450 research outputs found
Time dependent transformations in deformation quantization
We study the action of time dependent canonical and coordinate
transformations in phase space quantum mechanics. We extend the covariant
formulation of the theory by providing a formalism that is fully invariant
under both standard and time dependent coordinate transformations. This result
considerably enlarges the set of possible phase space representations of
quantum mechanics and makes it possible to construct a causal representation
for the distributional sector of Wigner quantum mechanics.Comment: 16 pages, to appear in the J. Math. Phy
A new proof of the Herman-Avila-Bochi formula for Lyapunov exponents of SL(2,R)-cocycles
We study the geometry of the action of SL(2,R) on the projective line in
order to present a new and simpler proof of the Herman-Avila-Bochi formula.
This formula gives the average Lyapunov exponent of a class of 1-families of
SL(2,R)-cocycles.Comment: 13 pages, 2 figure
Generalized Weyl-Wigner map and Vey quantum mechanics
The Weyl-Wigner map yields the entire structure of Moyal quantum mechanics
directly from the standard operator formulation. The covariant generalization
of Moyal theory, also known as Vey quantum mechanics, was presented in the
literature many years ago. However, a derivation of the formalism directly from
standard operator quantum mechanics, clarifying the relation between the two
formulations is still missing. In this paper we present a covariant
generalization of the Weyl order prescription and of the Weyl-Wigner map and
use them to derive Vey quantum mechanics directly from the standard operator
formulation. The procedure displays some interesting features: it yields all
the key ingredients and provides a more straightforward interpretation of the
Vey theory including a direct implementation of unitary operator
transformations as phase space coordinate transformations in the Vey idiom.
These features are illustrated through a simple example.Comment: 15 pages, LaTe
Implementation and Performance Analysis of a Low Resolution OFDM System Prototype With Low Cost Hardware
The present work focus on the implementation and analyze of performance of a
low-resolution OFDM system prototype with low-cost hardware. A software defined
radio (SDR) system was chosen in this implementation due to its various
advantages over a traditional radio system. Among the options of SDR devices
available, the use of universal software radio peripherals (USRP) was avoided
due to its high cost, despite its popularity in this field of research.
Alternatively, a combination of two low-cost SDRs, "Hackrf One" and "RTL- SDR
Blog V3" with the GNU Radio, a popular, free and open source radio software,
were used. Thus, it was possible to emulate the behavior of a low resolution
ADC in the receiver, characterize its performance and estimate its energy
savings. This allowed us to determine the feasibility of building a component
with the analog-to-digital conversion function with few bits of resolution. We
conclude that the performance of an ADC with at least 5 bits of resolution is
pretty reasonable and that this reduction in the number of bits, in comparison
to 8-bit ADC, represents a fairly expressive energy saving
Generic dynamics of 4-dimensional C2 Hamiltonian systems
We study the dynamical behaviour of Hamiltonian flows defined on
4-dimensional compact symplectic manifolds. We find the existence of a
C2-residual set of Hamiltonians for which every regular energy surface is
either Anosov or it is in the closure of energy surfaces with zero Lyapunov
exponents a.e. This is in the spirit of the Bochi-Mane dichotomy for
area-preserving diffeomorphisms on compact surfaces and its continuous-time
version for 3-dimensional volume-preserving flows
Analytical and numerical analysis of the behaviour of RC beams flexural strengthened with CFRP
Experimental research regarding the flexural strengthening of reinforced concrete
(RC) structures with Carbon Fibre Reinforced (CFRP) systems using the Externally Bonded Reinforcing
(EBR) and the Near Surface Mounted (NSM) techniques has been carried out at the
University of Minho. Considering the experimental results of this research, the performance of
the ACI and fib formulations for the EBR flexural strengthening was appraised in this paper.
The same was done in terms of NSM technique adopting for the CFRP debonding strain a value
that is 70% of the CFRP ultimate strain, according to the recommendations of the ACI Committee
440. However, the experimental results show that the CFRP debonding strain is dependent
on the CFRP percentage and existing longitudinal steel reinforcement ratio. To estimate an
equation for the prediction of the CFRP debonding strain, which takes into account these parameters,
a numerical model was applied to the simulation of the tests carried out.(undefined
Multivariate geostatistical analysis of stable isotopes in Portuguese varietal extra virgin olive oils
Stable isotope contents of carbon, hydrogen and oxygen are known to reflect the geo-climatic conditions under
which olives grown. This study aims to unravel the correlation between some of the main geographic variables
and the isotopic composition of different Portuguese varietal extra virgin olive oil (EVOO) samples. Thus, the
isotopic composition (δ13C, δ18O and δ2H) of 38 EVOO samples from 11 olive varieties from 2 Portuguese
regions (Alentejo and Trás-os-Montes) was studied using an elemental analyzer coupled to an isotope ratio mass
spectrometry. Multivariate analysis indicated that bulk δ13C, δ2H and δ18O values were enough to significantly
(P < 0.05) predict altitude, latitude, longitude, temperature, rainfall, and sea distance. This work showed that
the assessment of EVOO isotopic composition give information not only on the geographic origin, but also on the
environmental conditions. To the best of our knowledge, this is the first report on bulk isotopic composition of
Portuguese EVOOs.This work was funded by European Regional Development Fund
(FEDER) and National Funds through Foundation for Science and
Technology (FCT) under Project “Por3O - Portuguese Olive Oil Omics
for traceability and authenticity - PTDC/AGRPRO/2003/2014, and by
National Funds through FCT - Foundation for Science and Technology
under the Projects UIDB/05183/2020 and UID/AGR/00690/2019.
Pedro N. Jiménez-Morillo is acknowledged for statistical assistance.info:eu-repo/semantics/publishedVersio
Revisiting 30 years of biofunctionalization and surface chemistry of inorganic nanoparticles for nanomedicine
FP7-PEOPLE-2013-IOF, Project no. 626386
PEst-OE/SAU/U10009/2011-14
MAT2011-26851-C02-01In the last 30 years we have assisted to a massive advance of nanomaterials in material science. Nanomaterials and structures, in addition to their small size, have properties that differ from those of larger bulk materials, making them ideal for a host of novel applications. The spread of nanotechnology in the last years has been due to the improvement of synthesis and characterization methods on the nanoscale, a field rich in new physical phenomena and synthetic opportunities. In fact, the development of functional nanoparticles has progressed exponentially over the past two decades. This work aims to extensively review 30 years of different strategies of surface modification and functionalization of noble metal (gold) nanoparticles, magnetic nanocrystals and semiconductor nanoparticles, such as quantum dots. The aim of this review is not only to provide in-depth insights into the different biofunctionalization and characterization methods, but also to give an overview of possibilities and limitations of the available nanoparticles.publishersversionpublishe
Entropic Gravity, Phase-Space Noncommutativity and the Equivalence Principle
We generalize E. Verlinde's entropic gravity reasoning to a phase-space
noncommutativity set-up. This allow us to impose a bound on the product of the
noncommutative parameters based on the Equivalence Principle. The key feature
of our analysis is an effective Planck's constant that naturally arises when
accounting for the noncommutative features of the phase-space.Comment: 12 pages. Version to appear at the Classical and Quantum Gravit
Squaraine dyes derived from indolenine and benzo[e]indole as potential fluorescent probes for HSA detection and antifungal agents
Four squaraine dyes derived from 2,3,3-trimethylindolenine and 1,1,2-trimethyl-1H-benzo[e]indole with different combinations of barbituric groups attach to the central ring, having ester groups and alkyl chains in the nitrogen atoms of heterocyclic rings were synthesized. These dyes were fully characterized and their photophysical behavior was studied in ethanol and phosphate-buffered saline solution. Absorption and emission bands between 631 and 712 nm were detected, with the formation of aggregates in aqueous media, which is typical of this class of dyes. Tests carried out with 1,3-diphenylisobenzofuran allowed us to verify the ability of the dyes to produce singlet oxygen. The interaction of synthesized dyes with human serum albumin (HSA) was also evaluated, being demonstrated a linear correlation between fluorescence intensity and protein concentration. The antifungal potential of the dyes against the yeast Saccharomyces cerevisiae was evaluated using a broth microdilution assay. In order to test the photosensitizing capacity of the synthesized dyes, tests were carried out in the dark and with irradiation, using a custom-built light-emitting diode that emits close to the absorption wavelength of the studied dyes. The results showed that the interaction of dyes with HSA and the antifungal activity depends on the different structural modifications of the dyes.We thanks to Fundação para a Ciência e Tecnologia (FCT), Comissão de Coordenação e Desenvolvimento Regional do Norte (CCDR-N) and FEDER (European Fund for Regional Development)-COMPETEQREN-EU for financial support to the research centers CQ/UM (UIDB/00686/2020), CBMA (UID/BIA/04050/2020), CQ/VR (UID/QUI/UI0616/2019) and CICSUBI (POCI-01-0145-FEDER-007491), as well as PhD grants to V.S.D.G. (UMINHO/BD/43/2016) and J.C.C.F. (SFRH/BD/133207/2017)
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