722 research outputs found
With a Little Help From our Friends: âGlobalâ Incentives and âLocalâ Challenges to Feminist Politics in Brazil
What are the major challenges facing feminists working to achieve gender justice in the context of development today? How are we to go about facing them? These were two of the major questions addressed by the âGender Myths and Feminist Fablesâ workshop participants, but to which no single solution was to be found. My own reactions
are best conveyed by outlining current
circumstances in Brazil. These reflect my close involvement in recent developments which, I believe, should foster the forging of a more equitable Brazilian society
Study on the use of Typha spp. for the phytotreatment of water contaminated with ibuprofen
Several studies on phytotoxic effects caused by organic xenobiotics and their
removal from water by macrophytes have already been performed to evaluate the
usefulness of these plants for phytoremediation technologies. In this context,
a study was conducted to assess Typha spp.âs ability to withstand and remove,
from water, the non-steroidal anti-inflammatory drug ibuprofen. For an initial
ibuprofen concentration of 20 mgL 1, Typha removed nearly 60% of it within the
first 24 h, attaining over 99% removal by the end of the assay (21 days). Exposure
to higher ibuprofen concentrations did affect Typhaâs growth but, by the end of
the assays, plantsâ growth as well as photosynthetic pigments approached normal
values. An alteration in antioxidant enzymes activities (superoxide dismutase,
catalase, guaiacol peroxidase) indicated that both roots and leaves were affected
by the xenobiotic. Eventually, Typha seemed able to cope with ibuprofenâs
induced oxidative damage suggesting its ability for phytotreatment of waters
contaminated with ibuprofen
Control tunning approach and digital filter application for competitive line follower robot
This research describes the development of a control
strategy to optimize a competitive line follower robot for standard
races. The innovative approach stems from the WolfBotz team
at CEFET/RJ, presenting a thorough exploration of mathematical
foundations, hardware design, control analysis, and how
to implement this system in a microcontroller. This research
complements a previous work that shows all the regulations used
in Brazilian competitions and describes the controllers used in
the system, such as angular and linear control. This research
emphasizes all the changes between the two versions of Line
Follower robots. The emphasis on mathematical foundations and
integrating digital signal processing techniques like digital filters
set the stage for robust sensor data interpretation. The tuning
and optimization of dual controllers for track stability and linear
velocity regulation represent a significant innovation, augmenting
the robotâs overall performance.The authors would like to thank CEFET/RJ and the Brazilian
research agencies CAPES, CNPq, and FAPERJ for supporting
this work. Besides, the authors are grateful to the
Foundation for Science and Technology (FCT, Portugal) for
financial support through national funds FCT/MCTES (PIDDAC)
to CeDRI (UIDB/05757/2020 and UIDP/05757/2020)
and SusTEC (LA/P/0007/2021).info:eu-repo/semantics/publishedVersio
Higher Order Evaluation of the Critical Temperature for Interacting Homogeneous Dilute Bose Gases
We use the nonperturbative linear \delta expansion method to evaluate
analytically the coefficients c_1 and c_2^{\prime \prime} which appear in the
expansion for the transition temperature for a dilute, homogeneous, three
dimensional Bose gas given by T_c= T_0 \{1 + c_1 a n^{1/3} + [ c_2^{\prime}
\ln(a n^{1/3}) +c_2^{\prime \prime} ] a^2 n^{2/3} + {\cal O} (a^3 n)\}, where
T_0 is the result for an ideal gas, a is the s-wave scattering length and n is
the number density. In a previous work the same method has been used to
evaluate c_1 to order-\delta^2 with the result c_1= 3.06. Here, we push the
calculation to the next two orders obtaining c_1=2.45 at order-\delta^3 and
c_1=1.48 at order-\delta^4. Analysing the topology of the graphs involved we
discuss how our results relate to other nonperturbative analytical methods such
as the self-consistent resummation and the 1/N approximations. At the same
orders we obtain c_2^{\prime\prime}=101.4, c_2^{\prime \prime}=98.2 and
c_2^{\prime \prime}=82.9. Our analytical results seem to support the recent
Monte Carlo estimates c_1=1.32 \pm 0.02 and c_2^{\prime \prime}= 75.7 \pm 0.4.Comment: 29 pages, 3 eps figures. Minor changes, one reference added. Version
in press Physical Review A (2002
Evaluation of diabetic foot amputation rate
Acta Med Port. 2003 Nov-Dec;16(6):373-80. Epub 2003 Dec 1.
[Evaluation of diabetic foot amputation rate].
[Article in Portuguese]
Horta C, Vilaverde J, Mendes P, Gonçalves I, Serra L, Pinto PS, Almeida R, Carvalho R, Dores J, Serra MB.
Serviços de Endocrinologia, Ortopedia e Cirurgia Vascular, Hospital Geral de Santo António, Porto.
Abstract
In 1987, it was created the first portuguese Diabetic Foot Clinic in Oporto, at the Hospital Geral de Santo AntĂłnio. The distinction between neuropathic and ischaemic foot was the key stone to reduce drastically the rate of major amputations in the first two years of activity. Since then and until 1995 the rate of major amputations had stabilised around 8%. The aim of the present study was to evaluate if there was any change in the last three years. A retrospective study was performed reviewing the clinical files of 843 new patients between 1998 and 2000. The 593 patients who presented with a foot ulcer with or without infection were selected: 60.4% with neuropathic foot and 39.6% with ischaemic one. Overall, 31 of the 593 patients with ulcer or infection were treated with major amputation (5.2%). There was a statistical difference between the major amputation outcome among the two types of foot (p < 0.001). Necrosis showed to carry a poor prognosis (30.7% in ischaemic foot vs 8,3% in neuropathic, p = 0.024). There was no further statistical significance for age, sex, type or duration of diabetes as risk factors for major amputation. This retrospective study has showed a slight reduction in the rate of major amputations since 1995. Poor prognosis was related to necrosis and ischaemic foot. Further improvement requires harder investment in patients' education, as well as in alerting the primary health care physicians, for the most unpredictable catastrophic complication of diabetes.
PMID: 15631847 [PubMed - indexed for MEDLINE
General dissipation coefficient in low-temperature warm inflation
In generic particle physics models, the inflaton field is coupled to other
bosonic and fermionic fields that acquire large masses during inflation and may
decay into light degrees of freedom. This leads to dissipative effects that
modify the inflationary dynamics and may generate a nearly-thermal radiation
bath, such that inflation occurs in a warm rather than supercooled environment.
In this work, we perform a numerical computation and obtain expressions for the
associated dissipation coefficient in supersymmetric models, focusing on the
regime where the radiation temperature is below the heavy mass threshold. The
dissipation coefficient receives contributions from the decay of both on-shell
and off-shell degrees of freedom, which are dominant for small and large
couplings, respectively, taking into account the light field multiplicities. In
particular, we find that the contribution from on-shell decays, although
Boltzmann-suppressed, can be much larger than that of virtual modes, which is
bounded by the validity of a perturbative analysis. This result opens up new
possibilities for realizations of warm inflation in supersymmetric field
theories.Comment: 25 pages, 13 figures; revised version with new results added;
published in JCA
Symmetry Nonrestoration in a Resummed Renormalized Theory at High Temperature
We reinvestigate the interesting phenomenon of symmetry nonrestoration at
high temperature in the multifield O(N_1) X O(N_2) model. We apply modified
self-consistent resummation (MSCR) in order to obtain the scalar dressed masses
and find in what circumstances a resummed multifield theory which has symmetry
(non)restoration can be renormalized. It is shown that, aside from the
consistency of the MSCR method, the basic ingredient that guarantees the
renormalization of a multifield model within a resummation approach is the T^2
mass behavior of field theory at high temperature.Comment: 14 pages, 1 ps figure, revtex, Phys. Rev. D versio
The impact of educational robots as learning tools in specific technical classes in undergraduate education
The use of mobile robots in the classroom has gained
increasing attention in recent years due to their potential to
enhance student engagement and facilitate personalized learning.
This research presents the insertion of mobile robots as a
hands-on learning experience in Control and Servomechanisms
II and Signal Processing II classes. This work also addresses
the challenges and limitations of using mobile robots in the
classroom, including technical difficulties. The students were
evaluated during the code implementation in the practical
exercises. Besides, a form was provided to them in order to
assess the impact of these robots as part of the pedagogical
practice. From the studentsâ positive feedback, it was possible to
conclude that the mobile robots were well-accepted. Besides, the
robots enhanced Control Systems classes and improved studentsâ
learning outcomes.The authors would like to thank CEFET/RJ, UFF, UFRJ,
and the Brazilian research agencies CAPES, CNPq, and
FAPERJ. Besides, the authors are grateful to the Foundation
for Science and Technology (FCT, Portugal) for financial
support through national funds FCT/MCTES (PIDDAC)
to CeDRI (UIDB/05757/2020 and UIDP/05757/2020) and
SusTEC (LA/P/0007/2021).info:eu-repo/semantics/publishedVersio
Asymptotically Improved Convergence of Optimized Perturbation Theory in the Bose-Einstein Condensation Problem
We investigate the convergence properties of optimized perturbation theory,
or linear expansion (LDE), within the context of finite temperature
phase transitions. Our results prove the reliability of these methods, recently
employed in the determination of the critical temperature T_c for a system of
weakly interacting homogeneous dilute Bose gas. We carry out the explicit LDE
optimized calculations and also the infrared analysis of the relevant
quantities involved in the determination of in the large-N limit, when
the relevant effective static action describing the system is extended to O(N)
symmetry. Then, using an efficient resummation method, we show how the LDE can
exactly reproduce the known large-N result for already at the first
non-trivial order. Next, we consider the finite N=2 case where, using similar
resummation techniques, we improve the analytical results for the
nonperturbative terms involved in the expression for the critical temperature
allowing comparison with recent Monte Carlo estimates of them. To illustrate
the method we have considered a simple geometric series showing how the
procedure as a whole works consistently in a general case.Comment: 38 pages, 3 eps figures, Revtex4. Final version in press Phys. Rev.
Self-Similar Factor Approximants
The problem of reconstructing functions from their asymptotic expansions in
powers of a small variable is addressed by deriving a novel type of
approximants. The derivation is based on the self-similar approximation theory,
which presents the passage from one approximant to another as the motion
realized by a dynamical system with the property of group self-similarity. The
derived approximants, because of their form, are named the self-similar factor
approximants. These complement the obtained earlier self-similar exponential
approximants and self-similar root approximants. The specific feature of the
self-similar factor approximants is that their control functions, providing
convergence of the computational algorithm, are completely defined from the
accuracy-through-order conditions. These approximants contain the Pade
approximants as a particular case, and in some limit they can be reduced to the
self-similar exponential approximants previously introduced by two of us. It is
proved that the self-similar factor approximants are able to reproduce exactly
a wide class of functions which include a variety of transcendental functions.
For other functions, not pertaining to this exactly reproducible class, the
factor approximants provide very accurate approximations, whose accuracy
surpasses significantly that of the most accurate Pade approximants. This is
illustrated by a number of examples showing the generality and accuracy of the
factor approximants even when conventional techniques meet serious
difficulties.Comment: 22 pages + 11 ps figure
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