511 research outputs found
An Efficient and Robust Method for Lagrangian Magnetic Particle Tracking in Fluid Flow Simulations on Unstructured Grids
No full textIn this paper we report on a newly developed particle tracking scheme for fluid flow simulations on 3D unstructured grids, aiming to provide detailed insights in the particle behaviour in complex geometries. A possible field of applications is the Magnetic Drug Targeting (MDT) technique, on which this paper will be focused. MDT is a promising medical technique that uses locally applied magnetic fields to capture magnetic drug carriers at the desired locations in the human body, strongly increasing the efficiency of medical drugs. The new particle tracking scheme combines the advantages of existing methods and is easy for implementation in a generic numerical code. The scheme is tested and validated for simple MDT cases that include effects of a non-homogeneous magnetic field on deposition of magnetic particles in laminar flow. The first test case is a validation study of the magnetic particle trajectories released in a horizontal circular pipe flow with a current-carrying wire parallel to the flow, for which analytical solutions are reported in literature. The second test case involves particle capture efficiencies in a 90o bent tube for different configurations of the imposed magnetic field. This configuration corresponds more closely to the conditions inside blood vessels, because of the presence of secondary motions. These results are compared with numerical studies from literature too. The obtained results demonstrate that the developed particle tracking scheme is a very robust, efficient and accurate method, which can give detailed insights in particle behaviour in complex geometries. As such it is a good candidate for future applications and optimisations of MDT technique for loco-regional cancer treatment or treatment of cardiovascular diseases.Multi-Scale PhysicsApplied Science
#413 The H-Bomb and the Future.
No full textParticipants include: Mr. James R. Shepley, Co-Author of The Hydrogen Bomb Mr. Clay Blair Jr., Co-Author of Mr. Ramsay D. Potts, Former Administrative Asst. to Senator Stuart Symington; Author of articles on Military and Policy Implications of Atomic Weapons Developmen
Epigrafía maya: Tabasco
No full textLa información de esta miniguía está basada en los trabajos de M. Coe, N. Grove, S. Guenter, S. Martín, P. Mathews, Linda Schele, D. Stuart y M. U. Zender.Cuatro de las grandes culturas desarrolladas en Mesoamérica poseían un sistema propio de escritura: zapoteca, maya, mixteca y náhuatl. La escritura maya fue el sistema más complejo y el que más correspondencia tuvo con la lengua hablada. Parece haber surgido alrededor del 100 o 200 d.C., y según la mitología fue el dios ltzamná quien la inventó. Sus últimas expresiones se sitúan alrededor de 1696. Los mayas utilizaron diferentes soportes para plasmar la escritura y su historia escrita, como códices de papel vasijas de barro, textiles, pieles, estelas y altares de piedra, dinteles y cajas de madera, pendientes de hueso y hasta finas puntas de cola de mantarraya, entre otros.</p
Social simulation comparison in arbitrary problem domains: first steps towards a more principled approach
No full textWe outline a simulation development process, backed by a software framework, which focuses on developing and using a partial conceptual model as a ‘lens’ to compare and possibly re-implement existing models in a chosen problem domain (as well as to design new models). To make this feasible for existing models of arbitrary structure and background social theory, we construct our (partial) conceptual model in a way that acknowledges that it is a base representation which any individual model will typically add detail to, and abstract away from, in various ways which we argue can be formalised. A given model’s design is fitted to the conceptual model to capture how its structural architecture (and selected aspects of the system’s state and driving processes) map to the conceptual model. This fit can be used to produce incomplete skeleton code which can then be extended to produce a simulation. Along the way, we discuss how the field of robust decision-making provides a useful context for this, and how it differs from other approaches. This is inevitably a preliminary approach to a broad and difficult problem, so we end by discussing some of the main issues and what might be needed next
More Employers, More Jobs, More Money: An Empirical Analysis of Local Economic Development Policy Impacts in U.S. Cities
No full textLocal government leaders in the U.S. employ a multitude of programs and policies in the name of economic development to increase the number of firms, employment, wages, and, of course, the tax base. The past few decades have seen a surge in local economic development policies, yet research analyzing their effectiveness is sparse. This study analyzes the relationship between local economic development policy and economic growth in a data set of 412 U.S. cities. Results indicate that policy has only has a weak correlation with economic growth, suggesting that growth is determined more by market conditions rather than government intervention. The article concludes with an entrepreneurial policy approach this author believes may yield development results in an era of limited policy effectiveness.Economic development, Cities, Attraction, Retention, Incentives
Combining the production and the valorization of academic research: A qualitative investigation of enacted mechanisms.
No full textThe emergence of knowledge-based societies over the past decades has spurred research on the specific role of universities in innovation systems. The notion of academic entrepreneurship has gained acceptance among communities of researchers, practitioners and policy makers (Etzkowitz et al., 1998). At the same time, this acceptance seems impregnated by a constant alertness for the tensions that may arise. Concerns are uttered about shifts of the academic research agenda towards industry needs, resulting in fewer investments in basic research. Furthermore, the conflicting nature of the normative principles that guide academia and business has been warned for: competitive considerations and secrecy practices would stand in direct opposition to the principle of free dissemination of scientific knowledge (Dasgupta and David, 1987; Florida and Cohen, 1999; Geuna, 1999; Noble, 1977).Agency; Applicant; Assignee; Assignment; Business; Companies; Country; Data; EPO; Indicators; Information; Innovation; Institutional; Inventors; Methods; Order; Patent; Patent statistics; Patentee; Performance; Policy; Regions; Research; Researchers; Sector; Sector assignment; Technology; Time; University; USPTO; Innovation systems; Systems; Academic entrepreneurship; Community; Research agenda; Industry; Industries; Investments; Investment; Basic research; Principles; Dissemination; Knowledge;
The structure of Herpesvirus Fusion Glycoprotein B-Bilayer Complex reveals the protein-membrane and lateral protein-protein interaction
No full textGlycoprotein B (gB) is a key component of the complex herpesvirus fusion machinery. We studied membrane interaction of two gB ectodomain forms and present an electron cryotomography structure of the gB-bilayer complex. The two forms differed in presence or absence of the membrane proximal region (MPR) but showed an overall similar trimeric shape. The presence of the MPR impeded interaction with liposomes. In contrast, the MPR-lacking form interacted efficiently with liposomes. Lateral interaction resulted in coat formation on the membranes. The structure revealed that interaction of gB with membranes was mediated by the fusion loops and limited to the outer membrane leaflet. The observed intrinsic propensity of gB to cluster on membranes indicates an additional role of gB in driving the fusion process forward beyond the transient fusion pore opening and subsequently leading to fusion pore expansion
Policy research on migration and development
No full textThis is a survey and analysis-with commentary-of migration issues and the related development policies for the sending countries."Migration and development"is considered an unsettled and unresolved area for good reason. The policy issues are surprisingly deep and run to basic issues such as the nature of development as opposed to simple poverty reduction. North-north migration (between industrial countries), south-south migration (between or within developing countries), and north-south migration (from developing to industrial countries) are all covered although the paper focuses on the north-south variety. Attention is paid to the question of the dynamic mechanism underlying migration being one of convergence or divergence. Very often the policy issues push one outside what would be narrowly considered as"migration studies."For example, policies to reduce the brain drain go directly to the issue of educational reform in developing countries while policies to increase the developmental impact of remittances quickly carry one into the nature of business development itself. Ronald Dore's ideas on educational reform are outlined as a policy approach to the brain drain problem. Jane Jacobs'ideas on development are outlined in greater length as they are little known in development economics and yet directly address the policy issues raised by migration and development.Banks&Banking Reform,Health Monitoring&Evaluation,Human Migrations&Resettlements,Voluntary and Involuntary Resettlement,Public Health Promotion,Health Monitoring&Evaluation,Banks&Banking Reform,Human Migrations&Resettlements,Voluntary and Involuntary Resettlement,Municipal Financial Management
Renegotiating the Food Aid Convention: Background, context, and issues
No full text"The current global agreement governing food aid—the Food Aid Convention (FAC)—will expire in 2007. It has come under heavy criticism as has the diffuse set of broader food aid governance institutions that has emerged in the last 50 years. These institutions are characterized by overlapping mandates, differing degrees of authority and legitimacy, varied levels of transparency in decisionmaking, and problematic representation of the major stakeholders. A number of issues are likely to arise during the course of negotiations over a new FAC. These include its objectives; the nature of commitments—whether to express them in tonnage, value, or nutritional terms; the level of commitments and their distribution among donor countries; monitoring and enforcement of commitments; representation on the FAC governing body among food aid donor- and recipient-country governments and civil society organizations; and the institutional “home” of the FAC. More specifically, there is debate over such questions as whether the new FAC should have an “instrument focus”—food aid—or a “problem focus” such as “food security” or “hunger.” If the focus is on addressing hunger, should food aid under the FAC be restricted to emergencies only or should it pertain to broader food security issues? Should the FAC be a low-key forum for exchange of information or should it have some meaningful ways of monitoring commitments and encouraging compliance by both donors and recipients? Debates such as these will reflect views on the purposes of food aid itself. Conversely, debates regarding these broader questions carry consequences for the formation of views on the issues involved in the FAC negotiations. This paper's purpose is solely to outline issues and options; hence it does not advocate for particular positions." Authors' AbstractFood aid, International agreements, International organizations, Humanitarian assistance, Human rights, Local purchase, Triangular transaction, Development assistance, Trade agreements, Grain trade, Code of conduct, Needs assessment,
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