1,516 research outputs found
Micropatterning of bioactive glass nanoparticles on chitosan membranes for spatial controlled biomineralization
[Excerpt] Objectives: Chitosan membranes were patterned with bioactive glass nanoparticles (BG-NPs) capable of bone regeneration by a Microcontact Printing technique, in order to spatially control biomineralization and also cell adhesion and proliferation. [...
V-Shape Liquid Crystal-Based Retromodulator Air to Ground Optical Communications
This paper describes the use of a 2D liquid crystal retro-modulator as a free space, wireless, optical link. The retro-modulator is made up of a retro-reflecting cornercube onto which 2 cascaded V-shape smectics liquid crystal modulators are mounted. The communication link differs with respect to more conventional optical links in not using amplitude (nor frequency) modulation, but instead state-of-polarisation (SOP) modulation known as Polarisation Shift Keying (PolSK). PolSK has the advantage over amplitude modulation, that it is less sensitive to changes in the visibility of the atmosphere, and increases inherently the bandwidth of the link. The implementation of PolSK both in liquid crystal based and in retro-modulated communication are novelties
Shortcuts to adiabaticity in a time-dependent box
A method is proposed to drive an ultrafast non-adiabatic dynamics of an
ultracold gas trapped in a box potential. The resulting state is free from
spurious excitations associated with the breakdown of adiabaticity, and
preserves the quantum correlations of the initial state up to a scaling factor.
The process relies on the existence of an adiabatic invariant and the inversion
of the dynamical self-similar scaling law dictated by it. Its physical
implementation generally requires the use of an auxiliary expulsive potential
analogous to those used in soliton control. The method is extended to a broad
family of many-body systems. As illustrative examples we consider the ultrafast
expansion of a Tonks-Girardeau gas and of Bose-Einstein condensates in
different dimensions, where the method exhibits an excellent robustness against
different regimes of interactions and the features of an experimentally
realizable box potential.Comment: 6 pp, 4 figures, typo in Eq. (6) fixe
Improving adaptive bagging methods for evolving data streams
We propose two new improvements for bagging methods on evolving data streams. Recently, two new variants of Bagging were proposed: ADWIN Bagging and Adaptive-Size Hoeffding Tree (ASHT) Bagging. ASHT Bagging uses trees of different sizes, and ADWIN Bagging uses ADWIN as a change detector to decide when to discard underperforming ensemble members. We improve ADWIN Bagging using Hoeffding Adaptive Trees, trees that can adaptively learn from data streams that change over time. To speed up the time for adapting to change of Adaptive-Size Hoeffding Tree (ASHT) Bagging, we add an error change detector for each classifier. We test our improvements by performing an evaluation study on synthetic and real-world datasets comprising up to ten million examples
Exclusive light particle measurements for the system F + C at 96 MeV
Decay sequence of hot {31}^P nucleus has been investigated through
exclusive light charged particle measurements in coincidence with individual
evaporation residues using the reaction {19}^F (96 MeV) + {12}^C.
Information on the sequential decay chain have been extracted by confronting
the data with the predictions of the statistical model. It is observed from the
present analysis that such exclusive light charged particle data may be used as
a powerful tool to probe the decay sequence of the hot light compound systems.Comment: 13 pages, 8 figures, Physical Review C (in press
diagnostics on the nature of dark energy
The two dominant components of the cosmic budget today, pressureles matter
and dark energy, may or may not be interacting with each other. Currently, both
possibilities appear compatible with observational data. We propose several
criteria based on the history of the Hubble factor that can help discern
whether they are interacting and whether dark energy is phantom or quintessence
in nature.Comment: 22 pages, 7 figures. Accepted for publication in IJMP
Optimally robust shortcuts to population inversion in two-level quantum systems
We examine the stability versus different types of perturbations of recently
proposed shortcuts-to-adiabaticity to speed up the population inversion of a
two-level quantum system. We find optimally robust processes using invariant
based engineering of the Hamiltonian. Amplitude noise and systematic errors
require different optimal protocols.Comment: 17 pages, 7 figure
In situ characterization of main reaction products in alkali-activated slag materials by Confocal Raman Microscopy
The re-use of different aluminosilicates, such as blast furnace slag, in the preparation of alternative binders (alkali-activated materials) to Portland cement materials is well document and evaluated by conventional techniques. The use of XRD, FTIR and TG techniques allows obtaining information about the hydration products formed under the conditions of alkaline activation. The formation of the main reaction product (C-A-S-H gel), due to its low crystallinity, is not easily stablished by XRD or FTIR, and it is also quite complex to obtain quantitative information. Confocal Raman Microscopy (CRM) technique reveals information of each of the present phases during the slag activation and in particular. Moreover, CRM provide the evolution of C-A-S-H gel confirming that the growth of the C-A-S-H gel in activate alkaline-systems is different from that an Ordinary Portland Cement system. C-A-S-H gel grows randomly in the regions rich in calcium and silicon. The use of CRM opens a new possibility for the in situ study of complex systems such as the activation of alkali-activated or geopolymers in the search for alternative materials to Portland cement.This work was supported by the Spanish Ministry of Economy and Competitiveness through the Project MAT-2017-86450-C4-1-R and Spanish National Research Council Project NANOMIND 201560E068. Dr. M. Torres-Carrasco is also indebted to MINECO for a postdoctoral fellowship "Juan de la Cierva-Formación" (ref: FJCI-2016-28488). In addition, O. Mikhailova enjoyed a pre-doctoral fellowship with specific junior project FAST-J-18-5568 from the Brno University of Technology (Czech Republic) for internship in Spain
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