17,673 research outputs found
Finitely generated ideal languages and synchronizing automata
We study representations of ideal languages by means of strongly connected
synchronizing automata. For every finitely generated ideal language L we
construct such an automaton with at most 2^n states, where n is the maximal
length of words in L. Our constructions are based on the De Bruijn graph.Comment: Submitted to WORDS 201
Avaliação de plantas da família Rubiaceae existentes no horto de plantas medicinais da Embrapa Amazônia Oriental.
Wetspun poly-L-(lactic acid)-borosilicate bioactive glass scaffolds for guided bone regeneration
We developed a porous poly-L-lactic acid (PLLA) scaffold compounded with borosilicate bioactive glasses (BBGs) endowing it with bioactive properties. Porous PLLA-BBG fibre mesh scaffolds were successfully prepared by the combination of wet spinning and fibre bonding techniques. Micro-computed tomography (μCT) confirmed that the PLLA-BBG scaffolds containing ≈ 25% of BBGs (w/w) exhibited randomly interconnected porous (58 to 62% of interconnectivity and 53 to 67% of porosity) with mean pore diameters higher that 100 μm. Bioactivity and degradation studies were performed by immersing the scaffolds in simulated body fluid (SBF) and ultrapure water, respectively. The PLLA-BBG scaffolds presented a faster degradation rate with a constant release of inorganic species, which are capable to produce calcium phosphate structures at the surface of the material after 7 days of immersion in SBF (Ca/P ratio of ~ 1.7). Cellular in vitro studies with human osteosarcoma cell line (Saos-2) and human adipose-derived stem cells (hASCs) showed that PLLA-BBGs are not cytotoxic to cells, while demonstrating their capacity to promote cell adhesion and proliferation. Overall, we showed that the proposed scaffolds present a tailored kinetics on the release of inorganic species and controlled biological response under conditions that mimic the bone physiological environment.JSF acknowledges the Portuguese Foundation for Science and Technology (FCT) for his PhD grant BD/73162/2010. This work was partially supported by the European Research Council grant agreement ERC-2012-ADG20120216-321266 - project ComplexiTE
Study on the perception of DIY in domotics in Portugal
The growth of the home automation market depends on technological innovations, rapid evolution of the Internet of Things and Do-It-Yourself (DIY) solutions. This project analysed the perception about domotics related to DIY in Portugal, intending to understand if smart home technologies are used and valued, which factors motivate their acquisition, their purpose and the advantages perceived by users. A questionnaire was used to collect data, resulting in an exploratory study based on data from a convenience sample. The model to evaluate this study was based on the constructs based on Technology Acceptance Models - TAM. From the results obtained, it was concluded that the respondents have a positive perception about domotics and its usefulness faced with DIY on the technologies that make a smart home. Regarding the acquisition and installation of technologies associated with home automation on their own, the respondents are divided, as half consider that they can do it autonomously and the other half only with the intervention of specialists in home automation
Biomimetic strategies to engineer mineralised human tissues
In the last few years, many reports have been describing promising biocompatible and biodegradable materials that can mimic in a certain extent the multidimensional hierarchical structure of bone, while are also capable of releasing bioactive agents or drugs in a controlled manner. Despite these great advances, new developments in the design and fabrication technologies are required to address the need to engineer suitable biomimetic materials in order tune cells functions, i.e. enhance cell-biomaterial interactions, and promote cell adhesion, proliferation, and differentiation ability. Scaffolds, hydrogels, fibres and composite materials are the most commonly used as biomimetics for bone tissue engineering. Dynamic systems such as bioreactors have also been attracting great deal of attention as it allows developing a wide range of novel in vitro strategies for the homogeneous coating of scaffolds and prosthesis with ceramics, and production of biomimetic constructs, prior its implantation in the body. Herein, it is overviewed the biomimetic strategies for bone tissue engineering, recent developments and future trends. Conventional and more recent processing methodologies are also described
On the determination of the spin of the black hole in Cyg X-1 from X-ray reflection spectra
The spin of Cygnus X-1 is measured by fitting reflection models to Suzaku
data covering the energy band 0.9-400 keV. The inner radius of the accretion
disc is found to lie within 2 gravitational radii (r_g=GM/c^2) and a value for
the dimensionless black hole spin is obtained of 0.97^{+0.014}_{-0.02}. This
agrees with recent measurements using the continuum fitting method by Gou et
al. and of the broad iron line by Duro et al. The disc inclination is measured
at 23.7^{+6.7}_{-5.4} deg, which is consistent with the recent optical
measurement of the binary system inclination by Orosz et al of 27+/-0.8 deg. We
pay special attention to the emissivity profile caused by irradiation of the
inner disc by the hard power-law source. The X-ray observations and simulations
show that the index q of that profile deviates from the commonly used,
Newtonian, value of 3 within 3r_g, steepening considerably within 2r_g, as
expected in the strong gravity regime.Comment: 7 pages, 10 figures, MNRAS in pres
Influence of the external pressure on the quantum correlations of molecular magnets
The study of quantum correlations in solid state systems is a large avenue
for research and their detection and manipulation are an actual challenge to
overcome. In this context, we show by using first-principles calculations on
the prototype material KNaCuSiO that the degree of quantum
correlations in this spin cluster system can be managed by external hydrostatic
pressure. Our results open the doors for research in detection and manipulation
of quantum correlations in magnetic systems with promising applications in
quantum information science
Writing electronic ferromagnetic states in a high-temperature paramagnetic nuclear spin system
In this paper we use the Nuclear Magnetic Resonance (NMR) to write eletronic
states of a ferromagnetic system into a high-temperature paramagnetic nuclear
spins. Through the control of phase and duration of radiofrequency pulses we
set the NMR density matrix populations, and apply the technique of quantum
state tomography to experimentally obtain the matrix elements of the system,
from which we calculate the temperature dependence of magnetization for
different magnetic fields. The effects of the variation of temperature and
magnetic field over the populations can be mapped in the angles of spins
rotations, carried out by the RF pulses. The experimental results are compared
to the Brillouin functions of ferromagnetic ordered systems in the mean field
approximation for two cases: the mean field is given by (i)
and (ii) , where is the external
magnetic field, and are mean field parameters. The
first case exhibits second order transition, whereas the second case has first
order transition with temperature hysteresis. The NMR simulations are in good
agreement with the magnetic predictions
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