Méthode numérique appliquée aux modèles analogiques quantifiables

La dinámica molecular de los polímeros puede explicarse utilizando sistemas construidos a partir de muelles y émbolos. Uno de los modelos más sustentables es el modelo de Vangheluwe y sus constantes paramétricas se determinan por los métodos método gráfico, método iterativo Marquardt, método del hiperplano. Así mismo otro modelo importante es el modelo de Zurek que determina sus constantes paramétricas usando un método gráfico e iterativo Marquardt. En este trabajo se aplica la técnica de mínimos cuadrados para evaluar las constantes numéricas de ambos modelos. La tecnica de mínimos cuadrados conduce a un sistema de ecuaciones no lineales que se resolvió por el método de Newton-Raphson. El resultado en ambos modelos fue sensiblemente mejor a los métodos disponibles.The molecular dynamics of polymers can be explained by means of systems constructed on the bases of springs and pistons. One of the most valid models is the Vangheluwe model and its parametric constants are determined by the graphic method1, the Marquardt iterative method, and the hyperplane method. Another important model is the Zurek model, whose parametric constants are determined using a graphic method and the iterative Marquardt method. In this paper, we apply the least squares technique to evaluate the numerical constants of both models. The least squares technique leads to a system of non-linear equations that were solved using the Newton-Raphson method. The results of both models were noticeably better than the available methods.La dynamique moléculaire des polymères peut s'expliquer en utilisant des systèmes construits avec des ressorts et des pistons. L'un des modèles les plus abordables est celiu de Vangheluwe et ses constantes paramétriques sont déterminées par les méthodes suivantes: méthode graphique, méthode itérative Marquardt, méthode de l'hyperplan. De même, un autre modèle important est celiu de Zurek qui détermine ses constantes paramétriques en utilisant une méhtode graphique et itérative Marquardt. Dans cette étude, la méthode des minimums carrés a été appliquée pour évaluer les constantes numériques des deux modèles. La technique des minimums carrés conduit à un système d'équations non linéaires qui est résolu par la méthode de Newton-Raphson. Dans les deux cas, le résultat a été sensiblement meilleur que celiu des méthodes disponibles

Individual Variations in Maternal Care Early in Life Correlate with Later Life Decision-Making and c-Fos Expression in Prefrontal Subregions of Rats

Early life adversity affects hypothalamus-pituitary-adrenal axis activity, alters cognitive functioning and in humans is thought to increase the vulnerability to psychopathology–e.g. depression, anxiety and schizophrenia- later in life. Here we investigated whether subtle natural variations among individual rat pups in the amount of maternal care received, i.e. differences in the amount of licking and grooming (LG), correlate with anxiety and prefrontal cortex-dependent behavior in young adulthood. Therefore, we examined the correlation between LG received during the first postnatal week and later behavior in the elevated plus maze and in decision-making processes using a rodent version of the Iowa Gambling Task (rIGT). In our cohort of male and female animals a high degree of LG correlated with less anxiety in the elevated plus maze and more advantageous choices during the last 10 trials of the rIGT. In tissue collected 2 hrs after completion of the task, the correlation between LG and c-fos expression (a marker of neuronal activity) was established in structures important for IGT performance. Negative correlations existed between rIGT performance and c-fos expression in the lateral orbitofrontal cortex, prelimbic cortex, infralimbic cortex and insular cortex. The insular cortex correlations between c-fos expression and decision-making performance depended on LG background; this was also true for the lateral orbitofrontal cortex in female rats. Dendritic complexity of insular or infralimbic pyramidal neurons did not or weakly correlate with LG background. We conclude that natural variations in maternal care received by pups may significantly contribute to later-life decision-making and activity of underlying brain structures

Why Are Outcomes Different for Registry Patients Enrolled Prospectively and Retrospectively? Insights from the Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF).

Background: Retrospective and prospective observational studies are designed to reflect real-world evidence on clinical practice, but can yield conflicting results. The GARFIELD-AF Registry includes both methods of enrolment and allows analysis of differences in patient characteristics and outcomes that may result. Methods and Results: Patients with atrial fibrillation (AF) and ≥1 risk factor for stroke at diagnosis of AF were recruited either retrospectively (n = 5069) or prospectively (n = 5501) from 19 countries and then followed prospectively. The retrospectively enrolled cohort comprised patients with established AF (for a least 6, and up to 24 months before enrolment), who were identified retrospectively (and baseline and partial follow-up data were collected from the emedical records) and then followed prospectively between 0-18 months (such that the total time of follow-up was 24 months; data collection Dec-2009 and Oct-2010). In the prospectively enrolled cohort, patients with newly diagnosed AF (≤6 weeks after diagnosis) were recruited between Mar-2010 and Oct-2011 and were followed for 24 months after enrolment. Differences between the cohorts were observed in clinical characteristics, including type of AF, stroke prevention strategies, and event rates. More patients in the retrospectively identified cohort received vitamin K antagonists (62.1% vs. 53.2%) and fewer received non-vitamin K oral anticoagulants (1.8% vs . 4.2%). All-cause mortality rates per 100 person-years during the prospective follow-up (starting the first study visit up to 1 year) were significantly lower in the retrospective than prospectively identified cohort (3.04 [95% CI 2.51 to 3.67] vs . 4.05 [95% CI 3.53 to 4.63]; p = 0.016). Conclusions: Interpretations of data from registries that aim to evaluate the characteristics and outcomes of patients with AF must take account of differences in registry design and the impact of recall bias and survivorship bias that is incurred with retrospective enrolment. Clinical Trial Registration: - URL: http://www.clinicaltrials.gov . Unique identifier for GARFIELD-AF (NCT01090362)

Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.

BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

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Méthode numérique appliquée aux modèles analogiques quantifiables

La dinámica molecular de los polímeros puede explicarse utilizando sistemas construidos a partir de muelles y émbolos. Uno de los modelos más sustentables es el modelo de Vangheluwe y sus constantes paramétricas se determinan por los métodos método gráfico, método iterativo Marquardt, método del hiperplano. Así mismo otro modelo importante es el modelo de Zurek que determina sus constantes paramétricas usando un método gráfico e iterativo Marquardt. En este trabajo se aplica la técnica de mínimos cuadrados para evaluar las constantes numéricas de ambos modelos. La tecnica de mínimos cuadrados conduce a un sistema de ecuaciones no lineales que se resolvió por el método de Newton-Raphson. El resultado en ambos modelos fue sensiblemente mejor a los métodos disponibles.The molecular dynamics of polymers can be explained by means of systems constructed on the bases of springs and pistons. One of the most valid models is the Vangheluwe model and its parametric constants are determined by the graphic method1, the Marquardt iterative method, and the hyperplane method. Another important model is the Zurek model, whose parametric constants are determined using a graphic method and the iterative Marquardt method. In this paper, we apply the least squares technique to evaluate the numerical constants of both models. The least squares technique leads to a system of non-linear equations that were solved using the Newton-Raphson method. The results of both models were noticeably better than the available methods.La dynamique moléculaire des polymères peut s'expliquer en utilisant des systèmes construits avec des ressorts et des pistons. L'un des modèles les plus abordables est celiu de Vangheluwe et ses constantes paramétriques sont déterminées par les méthodes suivantes: méthode graphique, méthode itérative Marquardt, méthode de l'hyperplan. De même, un autre modèle important est celiu de Zurek qui détermine ses constantes paramétriques en utilisant une méhtode graphique et itérative Marquardt. Dans cette étude, la méthode des minimums carrés a été appliquée pour évaluer les constantes numériques des deux modèles. La technique des minimums carrés conduit à un système d'équations non linéaires qui est résolu par la méthode de Newton-Raphson. Dans les deux cas, le résultat a été sensiblement meilleur que celiu des méthodes disponibles

Neonatal exposure to monosodium glutamate disrupts place learning ability in adult rats

The activation of glutamatergic NMDA receptors of the hippocampus is closely associated with expression of place learning. Neonatal exposure to monosodium glutamate leads to abnormal expression of NMDA receptor subunits in the hippocampus, but its effect on place learning is unknown. Place learning acquisition and retrieval were assessed in mature adult rats after subcutaneous injection of monosodium glutamate (4 mg/g body weight) in eight neonatal rat pups at postnatal days one, three, five, and seven. Eight untreated rats were used as controls. At four months of age, the rats were challenged over a period of nine days with a place learning task. The task used an acquisition-retrieval paradigm in a Morris maze. Place learning acquisition was impaired in the experimental rats, which were unable to reduce their escape latencies during the nine training days. Controls improved between the fifth and ninth days of training. Test trials showed that retrieval of spatial information was also impaired in the experimental animals. These results show that both place learning acquisition and retrieval abilities in mature rats are impaired by neonatal treatment with monosodium glutamate. These findings may be related to the abnormal expression of NMDA receptor subunits in the hippocampus. © 2005 Elsevier Inc. All rights reserved

Cerebral serotonin depletion induces egocentric learning improvement in developing rats

Egocentric learning ability of developing serotonin (5-HT)-depleted female rats was evaluated in the Morris maze test. 5-HT depletion was accomplished by a unique intracisternal injection of 5,7-dihydroxytriptamine at 21 days-old. A first behavioral test was applied before the lesion procedure. The animals were thereafter challenged to resolve the same test at 40 and 60 days-old. 5-HT depletion caused a dual effect on the rats' egocentric learning ability, i.e. at 40 days; control rats learned the task while the experimental rats were unable to learn it. At 60 days, control animals were unable to learn the test, while the experimental rats showed a successful performance. These results strongly suggest that 5-HT neurotransmission is necessary for egocentric learning establishment and regulation. Zapotitlán 2001 Published by Elsevier Science Ireland Ltd

Método numérico aplicado a los modelos analógicos cuantificables (para polímeros)

La dynamique moléculaire des polymères peut s'expliquer en utilisant des systèmes construits avec des ressorts et des pistons. L'un des modèles les plus abordables est celiu de Vangheluwe et ses constantes paramétriques sont déterminées par les méthodes suivantes: méthode graphique, méthode itérative Marquardt, méthode de l'hyperplan. De même, un autre modèle important est celiu de Zurek qui détermine ses constantes paramétriques en utilisant une méhtode graphique et itérative Marquardt. Dans cette étude, la méthode des minimums carrés a été appliquée pour évaluer les constantes numériques des deux modèles. La technique des minimums carrés conduit à un système d'équations non linéaires qui est résolu par la méthode de Newton-Raphson. Dans les deux cas, le résultat a été sensiblement meilleur que celiu des méthodes disponibles