923 resultados para endoscopic third ventriculostomy


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Letter (copy) in three sections (1 ½ pages, handwritten). The first part is addressed to Henry Nelles from M. Douglass in which Mr. Douglass says he has enclosed $50. This section is dated Feb. 8, 1830. The second part is also addressed to Henry Nelles and is signed Mr. D. This is the section that says “your letter has just come stating that you had received a letter but the $50 was not in the letter. There was $50 in it when it left this post office. This is dated Feb. 14, 1830. The third part is addressed to Mr. Griffen from George M. Richardson. It says that this is to certify that Mr. Douglass did mail $50 on the 18th of this month. This letter is stained and slightly torn. Some of the text is affected. [This letter has to do with the case about the missing money which is included in this collection], Feb. 8, 1830.

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UANL

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The fashionable widespreading of Sen’s ideas coincides with a new mood in the shaping of public policies in affluent societies. In Europe indeed, an “opportunity”-based approach to social security has been implemented through the European Employment Strategy. Public action tends to rely on a procedural concern with individual opportunities or potentialities in the labour market. The underlying ethics is that individuals are then responsible to use these background opportunities in order to lead the kind of life they value most. More broadly, the discourse and practice of the so-called “Third Way” shares with the capability approach an appeal for a procedural and enabling depiction of the role of the State. The paper intends to clarify the relation between procedural and opportunity-based approaches to social justice, among them the capability approach, and these new patterns of public action. Our vision goes in the way of a yet renewed, but deeper action of the welfare state, where social agency is envisaged as the very condition of individual agency. Drawing on the various critics of mainstream equality of opportunity, two opposed approaches to responsibility are identified: on the one hand, responsibility is conceived of as i) a “luck vs. choice” fixed starting point, ii) a backward-looking conception and iii) a highly individualistic framework. On the other hand, responsibility is envisaged as i) an outcome of public policies rather than a starting point, ii) a forward-looking conception, and iii) a combined institutional-individual framework. We situate here Sen’s capability approach, as well as critics of the luck egalitarianism path. The Third Way rhetoric is assessed against both these perspectives. The issue eventually boils down to an ethical reflection on the articulation of responsibilities, and to a pragmatic and substantial concern for the content of what providing security should mean in practice.

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Third order nonlinear susceptibility χ(3) and second hyperpolarizability (γ) of a bis-naphthalocyanine viz. europium naphthalocyanines, Eu(Nc)2, were measured in dimethyl formamide solution using degenerate four wave mixing at 532 nm under nanosecond pulse excitation. Effective nonlinear absorption coefficient, βeff and imaginary part of nonlinear susceptibility, Im(χ(3)) were obtained using open aperture /Z-scan technique at the same wavelength. Optical limiting property of the sample was also investigated. The role of excited state absorption in deciding the nonlinear properties of this material is discussed.

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Wavelength dependence of saturable absorption (SA) and reverse saturable absorption (RSA) of zinc phthalocyanine was studied using 10 Hz, 8 ns pulses from a tunable laser, in the wavelength range of 520–686 nm, which includes the rising edge of the Q band in the electronic absorption spectrum. The nonlinear response is wavelength dependent and switching from RSA to SA has been observed as the excitation wavelength changes from the low absorption window region to higher absorption regime near the Q band. The SA again changes back to RSA when we further move over to the infrared region. Values of the imaginary part of third order susceptibility are calculated for various wavelengths in this range. This study is important in identifying the spectral range over which the nonlinear material acts as RSA based optical limiter.

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Wavelength dependence of saturable absorption (SA) and reverse saturable absorption (RSA) of zinc phthalocyanine was studied using 10 Hz, 8 ns pulses from a tunable laser, in the wavelength range of 520–686 nm, which includes the rising edge of the Q band in the electronic absorption spectrum. The nonlinear response is wavelength dependent and switching from RSA to SA has been observed as the excitation wavelength changes from the low absorption window region to higher absorption regime near the Q band. The SA again changes back to RSA when we further move over to the infrared region. Values of the imaginary part of third order susceptibility are calculated for various wavelengths in this range. This study is important in identifying the spectral range over which the nonlinear material acts as RSA based optical limiter.

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We have measured the changes in the ultrasonic wave velocity, induced by the application of uniaxial stresses in a Cu-Al-Ni single crystal. From these measurements, the complete set of third-order elastic constants has been obtained. The comparison of results for Cu-Al-Ni with available data for other Cu-based alloys has shown that all these alloys exhibit similar anharmonic behavior. By using the measured elastic constants in a Landau expansion for elastic phase transitions, we have been able to give an estimation of the value of a fourth-order elastic constants combination. The experiments have also shown that the application of a stress in the [001] direction, reduces the material resistance to a (110)[110] shear and thus favors the martensitic transition.

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In a recent paper A. S. Johal and D. J. Dunstan [Phys. Rev. B 73, 024106 (2006)] have applied multivariate linear regression analysis to the published data of the change in ultrasonic velocity with applied stress. The aim is to obtain the best estimates for the third-order elastic constants in cubic materials. From such an analysis they conclude that uniaxial stress data on metals turns out to be nearly useless by itself. The purpose of this comment is to point out that by a proper analysis of uniaxial stress data it is possible to obtain reliable values of third-order elastic constants in cubic metals and alloys. Cu-based shape memory alloys are used as an illustrative example.

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Salient pole brushless alternators coupled to IC engines are extensively used as stand-by power supply units for meeting in- dustrial power demands. Design of such generators demands high power to weight ratio, high e ciency and low cost per KVA out- put. Moreover, the performance characteristics of such machines like voltage regulation and short circuit ratio (SCR) are critical when these machines are put into parallel operation and alterna- tors for critical applications like defence and aerospace demand very low harmonic content in the output voltage. While designing such alternators, accurate prediction of machine characteristics, including total harmonic distortion (THD) is essential to mini- mize development cost and time. Total harmonic distortion in the output voltage of alternators should be as low as possible especially when powering very sophis- ticated and critical applications. The output voltage waveform of a practical AC generator is replica of the space distribution of the ux density in the air gap and several factors such as shape of the rotor pole face, core saturation, slotting and style of coil disposition make the realization of a sinusoidal air gap ux wave impossible. These ux harmonics introduce undesirable e ects on the alternator performance like high neutral current due to triplen harmonics, voltage distortion, noise, vibration, excessive heating and also extra losses resulting in poor e ciency, which in turn necessitate de-rating of the machine especially when connected to non-linear loads. As an important control unit of brushless alternator, the excitation system and its dynamic performance has a direct impact on alternator's stability and reliability. The thesis explores design and implementation of an excitation i system utilizing third harmonic ux in the air gap of brushless al- ternators, using an additional auxiliary winding, wound for 1=3rd pole pitch, embedded into the stator slots and electrically iso- lated from the main winding. In the third harmonic excitation system, the combined e ect of two auxiliary windings, one with 2=3rd pitch and another third harmonic winding with 1=3rd pitch, are used to ensure good voltage regulation without an electronic automatic voltage regulator (AVR) and also reduces the total harmonic content in the output voltage, cost e ectively. The design of the third harmonic winding by analytic methods demands accurate calculation of third harmonic ux density in the air gap of the machine. However, precise estimation of the amplitude of third harmonic ux in the air gap of a machine by conventional design procedures is di cult due to complex geome- try of the machine and non-linear characteristics of the magnetic materials. As such, prediction of the eld parameters by conven- tional design methods is unreliable and hence virtual prototyping of the machine is done to enable accurate design of the third har- monic excitation system. In the design and development cycle of electrical machines, it is recognized that the use of analytical and experimental methods followed by expensive and in exible prototyping is time consum- ing and no longer cost e ective. Due to advancements in com- putational capabilities over recent years, nite element method (FEM) based virtual prototyping has become an attractive al- ternative to well established semi-analytical and empirical design methods as well as to the still popular trial and error approach followed by the costly and time consuming prototyping. Hence, by virtually prototyping the alternator using FEM, the important performance characteristics of the machine are predicted. Design of third harmonic excitation system is done with the help of results obtained from virtual prototype of the machine. Third harmonic excitation (THE) system is implemented in a 45 KVA ii experimental machine and experiments are conducted to validate the simulation results. Simulation and experimental results show that by utilizing third harmonic ux in the air gap of the ma- chine for excitation purposes during loaded conditions, triplen harmonic content in the output phase voltage is signi cantly re- duced. The prototype machine with third harmonic excitation system designed and developed based on FEM analysis proved to be economical due to its simplicity and has the added advan- tage of reduced harmonics in the output phase voltage.

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La pancreatitis aguda (PA) es una patología clínica común que abarca un espectro desde leve hasta fatal, donde se produce una inflamación del páncreas por auto digestión enzimática con grado variable de compromiso sistémico. Es una emergencia abdominal grave con una mortalidad del 9-23%. En el 40% de los casos de pancreatitis aguda se encuentra que es de origen biliar. La prevalencia de enfermedad biliar a nivel mundial en adultos varía entre 5,9% y 21,9%, con grandes variaciones geográficas y regionales, se encuentran en el 12% de los hombres y el 24% de las mujeres. La prevalencia aumenta con la edad. Latinoamérica es una región con alta prevalencia. En pacientes con colelitiasis del 5-15 % tienen coledocolitiasis. La alta prevalencia de la patología biliar en nuestro país hace que esta sea una causa frecuente de consulta médica por dolor abdominal. El factor común presente en la gran mayoría de las enfermedades de la vía biliar es la Colelitiasis. La complicación más frecuente, la Coledocolitiasis, se ha reportado con cifras hasta de un 20% y como complicación de esta la pancreatitis. La pancreatitis aguda de origen biliar (PAB) es causada por una obstrucción transitoria o persistente de la ampolla de Váter por barro biliar o por cálculos. En el diagnostico de la PAB se emplean métodos invasivos como la colangiopancreaticografia endoscópica retrograda (CPRE) la cual trae consigo morbilidad y mortalidad asociada y métodos no invasivos como la colangiopancreaticografia magnética (CRM) que emerge como modalidad prometedora en el diagnostico y manejo de la PAB en centros de tercer y cuarto nivel de complejidad. El manejo actual de la PAB es la remoción de la obstrucción del conducto biliar común (CBC) seguida de su tratamiento definitivo, la colecistectomía o CPRE con papilotomia. En nuestro país no se han publicado estudios con datos locales acerca de la utilidad de la CRM para la detección de coledocolitiasis, en las guías de manejo de coledocolitiasis de la asociación colombiana de cirugía publicadas en el año 2004, hace referencia de la utilidad de la CRM para el diagnostico de esta entidad tomando como base una revisión sistemática de estudios publicados en Medline, Pubmed y Cocrane los cuales no incluyen experiencia a nivel nacional. En este estudio pretendimos determinar cuáles son los pacientes que se benefician de la realización de CRM temprana en el marco de la PAB leve para la detección de coledocolitiasis.