259 research outputs found
Configuración Software de la directividad de arrays lineales
A line array can be defined as a column of
loudspeakers that is designed so that these work together to achieve a higher directivity. This paper presents an application that enables a user to rotate the wavefront of uniform line arrays. Theoretical background and details of the
implementation are provided. The validity of the application is tested with measurements of the directivity that are also compared with simulations.Este trabajo ha sido financiado Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech y el grupo de investigación Aplicación de las Tecnologías de la Información y Comunicaciones (PAI TIC-208)
Linear Strain Tensors on Hyperbolic Surfaces and Asymptotic Theories for Thin Shells
We perform a detailed analysis of the solvability of linear strain equations
on hyperbolic surfaces. We prove that if the surface is a smooth
noncharacteristic region, any first order infinitesimal isometry can be matched
to an infinitesimal isometry of an arbitrarily high order. The implications of
this result for the elasticity of thin hyperbolic shells are discussed
Análisis de regularidad en fibrilación ventricular: aplicación a registros de mapeado cardíaco
Las técnicas utilizadas en el análisis de la señal de fibrilación
ventricular (FV), obtenida mediante sistemas de mapeado
utilizando matrices de electrodos, extraen información del
proceso a partir de parámetros calculados principalmente en el
dominio del tiempo o de la frecuencia. El presente trabajo
plantea la aplicación del índice de regularidad (IR), propuesto
inicialmente para caracterizar la fibrilación auricular humana,
a la señal de FV en un modelo experimental de corazón animal.
Los resultados obtenidos muestran que el IR permite extraer
información de los mapas de FV no disponible de forma directa
cuando se estudian mediante los métodos clásicos en el tiempo o
la frecuencia, cuantificando el grado de modificación en la
morfología de las ondas de activación durante la FV
Use-wear analysis on the Early Neolithic blades from Castillejos de Montefrío (Granada)
El asentamiento de Castillejos de Montefrío constituye un yacimiento de primer orden para poder comprender el proceso de neolitización y el desarrollo de las primeras comunidades agricultoras y pastoras a lo largo de varios milenios en el sur peninsular. Aunque son muchas las publicaciones y los proyectos de investigación que se han generado a partir de la evidencia arqueológica recogida en este asentamiento, en el presente trabajo mostramos los resultados del análisis traceológico realizado sobre conjunto significativo de láminas –fundamentalmente aquellas que sin estar retocadas presentan huellas de uso– documentado en los niveles pertenecientes cronológicamente al Neolítico Antiguo. La información obtenida de estos estudios revela la importancia de este tipo de utillaje, así como ciertos aspectos sobre las prácticas económicas de estas comunidades prehistóricas.Castillejos de Montefrío (Granada) is an openair site located on the South of the Iberian Peninsula. This settlement is one of the most important sites to understand the neolithization process and the development of first farming societies for several millennia. In this paper we present the results of the use-wear analyses made on a selection of the flint blades (most of them without retouch) from the Early Neolithic levels. Our purpose, through the Traceology, is to recognize some activities developed in the settlement and provide some information about the site function. The results obtained show the importance of this kind of tools and reveal some economical aspects of the first farmers communities settled down in this region.European Research Council ERC-AdG-23056
Analysis of spatial and temporal evolution of regularity maps during ventricular fibrillation
The analysis of cardiac mapping allows investigating
the structure of ventricular fibrillation (VF). This work
analyzes regions of interest (ROI) on cardiac maps
obtained from the regularity analysis of VF records,
providing information about signal regularity at each
time instant and its spatial distribution.
Cardiac registers were obtained using a 240-
electrodes matrix located on left ventricle of isolated
rabbit heart. A Langendorff system was used to maintain
the heart perfusion. VF was induced by increased
frequencies. Two groups of records were considered:
control (G1: without physical training, N=10), and
trained (G2, N=9).
Records were processed in consecutive 4-second
segments. Regularity index (RI) was obtained for every
segment and channel. RI is a measure of similarity
degree among local activation waves for every channel.
A map with the RI value of each channel was computed
for the 82 register segments.
To analyze the spatial distribution of RI, a threshold
value was determined experimentally and applied to the
map in order to obtain the ROI. Two parameters were
calculated: ROI spatial number (ROIsn, a measure of
spatial fragmentation), and ROI spatial area (ROIsa, the
percentage of area map occupied by ROI).
In case of the time course of ROI, two additional
parameters were computed: the number of electrodes
which value had changed respect to the threshold in two
consecutive maps (ROIen, which is related with the
change size), and the cumulative absolute differences of
RI values for the electrodes which are changed (ROIed).
Obtained results for spatial analysis show that the
number of ROI is lower for trained rabbits (ROIsn; G1:
4.465±1.120; G2: 2.,227±0.623; p<0.001), but ROI
spatial area is greater than the control group (ROIsa;
G1: 76.235±5.355%; G2: 88.163±2.885%; p<0.001).
Time-course analysis shows that more electrodes change
between consecutive maps in the control group (ROIen,
G1: 22.455±6.702; G2: 13.877±2.485; p<0.001). No
significant differences were found for ROIed (G1:
18.509±6.932; G2: 18.619±4.196; n.s.).
To conclude, ROI analysis on RI maps applied to
trained and no trained rabbits groups shows that VF
cardiac response is more irregular and spatially
fragmented in no trained group. In addition, regularity
maps are more stable with time in trained group
Modifications on regularity and spectrum of ventricular fibrillation signal induced by physical training
The objective of this work is to study the modifications
on cardiac response during ventricular fibrillation (VF)
induced by physical training. The analysis was performed
in the frequency domain of VF, and the regularity of the
signal was also considered.
Two sets of records were acquired: control (G1:
without physical training, N=10), and trained (G2, N=9).
Cardiac registers were obtained using a 240-electrodes
matrix located on left ventricle of isolated rabbit heart. A
Langendorff system was used to maintain the heart
perfusion. VF was induced by increased frequencies.
To analyze the time course of VF, records were
processed in 4-second segments. For every segment and
channel, Welch periodogram with Hanning window, two
non-overlapped sections and zero padding, was
computed. Parameters considered in frequency domain
are: dominant frequency (DF) and normalized energy
(NE: spectral energy in the window DF±1Hz, normalized
by spectral energy in 5-35Hz band).
For every segment and channel, a regularity analysis
of VF was performed, obtaining the regularity index (RI),
which is a measure of similarity among local activation
waves present in every channel.
Mean values for the parameters (DF, NE and RI) of
the whole set of electrodes were computed for every
segment. Obtained results show that DF is lower for
trained rabbits (G1: 18.234±1, 241Hz; G2: 14.370±0,
866Hz; p<0.001). NE is greater for this group (G1:
0.140±0.006; G2: 0.263±0.017; p<0.001), suggesting a
greater spectral concentration around DF. Finally, a
greater regularity has been observed in the fibrillation
signal for trained group (IR, G1: 0.756±0.026; G2:
0.834±0.014; p<0.001).
As a summary, the results suggest that both spectral
characteristics and regularity of VF signal are clearly
different for G1 and G2 groups. The trained group (G2)
shows greater regularity, lower DF and spectral
dispersion. These factors should be interpreted as a more
stable cardiac response to V
Relación entre el espectro y la regularidad en la señal de fibrilación ventricular modificada por el ejercicio físico
El presente trabajo estudia las modificaciones intrínsecas que el
ejercicio físico produce en la respuesta cardíaca durante la FV.
Se han calculado dos parámetros relacionados con el espectro
de la señal (FD: frecuencia dominante, y EN: energía
normalizada), y otro relacionado con la regularidad de las OAL
(IR: índice de regularidad), Se ha realizado un análisis de
correlación entre los tres parámetros para valorar su grado de
complementariedad.
Se consideraron dos grupos de conejos: control (G1: sin
entrenamiento, N=10) y entrenados (G2, N=9). Se utilizó un
electrodo matricial de 240 canales localizado en ventrículo
izquierdo de corazón aislado de conejo perfundido mediante un
sistema de Langendorff. La FV se indujo por estimulación a
frecuencias crecientes.
Los resultados muestran que el grupo entrenado presenta una
mayor regularidad de la señal (IR: G1: 0,757+-0,091; G2:
0,845+-0,084; p<0.001), así como menor FD (G1:
18.23±2.96Hz; G2: 14.13+-1.73Hz; p<0.001) y dispersión
espectral (EN: G1: 0,138+-0.105; G2: 0,293+-0,176; p<0.001).
El análisis de las relaciones entre parámetros muestra
correlaciones significativas entre los parámetros para todos los
casos excepto para IR y FD en G2, por lo que estos parámetros
proporcionan información complementaria, ya que analizan
aspectos diferentes de la señal como la morfología de las ondas
de activación y su frecuencia. La existencia de correlación entre
ambas para G1 puede ser debida a otras causas, tales como las
modificaciones en ambos factores inducidas por la presencia de
reentradas o colisiones entre frentes de activación..
Como conclusión, los resultados obtenidos sugieren que el
entrenamiento físico produce una respuesta cardíaca más
estable ante FV, debida a modificaciones intrínsecas en las
características electrofisiológicas cardíacas
Analysis of the influence of parasympathetic postganglionic neurons on cardiac response in ventricular fibrillation
Physical training modifies the sympathetic-vagal
balance of autonomic nervous system. Previous studies
have shown that such training also produces intrinsic
modifications of cardiac electrophysiological properties
in isolated heart during Ventricular Fibrillation (VF).
Ten NZW trained rabbits were studied to test if the
modifications are related to the activity of
postganglionic parasympathetic neurons. Two records
per subject were acquired during VF: before (G1) and
after (G2) the infusion of atropine to inhibit the activity
of neurons. Mapping records were obtained using a
240-channel electrode array located in the left ventricle
of isolated heart (perfused by Langendorff system). VF
was induced by stimulation at increasing frequencies.
To analyze the time course of fibrillation, the records
were processed in 4-second consecutive segments. For
each channel and segment, the following parameters
were computed: 1) Dominant Frequency (DF), obtained
by the Welch periodogram b) Normalized Energy (NE)
in a frequency band centered at the DF; c) Regularity
Index (RI), which analyzes the similarity of local
activation waves in every segment and channel; d)
Coefficients of Variance of DF (CVDF), NE (CVNE)
and RI (CVRI).
For each segment, we obtained the average value of
each of the parameters analyzed for all electrodes. The
results are: a) DF (G1: 13.671 ± 0.509 Hz, G2: 14.783
± 0.455 Hz), b) NE (G1: 0.398 ± 0.014; G2: 0.380 ±
0.013); c) RI (G1: 0.855 ± 0.017; G2: 0.865 ± 0.015), d)
CVDF (G1: 0.109 ± 0.009; G2: 0.098 ± 0.008), e)
CVNE (G1: 0.398 ± 0.014; G2: 0.380 ± 0.013 ) f) CVRI
(G1: 0.084 ± 0.009; G2: 0.078 ± 0.008).
None of these parameters showed significant
differences between groups. Thus, the parasympathetic
postganglionic neurons seem to have no effect on the
cardiac response in VF due to physical training
Role of the Pi3k Regulatory Subunit in the Control of Actin Organization and Cell Migration
Cell migration represents an important cellular response that utilizes cytoskeletal reorganization as its driving force. Here, we describe a new signaling cascade linking PDGF receptor stimulation to actin rearrangements and cell migration. We demonstrate that PDGF activates Cdc42 and its downstream effector N-WASP to mediate filopodia formation, actin stress fiber disassembly, and a reduction in focal adhesion complexes. Induction of the Cdc42 pathway is independent of phosphoinositide 3-kinase (PI3K) enzymatic activity, but it is dependent on the p85α regulatory subunit of PI3K. Finally, data are provided showing that activation of this pathway is required for PDGF-induced cell migration on collagen. These observations show the essential role of the PI3K regulatory subunit p85α in controlling PDGF receptor–induced cytoskeletal changes and cell migration, illustrating a novel signaling pathway that links receptor stimulation at the cell membrane with actin dynamics
Indicaciones Límite de las Fracturas de Húmero con Clavo Endomedular Cerrojado
El tratamiento de las fracturas diafisarias del húmero ha entrado en controversia
en los últimos años, como lo refleja la literatura internacional. La problemática
aumenta cuando se trata de fracturas diafisarias límites que alcanzan la zona metafisaria
superior e inferior. En un intento de mejora terapéutica este grupo de autores ha testado un
clavo cerrojado para el húmero diseñado por Seidel. El promedio de seguimiento ha sido de
12 meses con un mínimo de 6 meses. El número de casos evaluados ha sido 6. Siguiendo la
cotación de Stewart, 4 de los seis pacientes obtuvieron resultados buenos o excelentes. Todos
los pacientes consolidaron sus fracturas en un período de tiempo normal, entre 3 y 5 meses,
con una media de 4 meses, 4 de los seis pacientes no se inmovilizaron con yeso en ningún momento.
La bondad y sencillez del método hace augurar buenos resultados en otros grupos ampliando
sus indicaciones.Treatment of dyaphyseal fractures of the humerus has been the
source of considerable controversy in recent years. The problem increases in
dimension when one is dealing with limiting diaphyseal fractures that invole the
upper and lower metaphyseal zone. In an attempt to improve the therapy of this
circunstance, the members of this research team have tested a locking nail for the
humerus designed by Seidel. The mean follow-up time has been 12 months, with a
minimum of six months. The number of cases evaluated was 6. According to the
scale of Stewart, four of the cases obtained good or excellent results. All the patients
consolidated their fractures within a normal period of time -between 3 and 5
months-, with a mean of 4 months. Four of the 6 patients wer e not immobilized with
paster at any time. The goodness and simplicity of the method are suggestive of
promising results in other groups by broadening its indications
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