169 research outputs found
Participatory Demand-supply Systems
AbstractIntroducing the notion of Participatory Demand-Supply (PDS) systems as socio-technical systems, this paper focuses on a new approach to coordinating demand and supply in dynamic environments. A participatory approach to demand and supply provides a new frame of reference for system design, for which the engagement of all stakeholders plays an important role, as does distributed ICT. This approach has been applied to an industrial case to explore new opportunities enabled by distributed ICT for communication, negotiation, joint decision-making, and collective learning required for coordinating demand and supply. The application results in a platform as a test-bed for collecting relevant information to study the participation of stakeholders (actors) in coordinating a PDS system
Collaboration entre recherche académique et industrie dans l'étude d'un nouveau médicament anti-ostéoporotique
L'activité de l'ostéoclaste, cellule en charge de la résorption osseuse, est soumise à différents facteurs de régulation. Parmi eux, ceux issus de la matrice, en particulier les minéraux qui en sont libérés, comme le calcium, sont déterminants. Nous avons montré que la variation de concentration en calcium dans le milieu régulait l'activité de résorption et la durée de vie des ostéoclastes. Le développement d'une nouvelle thérapeutique, le ranélate de strontium, a montré des effets cliniques très intéressants reposant sur une stimulation des activités de formation de l'os par les ostéoblastes et une modulation des activités de résorption osseuse. Sur la base de nos connaissances de la physiologie de l'ostéoclaste, en particulier des voies de signalisation calcique, et de la maîtrise de différents modèles cellulaires ostéoclastiques, une collaboration logique s'est créée entre notre laboratoire et Servier afin d'approfondir les mécanismes à l'origine des effets du ranélate de strontium sur les ostéoclastes. En quelques années, cette collaboration s'est progressivement enrichie d'autres intervenants scientifiques afin de mieux éclairer ces mécanismes. Il a ainsi été montré que le strontium interagissait probablement avec le récepteur sensible au calcium et que les voies de signalisation intracellulaires activées par le calcium et le ranélate de strontium via ce récepteur étaient différentes. Dans le cadre de cette coopération avec Servier, des échanges avec d'autres laboratoires universitaires ont été initiés, telles que la mise en commun de techniques et de connaissances. Ainsi, il a été possible de confirmer la présence du récepteur sensible au calcium sur les ostéoclastes et de montrer son rôle dans les effets du ranélate de strontium sur l'ostéoclaste.The activity of the osteoclast, the cell responsible for bone resorption, is subjected to different regulation factors. Amongst these, those issued from the matrix, particularly released minerals such as calcium, are determinants. We have shown that variations in calcium concentration in the medium regulates resorption activity and duration of the osteoclast lifespan. The development of a new therapeutic agent, strontium ranelate, has shown very interesting clinical effects reliant on the stimulation of bone formation activity by osteoblasts and modulation of bone resorption activity. From our knowledge regarding osteoclast physiology, in particular calcium signaling pathways, and the control of different osteoclast cellular models, a consequent collaboration was formed between our laboratory and Servier in order to elaborate on the effects of strontium ranelate on the osteoclast. In several years, this collaboration has been further enriched by other collaborators in order to better understand this mechanism. It has also been shown that strontium likely interacts with the calcium-sensing receptor and that the pathways of intracellular signaling pathways activated by calcium and strontium ranelate via this receptor are different. In fact, within the scope of this collaboration with Servier, exchanges with other academic laboratories were initiated and collaboration on numerous techniques became possible. Then, it has been possible to confirm the presence of the calcium-sensing receptor on the osteoclasts and to demonstrate its role in the molecular events associated with strontium ranelate's effects on the osteoclast
Erratum: Vascular calcification in patients with type 2 diabetes: the involvement of matrix Gla protein
A Framework for Developing Agent-Based Distributed Applications
Abstract—The development of large-scale distributed multiagent systems in open dynamic environments is a challenge. System behavior is often not predictable and can only be evaluated by execution. This paper proposes a framework to support design and development of such systems: a framework in which both simulation and emulation play an important role. A distributed agent platform (AgentScape) is used to illustrate the potential of the framework. Keywords-multi-agent systems, agent-based simulation, emulation, development, distributed systems I
The Identification of the X-ray Counterpart to PSR J2021+4026
We report the probable identification of the X-ray counterpart to the
gamma-ray pulsar PSR J2021+4026 using imaging with the Chandra X-ray
Observatory ACIS and timing analysis with the Fermi satellite. Given the
statistical and systematic errors, the positions determined by both satellites
are coincident. The X-ray source position is R.A. 20h21m30.733s, Decl. +40 deg
26 min 46.04sec (J2000) with an estimated uncertainty of 1.3 arsec combined
statistical and systematic error. Moreover, both the X-ray to gamma-ray and the
X-ray to optical flux ratios are sensible assuming a neutron star origin for
the X-ray flux. The X-ray source has no cataloged infrared-to-visible
counterpart and, through new observations, we set upper limits to its optical
emission of i' >23.0 mag and r' > 25.2mag. The source exhibits an X-ray
spectrum with most likely both a powerlaw and a thermal component. We also
report on the X-ray and visible light properties of the 43 other sources
detected in our Chandra observation.Comment: Accepted for publication in the Astrophysical Journa
Monopolar Pulsar Spin-Down
A multipole spin-down equation based on a monopolar term is derived from the
general expression and used to study pulsar evolution.
We show that the time-independent version of such equation cannot reproduce the
observed properties of pulsars and conclude that there is no equation of the
form consistent with the \pp diagram and braking index
measurements. We explore the time-dependent model under the hypothesis of
decaying magnetic fields, showing that an inverse linear decay gives reasonable
evolutionary trajectories. This model distinguishes the evolution of Vela from
that of the other three young pulsars considered. We discuss the origin of the
monopolar term, which cannot be attributed to radiative processes, pointing to
the importance of particle acceleration and/or mass loss processes in the
dynamical evolution of pulsars.Comment: 9 pages, accepted for publication in the Astronomy and Astrophysics
Journa
Experience-based utility and own health state valuation for a health state classification system: why do it and how to do it
In the estimation of population value sets for health state classification systems such as the EQ-5D,
there is increasing interest in asking respondents to value their own health state, sometimes referred to as "experienced-based utility values" or more correctly ownrather than hypothetical health states. Own health
state values differ to hypothetical health state values, and this may be attributed to many reasons. This paper
critically examines: whose values matter; why there is a difference between own and hypothetical values; how
to measure own health state values; and why to use own health state values. Finally, the paper also examines
other ways that own health state values can be taken into account, such as including the use of informed general
population preferences that may better take into account experience-based values
Chandra imaging of the X-ray nebula powered by pulsar B1509-58
We present observations with the Chandra X-ray Observatory of the pulsar wind
nebula (PWN) powered by the energetic young pulsar B1509-58. These data confirm
the complicated morphology of the system indicated by previous observations,
and in addition reveal several new components to the nebula. The overall PWN
shows a clear symmetry axis oriented at a position angle 150 degrees (N through
E), which we argue corresponds to the pulsar spin axis. We show that a
previously identified radio feature matches well with the overall extent of the
X-ray PWN, and propose the former as the long-sought radio nebula powered by
the pulsar. We further identify a bright collimated feature, at least 4' long,
lying along the nebula's main symmetry axis; we interpret this feature as a
physical outflow from the pulsar, and infer a velocity for this jet >0.2c. The
lack of any observed counter-jet implies that the pulsar spin axis is inclined
at approx 30 deg to the line-of-sight, contrary to previous estimates made from
lower-resolution data. We also identify a variety of compact features close to
the pulsar. A pair of semi-circular X-ray arcs lie 17 and 30 arcsec to the
north of the pulsar; the latter arc shows a highly-polarized radio counterpart.
We show that these features can be interpreted as ion-compression wisps in a
particle-dominated equatorial flow, and use their properties to infer a ratio
of electromagnetic to particle energy in pairs at the wind shock sigma approx
0.005, similar to that seen in the Crab Nebula. We further identify several
compact knots seen very close to the pulsar; we use these to infer sigma <
0.003 at a separation from the pulsar of 0.1 pc.Comment: 22 pages, including 9 embedded EPS figures, uses emulateapj. Now
incorporates referee's comments - no major changes. To appear in The
Astrophysical Journal, vol 569 (2002 April 20
Diverse Temperate Bacteriophage Carriage in Clostridium difficile 027 Strains
The hypervirulent Clostridium difficile ribotype 027 can be classified into subtypes, but it unknown if these differ in terms of severity of C. difficile infection (CDI). Genomic studies of C. difficile 027 strains have established that they are rich in mobile genetic elements including prophages. This study combined physiological studies, electron microscopy analysis and molecular biology to determine the potential role of temperate bacteriophages in disease and diversity of C. difficile 027.We induced prophages from 91 clinical C. difficile 027 isolates and used transmission electron microscopy and pulsed-field gel electrophoresis to characterise the bacteriophages present. We established a correlation between phage morphology and subtype. Morphologically distinct tailed bacteriophages belonging to Myoviridae and Siphoviridae were identified in 63 and three isolates, respectively. Dual phage carriage was observed in four isolates. In addition, there were inducible phage tail-like particles (PT-LPs) in all isolates. The capacity of two antibiotics mitomycin C and norfloxacin to induce prophages was compared and it was shown that they induced specific prophages from C. difficile isolates. A PCR assay targeting the capsid gene of the myoviruses was designed to examine molecular diversity of C. difficile myoviruses. Phylogenetic analysis of the capsid gene sequences from eight ribotypes showed that all sequences found in the ribotype 027 isolates were identical and distinct from other C. difficile ribotypes and other bacteria species.A diverse set of temperate bacteriophages are associated with C. difficile 027. The observed correlation between phage carriage and the subtypes suggests that temperate bacteriophages contribute to the diversity of C. difficile 027 and may play a role in severity of disease associated with this ribotype. The capsid gene can be used as a tool to identify C. difficile myoviruses present within bacterial genomes
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