7,872 research outputs found
Shiga Toxin Detection Methods : A Short Review
The Shiga toxins comprise a family of related protein toxins secreted by
certain types of bacteria. Shigella dysenteriae, some strain of Escherichia
coli and other bacterias can express toxins which caused serious complication
during the infection. Shiga toxin and the closely related Shiga-like toxins
represent a group of very similar cytotoxins that may play an important role in
diarrheal disease and hemolytic-uremic syndrome. The outbreaks caused by this
toxin raised serious public health crisis and caused economic losses. These
toxins have the same biologic activities and according to recent studies also
share the same binding receptor, globotriosyl ceramide (Gb3). Rapid detection
of food contamination is therefore relevant for the containment of food-borne
pathogens. The conventional methods to detect pathogens, such as
microbiological and biochemical identification are time-consuming and
laborious. The immunological or nucleic acid-based techniques require extensive
sample preparation and are not amenable to miniaturization for on-site
detection. In the present are necessary of techniques of rapid identification,
simple and sensitive which can be employed in the countryside with
minimally-sophisticated instrumentation. Biosensors have shown tremendous
promise to overcome these limitations and are being aggressively studied to
provide rapid, reliable and sensitive detection platforms for such
applications.Comment: 16 pages, 2 figure
Tourism and productivity: Case study of the hotel and catering industry in the Andalusian region
The object of this paper is to analyse the situation and evolution of the productivity of the tourism industry in the Andalusian region, and more specifically of the hotel and catering branch, relating it to the organisational structure of its businesses. First of all, the issue of the definition and limitation of the concept of productivity applied to the services sector is addressed, as traditionally this concept is focused on manufacturing, and the different ways of measuring and the analysis methods are reviewed. Then, using the accounting information provided by the Balances Centre of Andalusia (CBA), the general features of the organisational structure of the hotel and catering industry in de Andalusian region, stratifying the samples by the size of the companies and examining the medium size of the Andalusian hotel and catering businesses. Once the organisational structure of the sector is analysed, it is related to the state and evolution of its productivity, using a simple ratio between the brute added value and the personnel expenses, and completing this analysis with a relative efficiency index, the Baldwin efficiency index, with which the technical efficiency of each company is compared to the mass of most efficient companies. As a result of this research it is observed that the productivity indexes increase as web as the size of the companies and during the considered period, especially in the case of the medium sized and large companies. Nevertheless, these productivity increases are less relevant than the increase of employment, especially in case of smaller companies.
Minimal formulation of the linear spatial analysis of capillary jets: Validity of the two-mode approach
A rigorous and complete formulation of the linear evolution of harmonically stimulated
capillary jets should include infinitely many spatial modes to account for arbitrary exit
conditions [J. Guerrero et al., J. Fluid Mech. 702, 354 (2012)]. However, it is not rare to
find works in which only the downstream capillary dominant mode, the sole unstable one,
is retained, with amplitude determined by the jet deformation at the exit. This procedure
constitutes an oversimplification, unable to handle a flow rate perturbation without jet
deformation at the exit (the most usual conditions). In spite of its decaying behavior, the
other capillary mode (subdominant) must be included in what can be called a “minimal
linear formulation.” Deformation and mean axial velocity amplitudes at the jet exit are the
two relevant parameters to simultaneously find the amplitudes of both capillary modes.
Only once these amplitudes are found, the calculation of the breakup length may be
eventually simplified by disregarding the subdominant mode. Simple recipes are provided
for predicting the breakup length, which are checked against our own numerical simulations.
The agreement is better than in previous attempts in the literature. Besides, the limits of
validity of the linear formulation are explored in terms of the exit velocity amplitude, the
wave number, the Weber number, and the Ohnesorge number. Including the subdominant
mode extends the range of amplitudes for which the linear model gives accurate predictions,
the criterion for keeping this mode being that the breakup time must be shorter than a
given formula. It has been generally assumed that the shortest intact length happens for the
stimulation frequency with the highest growth rate. However, we show that this correlation
is not strict because the amplitude of the dominant mode has a role in the breakup process
and it depends on the stimulation frequency.Ministerio de Economía, Industria y Competitividad, Spain, under Contract No. FIS2014-25161Junta de Andalucía under Contract No. P11-FQM-791
Giovanni Parodi (Editor) Alfabetización académica y profesional en el siglo XXI: leer y escribir desde las disciplinas
Control de agarre y posicionamiento en una plataforma robot con sensores táctiles
En este artículo se presenta una plataforma
formada por un brazo robot de 5 grados de
libertad y una pinza robot de 1 sólo grado de
libertad, con superficies táctiles. Este sistema
obtiene, en tiempo real, las distribuciones de
presión cuando un objeto ha sido agarrado,
produciendo una realimentación del control de la
posición y fuerza
Diseño y prototipado mediante impresión 3D de antenas para comunicaciones por satélite
Este Trabajo Fin de Grado consiste en la comparación de diferentes antenas de bocina circulares. Se trabaja en condiciones de espacio libre y en frecuencias en banda K, concretamente entre 17 GHz y 20 GHz.
Primero se introducirán una serie de conceptos básicos usados a lo largo de este TFG, tales como, teoría de guías de onda, teoría de antenas, diagrama de radicación, coeficiente de reflexión, ganancia…
Posteriormente se desarrolla un programa que grafique el campo de los diferentes modos que se propagan en la guía de onda circular, así como otra versión que realice la suma ponderada de los mismos, mostrando en la memoria algunos ejemplos.
A continuación, se diseñan una antena de bocina monomodo y una antena de bocina multimodo siguiendo el ejemplo de la antena de bocina Potter. Esta última se diseña para que propague el modo Híbrido HE11, previamente graficado en el programa Matlab.
Se comparan los diferentes resultados de las dos antenas diseñadas, ambas de la misma longitud total, en cuanto a reflexión y a radiación, observando que las dos tienen diferentes aspectos positivos.
Para construir la antena se ve la necesidad de diseñar un transformador al no disponer de una transición de guía circular a coaxial. Por lo que con el mismo programa se diseña un transformador de guía de onda circular a guía de onda rectangular, concretamente la WR51.
Se añade a ambas antenas de bocina el transformador y el flange WR51 y se comparan las simulaciones.
Por problemas técnicos ajenos a este TFG solo se construye la antena de bocina monomodo y se mide en la cámara anecoica, comparando las medidas con las simulaciones. Los resultados varían respecto a las simulaciones teóricas debido a las pérdidas de los materiales, ya que no son ideales
Laparoscopic image analysis for automatic tracking of surgical tools
Laparoscopy is a surgical technique nowadays embedded in the clinical routine. Recent researches have been focused on analysing video information captured by the endoscope for extracting cues useful for surgeons, such as depth information. In particular, the 3D pose estimation of the surgical tools presents three important added values: (1) to extract objective parameters for the surgical training stage, (2) to develop an image-guided surgery based on the knowledge of the surgery tools localization, (3) to design new roboticsystems for an automatic laparoscope positioning, according to the visual feedback. Tool’s shape and orientation in the image is the key to get its 3D position. This work presents an image analysis for automatic laparoscopic tool’s detection along the recorded video without extra tool markers, using an edges detection strategy. Also, this analysis includes a previous stage of barrel distortion correction for videoendoscopic image
A new multisensor software architecture for movement detection: Preliminary study with people with cerebral palsy
A five-layered software architecture translating movements into mouse clicks has been developed and tested on an
Arduino platform with two different sensors: accelerometer and flex sensor. The archi-tecture comprises low-pass
and derivative filters, an unsupervised classifier that adapts continuously to the strength of the user's movements and
a finite state machine which sets up a timer to prevent in-voluntary movements from triggering false positives.
Four people without disabilities and four people with cerebral palsy (CP) took part in the experi-ments. People
without disabilities obtained an average of 100% and 99.3% in precision and true positive rate (TPR) respectively and
there were no statistically significant differences among type of sensors and placement. In the same experiment,
people with disabilities obtained 97.9% and 100% in precision and TPR respectively. However, these results worsened
when subjects used the system to access a commu-nication board, 89.6% and 94.8% respectively. With their usual
method of access-an adapted switch- they obtained a precision and TPR of 86.7% and 97.8% respectively. For 3-outof-
4 participants with disabilities our system detected the movement faster than the switch.
For subjects with CP, the accelerometer was the easiest to use because it is more sensitive to gross motor motion
than the flex sensor which requires more complex movements. A final survey showed that 3-out-of-4 participants
with disabilities would prefer to use this new technology instead of their tra-ditional method of access
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