ABSTRACT
The classical three-body harmonic system in [Formula: see text] ([Formula: see text]) with finite rest lengths and zero total angular momentum [Formula: see text] is considered. This model describes the dynamics of the [Formula: see text] near-equilibrium configurations of three point masses [Formula: see text] with arbitrary pairwise potential [Formula: see text] that solely depends on the relative distances between bodies. It exhibits an interesting mixed regular and chaotic dynamics as a function of the energy and the system parameters. The corresponding harmonic quantum system plays a fundamental role in atomic and molecular physics. In this work we report on a novel electronic experimental realization of the model as a complementary tool to analyze the rich dynamics of the classical system. Our setup allows us to experimentally explore different regions of behavior due to the fact that the intrinsic parameters and initial states of the system are independently set by voltage inputs. Chaotic and periodic motions are characterized employing time series, phase planes, and the largest Lyapunov exponents as a function of the energy and system parameters. The results show an excellent qualitative as well as quantitative agreement between theory and experiment.
ABSTRACT
We propose a model to generate electrocardiogram signals based on a discretized reaction-diffusion system to produce a set of three nonlinear oscillators that simulate the main pacemakers in the heart. The model reproduces electrocardiograms from healthy hearts and from patients suffering various well-known rhythm disorders. In particular, it is shown that under ventricular fibrillation, the electrocardiogram signal is chaotic and the transition from sinus rhythm to chaos is consistent with the Ruelle-Takens-Newhouse route to chaos, as experimental studies indicate. The proposed model constitutes a useful tool for research, medical education, and clinical testing purposes. An electronic device based on the model was built for these purposes.
Subject(s)
Electrocardiography , Models, Cardiovascular , Signal Processing, Computer-Assisted , Arrhythmias, Cardiac/diagnostic imaging , Computer Simulation , Diffusion , Nonlinear Dynamics , Numerical Analysis, Computer-Assisted , Time Factors , Ventricular Fibrillation/diagnostic imagingABSTRACT
We propose a simple model of the electrical activity of the heart that reproduces realistic healthy electrocardiogram (ECG) signals. The model consists of two RLC linear oscillators periodically kicked by impulses of the main pacemaker with the frequency rate of a real heart. In the proposed model, one oscillator represents the atria, another represents the ventricles, and an electrical cardiac conduction system is included using a coupling capacitor, which can be either unidirectional or bidirectional. The network of the two capacitively coupled oscillators is periodically kicked by the main pacemaker to introduce the periodic forcing of limit cycles into the system; a time delay is introduced to represent the electrical transport delay from atria to ventricles. In this manner, healthy synthetic ECG signals are obtained by combining the signals of the currents of the oscillators. We show that an analytical solution of the model can be obtained when a single impulse is applied. From this, by the superposition principle, a solution with an impulse train is obtained. Note that analytical treatment is a feature not available in current cardiac oscillator models.
Subject(s)
Action Potentials , Biological Clocks , Electrocardiography , Heart Conduction System/physiopathology , Models, Cardiovascular , HumansABSTRACT
RESUMEN: En este trabajo se presenta un método para medir densidad ósea. El método consiste en la medición de conductividad eléctrica de material óseo por medio de Tomografía de Impedancia Eléctrica (TIE). Se hace uso de una celda de prueba con valores simulados de hueso aplicando corrientes y registrando voltajes, para después usar una reconstrucción por retroproyección y generar mapas de conductividad por medio de gráficas. Los datos obtenidos son analizados y a partir de ellos se obtiene una distribución de la medida de conductividad eléctrica del material óseo, que varía dependiendo del grado de porosidad que presenta en cada región. La ventaja de utilizar el método de tomografía de impedancia es que permite medir la conductividad efectiva del hueso porque se mide en todas las direcciones. Por lo tanto es posible determinar porosidad en material óseo usando mediciones de conductividad eléctrica por medio del método TIE propuesto, lo cual permite calcular un valor numérico de densidad ósea.
ABSTRACT: In this paper a method to measure bone density was developed. The method consists in the measurement of electrical conductivity of bone by Electrical Impedance Tomography (EIT). A phantom with simulated data of bone is used, applying currents and recording voltages; then a backprojection reconstruction is used to generate maps with graphic conductivity values. The data obtained were analyzed and was obtained a distribution of electrical conduc tivity of bone, wich varies according to the bone porosity level in each region. A significant advantage of using this method is that is possible to measure electrical conductivity in several directions of the bone, obtaining an effective conductivity. Therefore it is possible to determine the porosity in the bone with measurements of electrical conductivity using the proposed EIT method, this allows to calculate a numerical value for bone density.
ABSTRACT
No disponible
Subject(s)
Humans , Aneurysm, False/etiology , Wounds, Penetrating/complications , Arteriovenous Fistula/etiology , Femoral Artery/injuriesABSTRACT
OBJECTIVE: To determine whether there is an association between the Primary Nursing Model and perceived quality of care. METHOD: An observational, descriptive, cross-sectional study in four hospital wards with Primary Nursing organization. Over a 12-month period, all the patients discharged from each ward were included in this study. The degree of development of Primary Nursing was measured by using the Personalization of Nursing Care Index and the perceived quality of care was measured with the LOPSS-12. Bivariate statistical analysis was carried out through ANOVA and Student's t-tests. Multivariate linear regression analysis was then applied to correlated variables (p < 0.05). RESULTS: 817 patients were included, 447 from two medical wards and 370 from two surgical wards. After a preliminary data analysis performed 6 months after the start of the study, four items were removed from the LOPSS-12 and each of the remaining items were analyzed separately. Scores for both patient satisfaction and the introduction of the Primary Nursing Model were higher in the surgical wards. Bivariate and multivariate regression analyses showed a statistically significant (p < 0.05) association between implantation of the model and all except one of the items included in the questionnaire. CONCLUSIONS: The introduction of the Primary Nursing Model in hospital wards allows the presence of a primary nurse for each patient and consequently improves the nurse-patient relationship, increasing perceived quality of care among patients.
Subject(s)
Hospital Departments/organization & administration , Patient Satisfaction , Precision Medicine/nursing , Primary Nursing/organization & administration , Quality of Health Care , Adult , Aged , Cross-Sectional Studies , Female , Humans , Internal Medicine/organization & administration , Male , Middle Aged , Models, Theoretical , Nurse-Patient Relations , Patients' Rooms/organization & administration , Precision Medicine/psychology , Primary Nursing/standards , Social Perception , Surgery Department, Hospital/organization & administration , Surveys and QuestionnairesABSTRACT
MOTIVATION: Gene expression measurements are the most common data source for reverse engineering gene interaction networks. When dealing with destructive sampling in time course experiments, it is common to average any available measurements for each time point and to treat this as the actual time series data for fitting the network, neglecting the variability contained in the repeated measurements. Proceeding in such a way can affect the retrieved network topology. RESULTS: We propose a fully Bayesian method for reverse engineering a gene interaction network, based on time course data with repeated measurements. The observations are treated as surrogate measurements of the underlying gene expression. As these measurements often contain outliers, we use a non-Gaussian specification for dealing with measurement error. The network interactions are assumed linear and an autoregressive model is specified, augmented with indicator variables that allow inference on the topology of the network. We analyse two in silico and one in vivo experiments, the latter dealing with the circadian clock in Arabidopsis thaliana. A systematic attenuation of the estimated regulation strengths and a concomitant overestimation of their precision is demonstrated when measurement error is disregarded. Thus, a clear improvement in the inferred topology for the synthetic datasets is demonstrated when this is included. Also, the influence of outliers in the retrieved network is demonstrated when using the in vivo data. AVAILABILITY: Matlab code and data used in the article are available from http://go.warwick.ac.uk/majuarez/home/materials.
Subject(s)
Gene Regulatory Networks , Algorithms , Arabidopsis/physiology , Bayes Theorem , Circadian Rhythm , Computer Simulation , Gene Expression Profiling , Models, Genetic , UncertaintyABSTRACT
Se presenta una paciente de 49 años de edad,con Sindrome de Piccardi-Graham-Little-Lassueur.Tenia una alopecia cicatrizal de cuero cabelludo,alopecia transitoria de axilas y pubis y liquen plano fulicular en piel.Este sindrome asociado con alteraciones psicologicas,menospausia reciente y hepatitis severa.Evoluciono favorablemente con tratamiento conservador.AU
Subject(s)
Humans , Female , Middle Aged , Alopecia/diagnosis , Alopecia/pathology , Alopecia/therapy , Scalp Dermatoses/physiopathology , Lichen Planus/diagnosis , Pubic Bone , Axilla , PruritusABSTRACT
Se presenta una paciente de 49 años de edad,con Sindrome de Piccardi-Graham-Little-Lassueur.Tenia una alopecia cicatrizal de cuero cabelludo,alopecia transitoria de axilas y pubis y liquen plano fulicular en piel.Este sindrome asociado con alteraciones psicologicas,menospausia reciente y hepatitis severa.Evoluciono favorablemente con tratamiento conservador.
Subject(s)
Humans , Female , Middle Aged , Alopecia/diagnosis , Alopecia/pathology , Alopecia/therapy , Lichen Planus/diagnosis , Scalp Dermatoses/physiopathology , Axilla , Pruritus , Pubic BoneABSTRACT
Fifteen spindle cell carcinomas, 9 from the larynx, 4 from skin, 1 from pharynx and 1 from the esophagus were studied with a variety of mesenchymal and epithelial markers: vimentin (VIM), smooth muscle actin (ACT), desmin (DESM), cytokeratin (AE1), polyclonal keratin (Q), and epithelial membrane antigen (EMA). Peroxidase-antiperoxidase and avidin-biotin complex techniques were used. Ten of the lesions were biphasic and the remaining 5 monophasic, showing only the spindle cell component. The spindle cell areas were positive for ACT (14/15), VIM (13/15), DESM (10/15), Q (10/15), AEi (14/15) and EMA (3/15). There were 12 cases in which the spindle cell component was stained with epithelial and mesenchymal markers. Areas of squamous cell carcinoma were positive with the epithelial markers and unstained with the mesenchymal markers. These results support the concept of a bidirectional differentiation in the pathogenesis of these lesions with a "mesenchymal" metaplasia of malignant epithelial cells.
Subject(s)
Biomarkers, Tumor/analysis , Carcinoma/pathology , Esophageal Neoplasms/pathology , Humans , Immunohistochemistry , Laryngeal Neoplasms/pathology , Pharyngeal Neoplasms/pathology , Skin Neoplasms/pathologyABSTRACT
Fifteen spindle cell carcinomas, 9 from the larynx, 4 from skin, 1 from pharynx and 1 from the esophagus were studied with a variety of mesenchymal and epithelial markers: vimentin (VIM), smooth muscle actin (ACT), desmin (DESM), cytokeratin (AE1), polyclonal keratin (Q), and epithelial membrane antigen (EMA). Peroxidase-antiperoxidase and avidin-biotin complex techniques were used. Ten of the lesions were biphasic and the remaining 5 monophasic, showing only the spindle cell component. The spindle cell areas were positive for ACT (14/15), VIM (13/15), DESM (10/15), Q (10/15), AEi (14/15) and EMA (3/15). There were 12 cases in which the spindle cell component was stained with epithelial and mesenchymal markers. Areas of squamous cell carcinoma were positive with the epithelial markers and unstained with the mesenchymal markers. These results support the concept of a bidirectional differentiation in the pathogenesis of these lesions with a [quot ]mesenchymal[quot ] metaplasia of malignant epithelial cells.
ABSTRACT
Se da a conocer el hallazgo en la provincia de Catamarca, Republica Argentina, de trece casos de lepra diagnosticados entre octubre de 1980 y noviembre de 1983. Como geograficamente no es zona endemica de lepra, se considera de gran importancia epidemiologica el diagnostico de estos trece enfermos ya que son los primeros oficialmente notificados y registrados por las autoridades de salud publica de la ciudad de Catamarca. Fueron estudiados mediante examen clinico-dermatologico, histopatologia, baciloscopia e inmunologia, con controles periodicos en su evolucion y tratamiento. Al efectuar el control de convivientes no se pudo demostrar origen foraneo de contagio, por lo cual deben ser considerados verdaderos casos autoctonos
Subject(s)
Humans , Leprosy , ArgentinaABSTRACT
Se da a conocer el hallazgo en la provincia de Catamarca, Republica Argentina, de trece casos de lepra diagnosticados entre octubre de 1980 y noviembre de 1983. Como geograficamente no es zona endemica de lepra, se considera de gran importancia epidemiologica el diagnostico de estos trece enfermos ya que son los primeros oficialmente notificados y registrados por las autoridades de salud publica de la ciudad de Catamarca. Fueron estudiados mediante examen clinico-dermatologico, histopatologia, baciloscopia e inmunologia, con controles periodicos en su evolucion y tratamiento. Al efectuar el control de convivientes no se pudo demostrar origen foraneo de contagio, por lo cual deben ser considerados verdaderos casos autoctonos
Subject(s)
Humans , Leprosy , ArgentinaABSTRACT
Se efectuo la determinacion histoquimica de receptores estrogenicos en 48 carcinomas mamarios usando un conjugado de 17Bestradiol con isotiocianato de fluoresceina que producia una fluorescencia citoplasmatica en las celulas positivas. Se demostro que todos los carcinomas mamarios estan compuestos por una mezcla en proporciones variables de celulas positivas y negativas para receptores estrogenicos. Utilizando criterios semicuantitativos, se consideraron a 23 de los 48 casos, como positivos. En el grupo positivo pero no en el negativo, la correlacion con los receptores estrogenicos dosados por la tecnica bioquimica fue excelente. El metodo histoquimico fue tambien aplicado a material citologico y al dosaje de receptores de progesterona con exito
Subject(s)
Humans , Female , Breast Neoplasms , Receptors, Estrogen , HistocytochemistryABSTRACT
Se efectuo la determinacion histoquimica de receptores estrogenicos en 48 carcinomas mamarios usando un conjugado de 17Bestradiol con isotiocianato de fluoresceina que producia una fluorescencia citoplasmatica en las celulas positivas. Se demostro que todos los carcinomas mamarios estan compuestos por una mezcla en proporciones variables de celulas positivas y negativas para receptores estrogenicos. Utilizando criterios semicuantitativos, se consideraron a 23 de los 48 casos, como positivos. En el grupo positivo pero no en el negativo, la correlacion con los receptores estrogenicos dosados por la tecnica bioquimica fue excelente. El metodo histoquimico fue tambien aplicado a material citologico y al dosaje de receptores de progesterona con exito
Subject(s)
Humans , Female , Breast Neoplasms , Receptors, Estrogen , HistocytochemistryABSTRACT
A la bibliografia nacional se agregan 8 enfermos que presentaron quistes serosos del higado: 4 presentaron cuadros abdominales agudos, algunos concomitantes a complicaciones por litiasis biliar. Los otros 4 presentaron tumores palpables en el hipocondrio derecho. Todos los enfermos fueron operados, practicandose 2 quistectomias totales y en los demas, resecciones parciales. Un enfermo fallecio en el postoperatorio inmediato por sepsis; 1 fallecio a los 5 anos por un cuadro de sepsis con ictericia que no fue reoperado; 1 tuvo que ser reoperado a los 2 anos por recidiva. Los demas permanecen curados luego de la primera intervencion. Se presenta un analisis sobre los caracteres anatomopatologicos y la etiopatogenia disembrioplasica de los quistes serosos del higado
Subject(s)
Adult , Middle Aged , Aged , Humans , Male , Female , Cysts , Liver DiseasesABSTRACT
A la bibliografia nacional se agregan 8 enfermos que presentaron quistes serosos del higado: 4 presentaron cuadros abdominales agudos, algunos concomitantes a complicaciones por litiasis biliar. Los otros 4 presentaron tumores palpables en el hipocondrio derecho. Todos los enfermos fueron operados, practicandose 2 quistectomias totales y en los demas, resecciones parciales. Un enfermo fallecio en el postoperatorio inmediato por sepsis; 1 fallecio a los 5 anos por un cuadro de sepsis con ictericia que no fue reoperado; 1 tuvo que ser reoperado a los 2 anos por recidiva. Los demas permanecen curados luego de la primera intervencion. Se presenta un analisis sobre los caracteres anatomopatologicos y la etiopatogenia disembrioplasica de los quistes serosos del higado
