1,081 research outputs found
Desarrollo local, educación e identidad cultural
Hay en nuestra sociedad un debate abierto sobre la relación
existente entre la identidad cultural de una comunidad
y su proceso de desarrollo. Se trata de una cuestión extremadamente
delicada, en la que intervienen múltiples factores
(sociales, económicos, pero especialmente políticos)
que hacen difíciles, en ocasiones, los análisis objetivos.
Aquí pretendemos mostrar el papel que juega la educación
en la puesta en valor de esa identidad cultural para lograr
un desarrollo local sostenible
Facing Non-Stationary Conditions with a New Indicator of Entropy Increase: The Cassandra Algorithm
We address the problem of detecting non-stationary effects in time series (in
particular fractal time series) by means of the Diffusion Entropy Method (DEM).
This means that the experimental sequence under study, of size , is explored
with a window of size . The DEM makes a wise use of the statistical
information available and, consequently, in spite of the modest size of the
window used, does succeed in revealing local statistical properties, and it
shows how they change upon moving the windows along the experimental sequence.
The method is expected to work also to predict catastrophic events before their
occurrence.Comment: FRACTAL 2002 (Spain
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Improving Visual Field Examination of the Macula Using Structural Information
Purpose: To investigate a novel approach for structure-function modeling in glaucoma to improve visual field testing in the macula.
Methods: We acquired data from the macular region in 20 healthy eyes and 31 with central glaucomatous damage. Optical coherence tomography (OCT) scans were used to estimate the local macular ganglion cell density. Perimetry was performed with a fundus-tracking device using a 10-2 grid. OCT scans were matched to the retinal image from the fundus perimeter to accurately map the tested locations onto the structural damage. Binary responses from the subjects to all presented stimuli were used to calculate the structure-function model used to generate prior distributions for a ZEST (Zippy Estimation by Sequential Testing) Bayesian strategy. We used simulations based on structural and functional data acquired from an independent dataset of 20 glaucoma patients to compare the performance of this new strategy, structural macular ZEST (MacS-ZEST), with a standard ZEST.
Results: Compared to the standard ZEST, MacS-ZEST reduced the number of presentations by 13% in reliable simulated subjects and 14% with higher rates (≥20%) of false positive or false negative errors. Reduction in mean absolute error was not present for reliable subjects but was gradually more important with unreliable responses (≥10% at 30% error rate).
Conclusions: Binary responses can be modeled to incorporate detailed structural information from macular OCT into visual field testing, improving overall speed and accuracy in poor responders.
Translational Relevance: Structural information can improve speed and reliability for macular testing in glaucoma practice
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Optical Coherence Tomography Angiography of Iris Nevus: A Case Report
Iris nevus is common: 6% of patients with suspected iris melanoma have lesions other than melanoma, and 36% of them are nevi. Iris nevus turns into melanoma in approximately 8% of cases at a mean of 15 years. This case report provides the first description of an iris tumor examined with iris optical coherence tomography angiography (OCTA) compared to iris fluorescein angiography (IFA). A 60-year-old man with a diagnosis of iris nevus in the left eye was referred to our department for IFA and iris OCTA. The iris vasculature in IFA was visible only in the early phases, but not clearly. OCTA, however, gave visualization of the vascular network and very precisely defined the vessels of the whole lesion, except for the pupillary portion, which was masked by superficial pigment accumulations. IFA and iris OCTA can add information about the vascular architecture compared to slit-lamp biomicroscopy, ultrasound biomicroscopy, and anterior-segment OCT. However, IFA is time-consuming and invasive and can – very occasionally – cause serious adverse reactions. In contrast, OCTA defines the texture of the iris vasculature better. In conclusion, OCTA is a new method, easy to execute, needing no dye injection, and provides useful information on the vascular network of iris lesions. It could therefore be helpful in the diagnosis and follow-up of these lesions
Educación para el desarrollo humano, educación como ayuda al crecimiento
El fenómeno social de la pobreza, es una de las mayores preocupaciones de las políticas
de desarrollo a escala mundial, y es también uno de los más dificiles de solucionar. A pesar de
los logros conseguidos hasta el momento, no se ha podido romper su presencia cíclica en
todos los países del planeta.
Con la mirada esperanzada puesta en el futuro, se propone en este trabajo titulado
“Educación para el desarrollo humano, educación como ayuda al crecimiento”, una tesis
sencilla: se trata de procurar prepapar el desarrollo, a través de la educación, en la infancia. Lo
sugerente de la propuesta es que, aquí, se entiende la educación como ayuda al crecimiento y
que el desarrollo para ser eficaz debe ser puesto en marcha en el ámbito más cercano a las
personas: el local o comunitario. Así, y como forma de luchar contra la pobreza, se propone
una educación que, desde la infancia, prepare a los individuos para actuar de forma libre,
comprometida y responsable en la mejora de las condiciones de vida que le rodean. Cuánto
más crezca cada miembro de la comunidad como persona, más activamente podrá luchar
contra la pobreza y a favor de su propio desarrollo y el de sus convecinos
Memory beyond memory in heart beating: an efficient way to detect pathological conditions
We study the long-range correlations of heartbeat fluctuations with the
method of diffusion entropy. We show that this method of analysis yields a
scaling parameter that apparently conflicts with the direct evaluation
of the distribution of times of sojourn in states with a given heartbeat
frequency. The strength of the memory responsible for this discrepancy is given
by a parameter , which is derived from real data. The
distribution of patients in the (, )-plane yields a neat
separation of the healthy from the congestive heart failure subjects.Comment: submitted to Physical Review Letters, 5 figure
L\'{e}vy scaling: the Diffusion Entropy Analysis applied to DNA sequences
We address the problem of the statistical analysis of a time series generated
by complex dynamics with a new method: the Diffusion Entropy Analysis (DEA)
(Fractals, {\bf 9}, 193 (2001)). This method is based on the evaluation of the
Shannon entropy of the diffusion process generated by the time series imagined
as a physical source of fluctuations, rather than on the measurement of the
variance of this diffusion process, as done with the traditional methods. We
compare the DEA to the traditional methods of scaling detection and we prove
that the DEA is the only method that always yields the correct scaling value,
if the scaling condition applies. Furthermore, DEA detects the real scaling of
a time series without requiring any form of de-trending. We show that the joint
use of DEA and variance method allows to assess whether a time series is
characterized by L\'{e}vy or Gauss statistics. We apply the DEA to the study of
DNA sequences, and we prove that their large-time scales are characterized by
L\'{e}vy statistics, regardless of whether they are coding or non-coding
sequences. We show that the DEA is a reliable technique and, at the same time,
we use it to confirm the validity of the dynamic approach to the DNA sequences,
proposed in earlier work.Comment: 24 pages, 9 figure
Compression and diffusion: a joint approach to detect complexity
The adoption of the Kolmogorov-Sinai (KS) entropy is becoming a popular
research tool among physicists, especially when applied to a dynamical system
fitting the conditions of validity of the Pesin theorem. The study of time
series that are a manifestation of system dynamics whose rules are either
unknown or too complex for a mathematical treatment, is still a challenge since
the KS entropy is not computable, in general, in that case. Here we present a
plan of action based on the joint action of two procedures, both related to the
KS entropy, but compatible with computer implementation through fast and
efficient programs. The former procedure, called Compression Algorithm
Sensitive To Regularity (CASToRe), establishes the amount of order by the
numerical evaluation of algorithmic compressibility. The latter, called Complex
Analysis of Sequences via Scaling AND Randomness Assessment (CASSANDRA),
establishes the complexity degree through the numerical evaluation of the
strength of an anomalous effect. This is the departure, of the diffusion
process generated by the observed fluctuations, from ordinary Brownian motion.
The CASSANDRA algorithm shares with CASToRe a connection with the Kolmogorov
complexity. This makes both algorithms especially suitable to study the
transition from dynamics to thermodynamics, and the case of non-stationary time
series as well. The benefit of the joint action of these two methods is proven
by the analysis of artificial sequences with the same main properties as the
real time series to which the joint use of these two methods will be applied in
future research work.Comment: 27 pages, 9 figure
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Effect of prophylactic timolol 0.1% gel on intraocular pressure after an intravitreal injection of ranibizumab: a randomized study
Purpose: The purpose of this study is to make a prospective evaluation of the effect of timolol 0.1% eye gel on short-term intraocular pressure (IOP) after an intravitreal injection (IVI) of ranibizumab.
Participants and methods: One hundred and fifty eyes of 150 IVI-naïve patients with macular edema caused by various pathological conditions (age-related macular degeneration, central or branch retinal vein occlusion, and diabetic retinopathy) were scheduled to undergo an IVI of ranibizumab (0.5 mg/0.05 cc). The patients were randomly divided into three groups: 50 were not treated with timolol before the IVI (group 1); 50 received an instillation of timolol 0.1% eye gel the evening before the IVI (group 2); and 50 received an instillation of timolol 0.1% eye gel 2 hours before the IVI (group 3). The incidence of clinically significant intraocular hypertensive spikes (>25 mmHg and >40 mmHg) was then assessed.
Results: Our findings showed that mean IOP at baseline was significantly higher than at both 5 and 60 minutes after IVI (P25 mmHg were recorded at either time in 27 patients (54%) in group 1, 23 patients (44%) in group 2, and 24 patients (48%) in group 3. None of the between-group differences were significant. Spikes of >40 mmHg (which were only detected 5 minutes after IVI) were recorded in nine (18%), eight (16%), and one patient (2%) in groups 1, 2, and 3, respectively. The only significant difference was between the control and group 3 (P=0.012).
Conclusion: An increase in IOP after antivascular endothelial growth factor IVI is a frequent complication. The prophylactic use of timolol 0.1% gel effectively reduced the mean IOP when administered 2 hours before IVI and was also effective in preventing dangerous IOP spikes of >40 mmHg. It is therefore recommended before IVIs as a means of preventing emergency procedures and preserving the health of the optic nerve
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