1,361 research outputs found
Separate measurement- and feedback-driven entanglement transitions in the stochastic control of chaos
We study measurement-induced entanglement and control phase transitions in a
quantum analog of the Bernoulli map subjected to a classically-inspired control
protocol. When entangling gates are restricted to the Clifford group, separate
entanglement () and control () transitions
emerge, revealing two distinct universality classes. The control transition has
critical exponents and consistent with the classical map (a random
walk) while the entanglement transition is revealed to have similar exponents
as the measurement-induced phase transition in Clifford hybrid dynamics. This
is distinct from the case of generic entangling gates in the same model, where
and universality is controlled by the random
walk.Comment: 6 + 1 pages, 4 + 1 figure
Compact FTICR Mass Spectrometry for Real Time Monitoring of Volatile Organic Compounds
International audienceIn this paper, we present a compact Fourier transform ion cyclotron resonance mass spectrometer (FTICR-MS) designed for real time analysis of volatile organic compounds (VOCs) in air or in water. The spectrometer is based on a structured permanent magnet made with NdFeB segments. Chemical ionization is implemented inside the ICR cell. The most widely used reaction is the proton transfer reaction using H 3 O + precursor ions, but other ionic precursors can be used to extend the range of species that can be detected. Complex mixtures are studied by switching automatically from one precursor to another. The accuracy obtained on the mass to charge ratio (∆m/z 5 × 10 −3), allows a precise identification of the VOCs present and the limit of detection is 200 ppb without accumulation. The time resolution is a few seconds, mainly limited by the time necessary to come back to background pressure after the gas pulses. The real time measurement will be illustrated by the monitoring of VOCs produced during the thermal degradation of a polymer and by an example where three different precursor ions are used alternatively to monitor a gas sample
Temperature dependent characterization of optical fibres for distributed temperature sensing in hot geothermal wells
This study was performed in order to select a proper fibre for the
application of a distributed temperature sensing system within a hot geothermal
well in Iceland. Commercially available high temperature graded index fibres
have been tested under in-situ temperature conditions. Experiments have been
performed with four different polyimide coated fibres, a fibre with an aluminum
coating and a fibre with a gold coating. To select a fibre, the relationship
between attenuation, temperature, and time has been analyzed together with SEM
micrographs. On the basis of these experiments, polyimide fibres have been
chosen for utilisation. Further tests in ambient and inert atmosphere have been
conducted with two polyimide coated fibres to set an operating temperature
limit for these fibres. SEM micrographs, together with coating colour changes
have been used to characterize the high temperature performance of the fibres.
A novel cable design has been developed, a deployment strategy has been worked
out and a suitable well for deployment has been selected.Comment: PACS: 42.81.Pa, 93.85.Fg, 47.80.Fg, 91.35.Dc, 07.20.Dt, 07.60.V
Formulation of composite resistive pastes for micro-heater manufacturing
We investigate in this work the formulation of composite resistive pastes based on epoxy resins and graphite for micro-heater manufacturing via thick-film technology. The resistive paste is first screen-printed onto a printed circuit board (PCB) substrate, and then coated with expandable polydimethylsiloxane (PDMS), a composite based on an elastomeric matrix and expandable microspheres, resulting into one-shot thermal actuators allowing pumping and sealing in microfluidic devices. The resistive paste must therefore have controlled properties, such as rheology, resistivity and temperature stability. This paper details the formulation and characterization of suitable epoxy-graphite resistive composites, and the control of their properties through additive
Formulation of composite resistive pastes for fabrication of micro-heaters
We investigate in this work the formulation of composite resistive pastes based on epoxy resins and graphite for micro-heater manufacturing via thick-film technology. These resistive pastes are designed for screen-printing onto a printed circuit board (PCB) substrate; further coating with expandable polydimethylsiloxane (PDMS), a composite based on an elastomeric matrix and expandable microspheres, results in one-shot thermal actuators allowing pumping and sealing in disposable micro-fluidic lab-on-a-chip devices. The resistive paste must therefore have controlled rheology and resistivity, and exhibit good temperature stability in order to allow high heating power densities. This paper details the formulation and characterisation of suitable epoxy–graphite resistive composites, and the control of their properties through solvents
Spatio-temporal structure of cell distribution in cortical Bone Multicellular Units: a mathematical model
Bone remodelling maintains the functionality of skeletal tissue by locally
coordinating bone-resorbing cells (osteoclasts) and bone-forming cells
(osteoblasts) in the form of Bone Multicellular Units (BMUs). Understanding the
emergence of such structured units out of the complex network of biochemical
interactions between bone cells is essential to extend our fundamental
knowledge of normal bone physiology and its disorders. To this end, we propose
a spatio-temporal continuum model that integrates some of the most important
interaction pathways currently known to exist between cells of the osteoblastic
and osteoclastic lineage. This mathematical model allows us to test the
significance and completeness of these pathways based on their ability to
reproduce the spatio-temporal dynamics of individual BMUs. We show that under
suitable conditions, the experimentally-observed structured cell distribution
of cortical BMUs is retrieved. The proposed model admits travelling-wave-like
solutions for the cell densities with tightly organised profiles, corresponding
to the progression of a single remodelling BMU. The shapes of these spatial
profiles within the travelling structure can be linked to the intrinsic
parameters of the model such as differentiation and apoptosis rates for bone
cells. In addition to the cell distribution, the spatial distribution of
regulatory factors can also be calculated. This provides new insights on how
different regulatory factors exert their action on bone cells leading to
cellular spatial and temporal segregation, and functional coordination.Comment: 14 pages, 5 figures; v2: Completed model description after Eq. (16),
clarified discussion/description after Eq. (23), between Eqs. (29)-(31), and
in 2nd bullet point in conclusion
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