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Modificaciones Hemodinámicas Asociadas a la Asimetría de Aneurismas de Aorta Abdominal y su Influencia en las Posibilidades de Ruptura
Nieto,Félix; Vilalta,Guillermo; Peréz,María á; Lipsa,Laurentiu M;
Información tecnológica , 2012, DOI: 10.4067/S0718-07642012000300017
Abstract: influence of abdominal aortic aneurysms asymmetry on the hemodynamics within the aneurysmatic sac is analyzed and its influence on the rupture potential is discussed. a numerical study by using four idealized geometric models, with different asymmetry degrees, is carried out. blood is modelled as a newtonian, homogeneous, incompressible and laminar flow with properties as typically used in the literature. the results showed that the flow inside of the aneurysmatic sac is highly disturbed with intense vortex structures travelling from proximal to distal ends, strongly influencing on the wall shear stress distribution. it have also been established that, despite that the aneurysm are asymmetric, this factor has low weight on aneurysm rupture.
Hemodynamic of abdominal aortic aneurysm (AAA) and morphometryc characterization as a possible indicator of rupture Hemodinámica de aneurismas de aorta abdominal (AAA) y caracterización morfométrica como posible indicador de ruptura
Guillermo Vilalta Alonso,Félix Nieto Palomo,Melchor Rodríguez Madrigal,Laurentiu Lipsa
Revista Cubana de Ingeniería , 2010, DOI: 10.1234/rci.v1i3.25
Abstract: The rupture of abdominal aortic aneurysm (AAA) represents an important clinical event combining structural modifications that provoke a weakening of the arterial wall, coupled with the hemodynamic pressure acting on them. In an effort to increase understanding about this complex phenomenon, this paper studies the influence of abdominal aortic aneurysm asymmetry in the patterns of the main hemodynamics factors. Flow simulation in four 3D virtual AAA models with different asymmetry ranging from 0.2 to 0.8 were carried out under realistic pulsatile conditions to assess and identify regions with disturbed patterns flow and how it modifies the velocities fields and hemodynamic stress on the inside of the aneurysmatic sac. An explanation of the vortex structure changes and stress distribution during cardiac pulse, it is presented. The results obtained shown that the asymmetry is one of the main factors that influence the AAA rupture. On the other hand, the basis to establish a novel method, based on the morphometry of the AAA, to determine a numerical indicator characterizing the evolution and the rupture risk of aneurysm, regardless of size, it is approached. It is outlined the initial results of the validation, its current limitations and the future steps to improve the method. La ruptura de aneurismas de aorta abdominal (AAA) representan un evento clínico muy importante resultante de las modificaciones estructurales de la pared arterial que provocan un debilitamiento de la pared arterial combinadas con las presiones hemodinámicas que actúan sobre esta. En un esfuerzo por aumentar la comprensión sobre este complejo fenómeno, en el presente trabajo se estudia la influencia del grado de asimetría de los aneurismas de aorta abdominal, en los patrones de comportamiento de los principales factores hemodinámicos. Para esto, se han evaluado 4 modelos geométricos no realistas de AAA con diferentes grados de asimetría, sometidos a un flujo pulsatil fisiológicamente realista, con el objetivo de evaluar e identificar las regiones donde ocurren las principales perturbaciones en los patrones de flujo y como ésta modifica los campos de velocidades y de tensiones hemodinámicas, en el interior del saco aneurismático. Se presenta una explicación de las modificaciones de las estructuras vorticales y de la distribución de tensiones durante el ciclo cardíaco, cuyos resultados confirman que la asimetría de los aneurismas de aorta abdominal es uno de los principales factores que influyen en su ruptura. Por otro lado, en el trabajo se abordan las bases para establecer un método
Modificaciones Hemodinámicas Asociadas a la Asimetría de Aneurismas de Aorta Abdominal y su Influencia en las Posibilidades de Ruptura Hemodynamic Modifications Associated to Abdominal Aortic Aneurysm Asymmetry and its Influence on Rupture Potential
Félix Nieto,Guillermo Vilalta,María á Peréz,Laurentiu M Lipsa
Información Tecnológica , 2012,
Abstract: Se analiza la influencia de la asimetría de los aneurismas de aorta abdominal en la dinámica del flujo sanguíneo en el interior del saco aneurismático y se discute cómo este comportamiento puede influir en el potencial de ruptura de los aneurismas. Para ello se realiza un estudio numérico empleando cuatro modelos geométricos idealizados con diferente grado de asimetría. La sangre es modelada como Newtoniana, homogénea, incompresible y laminar con propiedades semejantes a los valores que típicamente se emplean en la literatura. Los resultados mostraron que el flujo en el interior del saco aneurismático es altamente perturbado con intensas estructuras de vórtices que viajan desde el extremo proximal al distal, ejerciendo una gran influencia en la distribución superficial de las tensiones tangenciales. También se ha establecido que, a pesar que los aneurismas son asimétricos, este factor tiene un peso ponderado bajo en las posibilidades de ruptura de los aneurismas. Influence of abdominal aortic aneurysms asymmetry on the hemodynamics within the aneurysmatic sac is analyzed and its influence on the rupture potential is discussed. A numerical study by using four idealized geometric models, with different asymmetry degrees, is carried out. Blood is modelled as a newtonian, homogeneous, incompressible and laminar flow with properties as typically used in the literature. The results showed that the flow inside of the aneurysmatic sac is highly disturbed with intense vortex structures travelling from proximal to distal ends, strongly influencing on the wall shear stress distribution. It have also been established that, despite that the aneurysm are asymmetric, this factor has low weight on aneurysm rupture.
Ruptura de aneurismas de aorta abdominal. Herramienta informática para su predicción
Vilalta-Alonso,Guillermo; Nieto,Félix; Vilalta-Alonso,José A.; Vaquero,Carlos; Lipsa,Laurentiu M.; Rodríguez-Madrigal,Melchor;
Ingenier?-a Mec??nica , 2011,
Abstract: the rupture of abdominal aortic aneurysm (aaa) represents an important clinical event due to its high mortality rate. currently the criteria to decide on the treatment of aaa patients are the peak transverse diameter and the growth rate which can be considered insufficient because they have not a reasonable physical base. the foundations for the design of pc software to predict, with sufficient accuracy to be clinically relevant, the risk of aaa rupture on patient-specific basis are defined in this paper. the software consists of 3 modules which are designed for processing all patient-specific information and integrate them through a model that interrelates the different nature (biological, structural and geometric) and scales (temporal and dimensional) biomechanical factors, in order to calculate a numerical and patient-specific indicator of the rupture risk. this tool should be an auxiliary element to physician in making decision on appropriate treatment decisions for patients with aneurysm.
ESTIMATION OF PHILLIPS CURVE IN INDIAN CONTEXT
LIPSA RAY
International Journal of Economics and Research , 2012,
Abstract: This paper revisits the empirical existence of the Phillips curve in the Indian context. To estimate the Phillips curve we need two variables – inflation and the output gap. In the case of India, incorrect measurement of both variables causes much difficulty in estimating the Phillips curve. I have used Hodrick-Prescott filter approach to find the output gap, ARMA (1) model for expected inflation and finally, used Generalized Method of Moment estimation to estimate the Phillips curve in Indian context. My result shows that the tradeoff between inflation and growth is positive in India during the period of 1970 to 2010. Moreover, I also found that there is no long run relationship between the variables viz; inflation, expected inflation and output gap .Because all the variables are stationary at their original level, which proved that Phillips curve only in short run, not in long run. In long run, it is vertical
Data Mining: A Tool for Knowledge Management in Human Resource
Ms. Lipsa Sadath
International Journal of Innovative Technology and Exploring Engineering , 2013,
Abstract: Competitiveness is a company’s ability to maintain gain and reputation in its respective market or industry. Human Resource Management (HRM) plays a lead role in determining this competitiveness and effectiveness for better survival. The HRM generally refers to the policies, practices and systems influencing employee behavior, attitude and performance. Companies consider HRM as “people practices”. So it becomes the responsibility of the HRM to mine the best talents at the right time, train them, observe their performance, reward them and ultimately keep them happy in a company. It is simply because of the reason that every strategy of an organization is directly or indirectly related to the talents of the same. To gain and sustain a competitive advantage, knowledge management (developing, sharing and applying knowledge) within the organization becomes essential. But then how is HRM connected to Knowledge Management (KM) becomes a very relevant question. When employees are evaluated from their performance, different methods can be used for mining the best knowledge out of them. This paper is an attempt to study and understand the potential of Data Mining (DM) techniques for automated intelligent decisions from rich employee data base for predictions of employee performance implementing the finest KM strategies, thus achieving stable HR system and brilliant business.
Molecular Basis of Differential Selectivity of Cyclobutyl-Substituted Imidazole Inhibitors against CDKs: Insights for Rational Drug Design
Soumya Lipsa Rath, Sanjib Senapati
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0073836
Abstract: Cyclin-dependent kinases (CDKs) belong to the CMGC subfamily of protein kinases and play crucial roles in eukaryotic cell division cycle. At least seven different CDKs have been reported to be implicated in the cell cycle regulation in vertebrates. These CDKs are highly homologous and contain a conserved catalytic core. This makes the design of inhibitors specific for a particular CDK difficult. There is, however, growing need for CDK5 specific inhibitors to treat various neurodegenerative diseases. Recently, cis-substituted cyclobutyl-4-aminoimidazole inhibitors have been identified as potent CDK5 inhibitors that gave up to 30-fold selectivity over CDK2. Available IC50 values also indicate a higher potency of this class of inhibitors over commercially available drugs, such as roscovitine. To understand the molecular basis of higher potency and selectivity of these inhibitors, here, we present molecular dynamics simulation results of CDK5/p25 and CDK2/CyclinE complexed with a series of cyclobutyl-substituted imidazole inhibitors and roscovitine. The atomic details of the stereospecificity and selectivity of these inhibitors are obtained from energetics and binding characteristics to the CDK binding pocket. The study not only complements the experimental findings, but also provides a wealth of detailed information that could help the structure-based drug designing processes.
Time for pulse traversal through slabs of dispersive and negative ($ε$, $μ$) materials
Lipsa Nanda,S. Anantha Ramakrishna
Physics , 2007, DOI: 10.1103/PhysRevA.76.063807
Abstract: The traversal times for an electromagnetic pulse traversing a slab of dispersive and dissipative material with negative dielectric permittivity ($\epsilon$) and magnetic permeability ($\mu$) have been calculated by using the average flow of electromagnetic energy in the medium. The effects of bandwidth of the pulse and dissipation in the medium have been investigated. While both large bandwidth and large dissipation have similar effects in smoothening out the resonant features that appear due to Fabry-P\'{e}rot resonances, large dissipation can result in very small or even negative traversal times near the resonant frequencies. We have also investigated the traversal times and Wigner delay times for obliquely incident pulses and evanescent pulses. The coupling to slab plasmon polariton modes in frequency ranges with negative $\epsilon$ or $\mu$ is shown to result in large traversal times at the resonant conditions. We also find that the group velocity mainly contributes to the delay times for pulse propagating across a slab with n=-1. We have checked that the traversal times are positive and subluminal for pulses with sufficiently large bandwidths.
Traversal of pulses through negative ($\varepsilon$, $μ$) materials
Lipsa Nanda,S. Anantha Ramakrishna
Physics , 2008, DOI: 10.1117/12.780801
Abstract: We study the traversal times of electromagnetic pulses across dispersive media with negative dielectric permittivity ($\varepsilon$) and magnetic permeability ($\mu$) parameters. First we investigate the transport of optical pulses through an electrical plasma and a negative refractive index medium (NRM) of infinite and semi-infinite extents where no resonant effects come into play. The total delay time of the pulse constitutes of the group delay time and the reshaping delay time as analyzed by Peatross et al \cite{peatross}. For evanescent waves, even with broadband width, the total delay time is negative for an infinite medium whereas it is positive for the semi-infinite case. Evidence of the Hartman effect is seen for small propagation distance compared to the free space pulse length. The reshaping delay mostly dominates the total delay time in NRM whereas it vanishes when $\varepsilon(\omega)=\mu(\omega)$. Next we present results on the propagation times through a dispersive slab. While both large bandwidth and large dissipation have similar effects in smoothening out the resonant features that appear due to Fabry-P\'{e}rot resonances, large dissipation can result in very small or even negative traversal times near the resonant frequencies. We investigate the traversal and the Wigner delay times for obliquely incident pulses. The coupling of evanescent waves to slab plasmon polariton modes results in large traversal times at the resonant conditions. We also find that the group velocity mainly contributes to the delay time for pulse propagating across a slab with refractive index (n) = -1. The traversal times are positive and subluminal for pulses with sufficiently large bandwidths.
CHANGE MANAGEMENT IN NATIONAL SECURITY INSTITUTIONS
Laurentiu BARCAN
Management & Marketing , 2012,
Abstract: Traditional association with defense military security no longer meets the new security environment indicators of national and international scope of the concept extending far beyond military matters to non-military aspects. The experience of recent years shows that national security can be achieved by military means alone, but now includes non-military elements, such as a strong political base emanating from democracy, the rule of law and human rights in education and implementation market economy. Compared with private organization, the change in the public organization is more complex because the preponderance agents or forces generated by environmental change, particularly its political and legal components, internal forces playing a supporting role. The change thus appears to be a deliberate strategy.
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