really good history of any branch of science. Professor A. H. Sturtevant, the author of A History of Genetics (Harper and Row, New York, 1965. 165 pp., $5.50), is indeed such a person . He has been an active and creative geneticist for more than half
a century, and has known personally most of those who have worked significantly in modern genetics in the period from the rediscovery and confirmation of Gregor Mendel's work in
1900 to the end of the 50-year time span covered by his book
Truth in Renaissance Historiography : The Case of Johannes Magnus
No full textThe 19th century rise of history as an academic discipline set new standards for acceptable methods of writing history. This greatly influenced the opinions historians held of older historical works, such as the Historia de omnibus Gothorum Sueonumque regibus (History of all the Kings of the Goths and the Swedes) by the Swedish archbishop Johannes Magnus (1488-1544). The work has been criticised for the absence of a proper critical approach to sources and for its lack of truthfulness. Johannes Magnus’ work is still regarded with a degree of suspicion in this respect. Paradoxically, the very definition of the word historian in the Renaissance was an author who dealt with true things, and Johannes Magnus himself writes that his work was characterized by truth. This statement indicates that his notion of historical truth (as well as that of his contemporaries) was different from that of later historians. This article proposes a way of approaching Johannes Magnus’ notion of historical truth by comparing his version of an event with that of his source and discussing the differences
The Contributions of Professor Amartya Sen in the Field of Human Rights
No full textThis paper analyses the work of the Nobel Prize winning economist Professor Amartya Sen from the perspective of human rights. It assesses the ways in which Sen's research agenda has deepened and expanded human rights discourse in the disciplines of ethics and economics, and examines how his work has promoted cross-fertilisation and integration on this subject across traditional disciplinary divides. The paper suggests that Sen's development of a 'scholarly bridge' between human rights and economics is an important and innovative contribution that has methodological as well as substantive importance and that provides a prototype and stimuli for future research. It also establishes that the idea of fundamental freedoms and human rights is itself an important gateway into understanding the nature, scope and significance of Sen's research. The paper concludes with a brief assessment of the challenges to be addressed in taking Sen's contributions in the field of human rights forward.Amartya Sen, human rights, poverty, freedom, obligation, capability approach, meta-rights, entitlements, opportunity freedom, liberty-rights
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