4,572 research outputs found
Governance of Dual-Use Technologies: Theory and Practice
The term dual-use characterizes technologies that can have both military and civilian applications. What is the state of current efforts to control the spread of these powerful technologies—nuclear, biological, cyber—that can simultaneously advance social and economic well-being and also be harnessed for hostile purposes? What have previous efforts to govern, for example, nuclear and biological weapons taught us about the potential for the control of these dual-use technologies? What are the implications for governance when the range of actors who could cause harm with these technologies include not just national governments but also non-state actors like terrorists? These are some of the questions addressed by Governance of Dual-Use Technologies: Theory and Practice, the new publication released today by the Global Nuclear Future Initiative of the American Academy of Arts and Sciences. The publication's editor is Elisa D. Harris, Senior Research Scholar, Center for International Security Studies, University of Maryland School of Public Affairs. Governance of Dual-Use Technologies examines the similarities and differences between the strategies used for the control of nuclear technologies and those proposed for biotechnology and information technology. The publication makes clear the challenges concomitant with dual-use governance. For example, general agreement exists internationally on the need to restrict access to technologies enabling the development of nuclear weapons. However, no similar consensus exists in the bio and information technology domains. The publication also explores the limitations of military measures like deterrence, defense, and reprisal in preventing globally available biological and information technologies from being misused. Some of the other questions explored by the publication include: What types of governance measures for these dual-use technologies have already been adopted? What objectives have those measures sought to achieve? How have the technical characteristics of the technology affected governance prospects? What have been the primary obstacles to effective governance, and what gaps exist in the current governance regime? Are further governance measures feasible? In addition to a preface from Global Nuclear Future Initiative Co-Director Robert Rosner (University of Chicago) and an introduction and conclusion from Elisa Harris, Governance of Dual-Use Technologiesincludes:On the Regulation of Dual-Use Nuclear Technology by James M. Acton (Carnegie Endowment for International Peace)Dual-Use Threats: The Case of Biotechnology by Elisa D. Harris (University of Maryland)Governance of Information Technology and Cyber Weapons by Herbert Lin (Stanford University
On the IMF in a Triggered Star Formation Context
The origin of the stellar initial mass function (IMF) is a fundamental issue
in the theory of star formation. It is generally fit with a composite power
law. Some clues on the progenitors can be found in dense starless cores that
have a core mass function (CMF) with a similar shape. In the low-mass end,
these mass functions increase with mass, albeit the sample may be somewhat
incomplete; in the high-mass end, the mass functions decrease with mass. There
is an offset in the turn-over mass between the two mass distributions. The
stellar mass for the IMF peak is lower than the corresponding core mass for the
CMF peak in the Pipe Nebula by about a factor of three. Smaller offsets are
found between the IMF and the CMFs in other nebulae. We suggest that the offset
is likely induced during a starburst episode of global star formation which is
triggered by the formation of a few O/B stars in the multi-phase media, which
naturally emerged through the onset of thermal instability in the cloud-core
formation process. We consider the scenario that the ignition of a few massive
stars photoionizes the warm medium between the cores, increases the external
pressure, reduces their Bonnor?Ebert mass, and triggers the collapse of some
previously stable cores. We quantitatively reproduce the IMF in the low-mass
end with the assumption of additional rotational fragmentation.Comment: 3 figure
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The role of TMPRSS6/matriptase-2 in iron regulation and anemia
Matriptase-2, encoded by the TMPRSS6 gene, is a member of the type II transmembrane serine protease family. Matriptase-2 has structural and enzymatic similarities to matriptase-1, which has been implicated in cancer progression. Matriptase-2 was later established to be essential in iron homeostasis based on the phenotypes of iron-refractory iron deficiency anemia identified in mouse models as well as in human patients with TMPRSS6 mutations. TMPRSS6 is expressed mainly in the liver and negatively regulates the production of hepcidin, the systemic iron regulatory hormone. This review focuses on the current understanding of matriptase-2 biochemistry, and its role in iron metabolism and cancer progression. In light of recent investigations, the function of matriptase-2 in hepcidin regulation, how it is being regulated, as well as the therapeutic potential of matriptase-2 are also discussed
Automatic Metadata Generation using Associative Networks
In spite of its tremendous value, metadata is generally sparse and
incomplete, thereby hampering the effectiveness of digital information
services. Many of the existing mechanisms for the automated creation of
metadata rely primarily on content analysis which can be costly and
inefficient. The automatic metadata generation system proposed in this article
leverages resource relationships generated from existing metadata as a medium
for propagation from metadata-rich to metadata-poor resources. Because of its
independence from content analysis, it can be applied to a wide variety of
resource media types and is shown to be computationally inexpensive. The
proposed method operates through two distinct phases. Occurrence and
co-occurrence algorithms first generate an associative network of repository
resources leveraging existing repository metadata. Second, using the
associative network as a substrate, metadata associated with metadata-rich
resources is propagated to metadata-poor resources by means of a discrete-form
spreading activation algorithm. This article discusses the general framework
for building associative networks, an algorithm for disseminating metadata
through such networks, and the results of an experiment and validation of the
proposed method using a standard bibliographic dataset
Manual therapy in addition to physiotherapy does not improve clinical or economic outcomes after ankle fracture
Objective: The primary aim of this study was to determine the effectiveness and cost-effectiveness of adding manual therapy to a physiotherapy programme for ankle fracture. Design: Assessor-blinded randomized controlled trial. Participants: Ninety-four adults were recruited within one week of cast removal for isolated ankle fracture. Inclusion criteria were: they were able to weight-bear as tolerated or partial weight-bear, were referred for physiotherapy, and experienced pain. Ninety-one participants completed the study. Methods: Participants were randomly allocated to receive manual therapy (anterior-posterior joint mobilization over the talus) plus a standard physiotherapy programme (experimental), or the standard physiotherapy programme only (control). They were assessed by a blinded assessor at baseline, and at 4, 12 and 24 weeks. The main outcomes were activity limitation and quality of life. Information on costs and healthcare utilization was collected every 4 weeks up to 24 weeks. Results: There were no clinically worthwhile differences in activity limitation or quality of life between groups at any time-point. There was also no between-group difference in quality-adjusted life-years, but the experimental group incurred higher out-of-pocket costs (mean between-group difference = AU$200, 95% confidence interval 26-432). Conclusion: When provided in addition to a physiotherapy programme, manual therapy did not enhance outcome in adults after ankle fracture. © 2008 Foundation of Rehabilitation Information
Stabilization of Hydrodynamic Flows by Small Viscosity Variations
Motivated by the large effect of turbulent drag reduction by minute
concentrations of polymers we study the effects of a weakly space-dependent
viscosity on the stability of hydrodynamic flows. In a recent Letter [Phys.
Rev. Lett. {\bf 87}, 174501, (2001)] we exposed the crucial role played by a
localized region where the energy of fluctuations is produced by interactions
with the mean flow (the "critical layer"). We showed that a layer of weakly
space-dependent viscosity placed near the critical layer can have a very large
stabilizing effect on hydrodynamic fluctuations, retarding significantly the
onset of turbulence. In this paper we extend these observation in two
directions: first we show that the strong stabilization of the primary
instability is also obtained when the viscosity profile is realistic (inferred
from simulations of turbulent flows with a small concentration of polymers).
Second, we analyze the secondary instability (around the time-dependent primary
instability) and find similar strong stabilization. Since the secondary
instability develops around a time-dependent solution and is three-dimensional,
this brings us closer to the turbulent case. We reiterate that the large effect
is {\em not} due to a modified dissipation (as is assumed in some theories of
drag reduction), but due to reduced energy intake from the mean flow to the
fluctuations. We propose that similar physics act in turbulent drag reduction.Comment: 10 pages, 17 figs., REVTeX4, PRE, submitte
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