1,219 research outputs found
A Cellular Automaton Model for the Traffic Flow in Bogota
In this work we propose a car cellular automaton model that reproduces the
experimental behavior of traffic flows in Bogot\'a. Our model includes three
elements: hysteresis between the acceleration and brake gaps, a delay time in
the acceleration, and an instantaneous brake. The parameters of our model were
obtained from direct measurements inside a car on motorways in Bogot\'a. Next,
we simulated with this model the flux-density fundamental diagram for a
single-lane traffic road and compared it with experimental data. Our
simulations are in very good agreement with the experimental measurements, not
just in the shape of the fundamental diagram, but also in the numerical values
for both the road capacity and the density of maximal flux. Our model
reproduces, too, the qualitative behavior of shock waves. In addition, our work
identifies the periodic boundary conditions as the source of false peaks in the
fundamental diagram, when short roads are simulated, that have been also found
in previous works. The phase transition between free and congested traffic is
also investigated by computing both the relaxation time and the order
parameter. Our work shows how different the traffic behavior from one city to
another can be, and how important is to determine the model parameters for each
city.Comment: 14 pages and 13 figures (gzipped tar file). Submitted to
Int.J.Mod.Phys.C. Minor changes, specially at references and typoes, plus a
clearer summary of the CA rule
Instrumental texture analysis on the surface of dry-cured ham to define the end of the process
The end of the elaboration process of dry-cured ham is currently decided by product weight loss and/or by an expert who carries out an evaluation of the tactile texture on the surface. The objective of this study was to define the optimal measurement conditions of an instrumental texture analysis on the surface of the dry-cured ham (ITAS), to define the end of process. 120 dry-cured hams were classified by experts into Hard (appropriate) or Soft (non-appropriate) texture groups and used to perform compression tests using different probes on three anatomical positions. Results showed that the small probe in position 2 gave the most discriminant conditions, providing representative information of the internal texture. Although classification using only weight loss was possible with an accuracy rate of 80.4 % or 66.7% depending on the weight loss, the maximum classification accuracy was obtained when using ITAS in combination with weight loss. Further studies at industrial level are needed.info:eu-repo/semantics/acceptedVersio
Plasma cytokines as potential biomarkers of kidney damage in patients with systemic lupus erythematosus
Background: Systemic lupus erythematosus is a heterogeneous chronic inflammatory autoimmune
disorder characterized by an exacerbated expression of cytokines and chemokines in
different tissues and organs. Renal involvement is a significant contributor to the morbidity
and mortality of systemic lupus erythematosus, and its diagnosis is based on renal biopsy,
an invasive procedure with a high risk of complications. Therefore, the development of
alternative, non-invasive diagnostic tests for kidney disease in patients with systemic lupus
erythematosus is a priority. Aim: To evaluate the plasma levels of a panel of cytokines and
chemokines using multiplex xMAP technology in a cohort of Colombian patients with active
and inactive systemic lupus erythematosus, and to evaluate their potential as biomarkers of
renal involvement. Results: Plasma from 40 systemic lupus erythematosus non-nephritis
patients and 80 lupus nephritis patients with different levels of renal involvement were analyzed
for 39 cytokines using Luminex xMAP technology. Lupus nephritis patients had significantly
increased plasma eotaxin, TNF-a, interleukin-17-a, interleukin-10, and interleukin-15
as compared to the systemic lupus erythematosus non-nephritis group. Macrophage-derived
chemokine, growth regulated oncogene alpha, and epidermal growth factor were significantly
elevated in systemic lupus erythematosus non-nephritis patients when compared to lupus
nephritis individuals. Plasma eotaxin levels allowed a discrimination between systemic lupus
erythematosus non-nephritis and lupus nephritis patients, for which we performed a receiver
operating characteristic curve to confirm. We observed a correlation of eotaxin levels with
active nephritis (Systemic Lupus Erythematosus Disease Activity Index). Our data indicate
that circulating cytokines and chemokines could be considered good predictors of renal
involvement in individuals with systemic lupus erythematosus
Adiabatic Formation of Rydberg Crystals with Chirped Laser Pulses
Ultracold atomic gases have been used extensively in recent years to realize
textbook examples of condensed matter phenomena. Recently, phase transitions to
ordered structures have been predicted for gases of highly excited, 'frozen'
Rydberg atoms. Such Rydberg crystals are a model for dilute metallic solids
with tunable lattice parameters, and provide access to a wide variety of
fundamental phenomena. We investigate theoretically how such structures can be
created in four distinct cold atomic systems, by using tailored
laser-excitation in the presence of strong Rydberg-Rydberg interactions. We
study in detail the experimental requirements and limitations for these
systems, and characterize the basic properties of small crystalline Rydberg
structures in one, two and three dimensions.Comment: 23 pages, 10 figures, MPIPKS-ITAMP Tandem Workshop, Cold Rydberg
Gases and Ultracold Plasmas (CRYP10), Sept. 6-17, 201
Positive culture in allograft ACL-reconstruction: what to do?
The transmission of disease or infection from the donor to the recipient is always a risk with the use of allografts. We carried out a research study on the behavioural pattern of implanted allografts, which were initially stored in perfect conditions (all cultures being negative) but later presented positive cultures at the implantation stage. Because there is no information available on how to deal with this type of situation, our aim was to set guidelines on the course of action which would be required in such a case. We conducted a retrospective study of 181 patients who underwent an ACL reconstruction using BPTB allografts. All previous bone and blood cultures and tests for hepatitis B and C, syphilis and HIV were negative. An allograft sample was taken for culture in the operating theatre just before its implantation. The results of the cultures were obtained 3-5 days after the operation. We had 24 allografts with positive culture (13.25%) after the implantation with no clinical infection in any of these patients. Positive cultures could be caused by undetected contamination while harvesting, storing or during manipulation before implantation. The lack of clinical signs of infection during the follow-up of our patients may indicate that no specific treatment-other than an antibiotic protocol-would be required when facing a case of positive culture of a graft piece after its implantation
El modelo de auditoria COSO III, para el sector salud en Villavicencio-Meta
The research seeks to deepen the knowledge of accounting and control from an approach to understand the conception of the internal control system used in Pymes. It is essential to recognize the importance of internal control, which in the case of this research is developed with the components of the COSO III model, in the context of the Pymes in the health sector.
The methodology used in the research is developed from a quantitative perspective oriented towards a descriptive approach; the information is obtained and analyzed through checklists and surveys. The purpose of this study is to determine the effectiveness of the internal control implemented in the Pymes of the health sector, from a theoretical approach having as a reference framework the internal control model proposed by COSO III.
Keywords: control, internal audit, SME, accountingLa investigación busca profundizar en el conocimiento de lacontabilidad y control desde una aproximación para conocerla concepción del sistema de control interno empleadoen las Pymes. Es imprescindible reconocer la importanciadel control interno, que para el caso de esta investigación sedesarrolla con los componentes del modelo COSO III, enel contexto de las Pymes del sector salud.La metodología empleada en la investigación, se desarrolladesde una perspectiva cuantitativa orientada hacia unenfoque descriptivo; la información se obtiene y se analizamediante listas de chequeo y encuetas. El propósito deeste estudio es determinar la efectividad del control internoimplementado en las Pymes del sector salud, desde unaaproximación teórica teniendo como marco de referencia elmodelo de control interno propuesto por COSO III
Sentinel Node Detection in Head and Neck Malignancies: Innovations in Radioguided Surgery
Sentinel node mapping is becoming a routine procedure for staging of various malignancies, because it can determine lymph node status more precisely. Due to anatomical problems, localizing sentinel nodes in the head and neck region on the basis of conventional images can be difficult. New diagnostic tools can provide better visualization of sentinel nodes. In an attempt to keep up with possible scientific progress, this article reviews new and innovative tools for sentinel node localization in this specific area.
The overview comprises a short introduction of the sentinel node procedure as well as indications in the head and neck region. Then the results of SPECT/CT for sentinel node detection are described. Finally, a portable gamma camera to enable intraoperative real-time imaging with improved sentinel node detection is described
Comparative study of the indicated cycle of a diesel engine using simulation CFD and experimental data
En este trabajo se presenta un estudio comparativo entre la simulación numérica y datos experimentales del ciclo indicado de un motor diesel de inyección directa. Para esto se han efectuado una simulación multidimensional utilizando un paquete CFD y empleando un modelo predictivo, para varias condiciones de operación del motor. Ambos resultados se han comparado con datos experimentales medidos sobre un motor montado en banco de ensayos. El estudio se ha hecho en términos de los parámetros habituales del ciclo indicado como la evolución temporal de presión, temperatura y calor liberado, así como de la potencia, efciencia, consumo específco de combustible y presión media indicada.
Los resultados muestran que las curvas de presiones simuladas son bastante próximas a las medidas en todos los casos analizados, con las mayores diferencias en los modos de baja carga en torno a un 5% como mucho en el pico de máxima presión, aunque si se encuentran diferencias en las curvas de temperatura y de tasa de calor liberado, debido en parte a la calidad de los modelos de combustión y transferencia de calor empleados en la simulación. No obstante, queda demostrada la conveniencia del uso de herramientas basadas en CFD aplicadas al estudio de la combustión en motores.In this paper, a comparative study between numerical simulations and experimental data of the indicated cycle of a direct injection diesel engine is presented. A CFD package and a predictive model were used to simulate several engine operating conditions. Results were compared with experimental data obtained from an engine test bench. The comparison was based on indicated-cycle parameters such as pressure, temperature, heat release, power, effciency, specifc fuel consumption and mean effective pressure. Results show that in all cases simulated cylinder-pressure curves are in very good agreement with the experimental results. For the low-load mode, differences are around 5% at maximum pressure peak. On the other hand, temperature and heat release rate curves present signifcant differences between simulations and experiments. This could be a consequence of the combustion and heat transfer models used for the simulations. However, it is shown that the use of CFD tools for studying combustion phenomena in diesel engines is highly convenient
- …