Correlation of serum lithium levels and thyroid function tests in subjects of bipolar affective disorder: a prospective hospital-based study

Background: Lithium is used in the prophylaxis of long-term therapy of bipolar affective disorder (BPAD) as a mood-stabilizing agent. Thyroid function abnormality is very commonly seen adverse effect, more common in females than males. This study aimed to correlate lithium levels and thyroid function abnormalities associated with it.Methods: Evaluation of medical records of 150 patients in Father Muller Medical College with BPAD, who were treated for 6 months with lithium, carried out from February, 12 2014 to July, 20 2014. Serum lithium levels done by ion selective electrode method in ilyte analyzer and thyroid function test (TFT) by electrochemiluminescence. Data are analyzed by Karl Pearson correlation coefficient.Results: Correlation of lithium levels and TFT in BPAD patients according to Karl Pearson correlation coefficient was negative with significant p<0.002. Among 150 enrolled candidates, 52 (34.67%) were females and 98 (65.4%) were males, 4% (6) patients (3 males and 3 females) had thyroid stimulating hormone (TSH) value <0.27 with an average lithium value of 1.35 mEq/L, 6% (9) patients (5 males and 4 females) had TSH value >4.2 with an average lithium levels of 0.44 mEq/L and 90% of the patients with an average lithium levels 0.66 mEq/L had no thyroid function abnormalities.Conclusions: As already known, Lithium is a drug of narrow therapeutic index and females are more prone for thyroid function abnormalities. Appropriate monitoring of serum lithium levels will aid in necessary dose adjustment and ensure proper utilization of drug

Study to compare the blood sugar profile of the patients on risperidone and olanzapine with divalproex sodium as the common base

Background: Bipolar Affective Disorder which previously was called as manic depressive disorder represents the sixth leading cause of disability. Several preliminary studies suggest that antipsychotic monotherapy or in combination with mood stabiliser have a better prognosis. This study was conducted to compare the blood sugar profile of the patients who are on risperidone and olanzapine with divalproex sodium as the common base.Methods: It was a prospective, comparative, observational, hospital-based clinical study conducted between November 2013 to March 2015. 41 BPAD patients on Risperidone and 38 BPAD patients on Olanzapine were included. A brief history and examination were carried out and the data was entered in a proforma sheet. The investigations carried out were noted. Patients were followed up for a period of 12 weeks i.e. 2,4,8 and 12th = week and the data analysed using SPSS software. Adverse drug events if any were recorded.Results: Our study included 79 treatment-naive patients among whom 17 (21.5%) were women and 62 (78.5%) were men. The polarity of the disease of the majority of the patients was mania at the time of diagnosis. The mean blood sugar levels in risperidone and olanzapine group at the time of diagnosis were 137mg% and 111mg% respectively and weights 62kg and 63.5kg respectively. There was a gradual increase in blood sugar levels and weight from 4th week. At the end of the 12th week, the mean blood sugar levels were 152mg% and 164mg%, weights 65.5kg and 69.5kg in risperidone and olanzapine group respectively.Conclusions: Olanzapine was found to have higher incidence and rapid increase in blood sugar levels which can easily be treated by switching over to another drug. It has been suggested that at least a baseline survey should be undertaken on the prevalence of diabetes in Indian population among patients exposed to antipsychotic drugs

Finite element studies on supersonic panel flutter under high thermal environment with arbitrary flow direction

Panels of re-entry vehicles are subjected to a wide range of flow conditions during ascent and re-entry phases. The flow can vary from subsonic continuum flow to hypersonic rarefied flow with wide ranging dynamic pressure and associated aerodynamic heating. One of the main design considerations is the assurance of safety against panel flutter under the flow conditions characterized by harsh thermal environment. The objectives of this work are to understand the physical principles behind panel flutter under supersonic flow and to make an estimate of the lowering of the critical dynamic pressure (flutter boundary) of the panels due to thermal distributions.13; Analytical and Finite element formulation have been developed for supersonic flutter analysis of rectangular panels subjected various thermal profiles. The piston theory is used for aerodynamic pressure computations. Panels with simply supported edges (with and13; without in-plane edge constraints) have been studied.13; The results obtained by NASTRAN for flow along panel edges are in good agreement with those obtained using the analytical method and the in-house FEM code. From the13; analysis of the results for various flow directions it has been observed that the flow along the longer sides of the panels is most critical. For simply supported panels with no in-plane edge constraints a thermal gradient can cause a drastic fall in the flutter boundary due to in-plane13; thermal stresses that effectively reduce structural stiffness. In-plane edge constraints to thermal expansion further lower the flutter boundary.The present study will be useful for the purpose of panel design in re-entry launch vehicles and supersonic fighter aircrafts

Analytical investigation of supersonic panel flutter under thermal environment with arbitrary flow direction

Panels and Thermal Protection System of re-entry vehicles are subjected to a wide range of flow condition during ascent and reentry phases. The flow can vary from subsonic continuum flow to hypersonic rarefied flow with wide ranging dynamic pressure and associated aerodynamic heating. One of the main design considerations is the assurance of panel safety against panel flutter under the flow conditions characterized by harsh thermal environment. The objectives of this work are to understand the physical principles behind panel flutter under supersonic flow with arbitrary flow angles and given thermal profiles, to make an estimate of the lowering of the critical dynamic pressure (flutter boundary) of the panels due to high thermal distributions in the restrained panels. Using analytical techniques, a mathematical formulation has been developed which can predict flutter boundaries under parabolic distribution of temperature, in addition to the flat temperature profile, over the panels.13; The piston theory is used for aerodynamic pressure computations. Studies have been carried out for rectangular panels of various aspect ratios subjected to flat and parabolic type thermal profiles and various flow directions (restricted on the plane of the panels). The theoretical results are validated with the finite element software package NASTRAN for no thermal condition and flow along x-direction. It has been observed that the flutter boundaries fall sharply with temperature, indicating that a careful study of the actual panels of the vehicle under the anticipated thermal profiles is necessary for design purpose. Furthermore, it has been observed that for any rectangular panel, flow along the longer side is most critical

Probabilistic Flutter Analysis of a Cantilever Wing

A probabilistic flutter analysis of geometrically coupled cantilever wing is carried out using first-order perturbation approach by considering bending and torsional rigidities as Gaussian random variables. The unsteadiness in the aerodynamic flow is modeled using Theodorsen’s thin airfoil theory. The probabilistic response of the wing is obtained in terms of mean, standard deviation, and coefficient of variation (COV) of real and imaginary parts of the eigenvalues at various free stream velocities. The perturbation results are also compared with Monte Carlo simulations. It is observed that the probabilistic response obtained from the perturbation approach is very accurate up to 7% COV in bending rigidity but in the case of torsional rigidity, it starts losing accuracy after 3%

Stochastic Modeling and Reliability Analysis of Wing Flutter

In this work, a physics-based first-order reliability method (FORM) algorithm is proposed for the flutter reliability analysis of an aircraft wing in the frequency domain. The limit state function, which is an implicit function of random variables, is defined in terms of the damping ratio of the aeroelastic system in a conditional sense on flow velocity. Two aeroelastic cases, namely, an airfoil section model and a cantilever wing model, are considered for carrying out the studies. These aeroelastic models have well separated mean bending and mean torsional modal frequencies. The geometric, structural, and aerodynamic parameters of airfoil and wing systems are modeled as independent Gaussian random variables. The effects of these on the statistics of frequency and damping ratio, and the cumulative distribution functions (CDFs) of flutter velocity are studied. In the case of the wing, the effects of modeling stiffness parameters as Gaussian random fields on the CDFs of flutter velocity are also studied. Here, spectral stochastic finite element method (SFEM) based on Karhunen–Loeve (K–L) expansion is used to discretize the random fields into random variables. From the study of an airfoil system, it is observed that parameters like torsional stiffness, elastic axis location, free stream density, and mass moment of inertia are more sensitive as compared with other parameters. However, in the case of the wing parameters such as torsional stiffness, free stream density, mass moment of inertia, and mass are observed to be more sensitive. The CDFs of flutter velocity obtained using the proposed algorithm are compared with Monte Carlo simulations (MCS) and found to be accurate. A comparative study of aeroelastic reliability for the wing is also carried out by treating stiffness parameters as random variables and random fields. It is observed that the CDFs of flutter velocity in the tail region are conservative when stiffness parameters are treated as random variables

Dynamic aeroelastic subsonic discrete gust response analysis of lifting surfaces in time domain using Newark's method.

The Dynamic gust response analysis of lifting surfaces of aerospace structures requires attention to two main factors, namely, the character of the gust and the aeroelastic effects. In the present work,the Dynamic aeroelastic response of subsonic airplane in discrete gusts is determined using Newmark's direct integration method.The adopted time domain method is a departure from the usual modal analysis and the frequency domain approach.The aerodynamic strip theory is assumed,but compressibility and aspect ratio corrections may be included,if desired.The method has been validated by performing discrete gust response analysis of an airfoil model of the elastic wing flying through sharp-edged gust.The unsteady aerodynamic forces on the wing are calculated from the theory of two-dimensional thin airfoils in non-uniform motion.The theory takes proper account of 'unsteadiness' by using the kussner's and Wagner's unsteady lift functions for calculating the aerodynamic forces.The pitching motion and tail effects are neglected.For validating the present work,the responses obtained from Newmark's method is compared with those reported in literature using Laplace method.It is found that the results are in close agreement with reported in the literature

Flutter Reliability Analysis of an Aircraft Wing: A Comparative Study

In this paper, a comparative flutter reliability study is presented for various types of limit state functions using first-order second moment (FOSM) method and the same is compared with Monte Carlo simulation (MCS). For the reliability study, a straight cantilever wing is considered in low subsonic flow, where aerodynamic modeling is based on Theodorsen’s aerodynamic-based strip theory, and for structure, finite element method (FEM) is used. Various parameters such as dimensionless static unbalance, mass moment of inertia, bending stiffness, and torsional stiffness are considered as independent Gaussian random variables. Results show that the probability density functions (PDFs) of various types of limit state function change with parameters, and also for some parameters, the distributions are not unique. The cumulative distribution function (CDF) of flutter velocity among different forms of limit state function obtained from FOSM method is best represented by flutter margin-based limit state function. Among various parameters considered, the most sensitive parameter is torsional stiffness and the least is bending stiffness

A study on the fatigue crack growth behaviour of GTM718 nickel based super alloy under cold-TURBISTAN spectrum loads

In this study, the fatigue crack growth (FCG) behavior of GTM718 nickel base super alloy subjected to cold-TURBISTAN spectrum load sequence was determined by three different methods i.e., (i) Experimental, (ii) Analytical prediction using cycle-by-cycle method and, (iii) Prediction by finite element analysis (FEA). In the experimental method, a standard compact tension (CT) specimen was prepared and pre-cracked to produce a sharp fatigue crack at the notch root. Then, the specimen was subjected to spectrum load blocks repeatedly and crack growth was measured as a function of applied number of flights. Two such tests were carried out in a servo-hydraulic universal test machine with triangular waveform and at an average frequency of 2 Hz. In the second analytical method, the individual load cycles in cold-TURBISTAN spectrum block were separated through rain flow cycle counting method. For each of this counted cycle, the crack extension was determined using crack growth law which was based on two-parameter crack driving force, ΔK*. An in-house MATLAB code was written and used to determine the FCG behavior by cycle-by-cycle method. In the third FEA method, a global model of CT specimen of GTM718 was created in HYPERMESH and a local model with a pre-crack was created in FRANC3D. The FCG behavior under spectrum load was determined using FRANC3D in conjunction with MSC NASTRAN. Two different types of ‘FCG law - stress ratio effect’ combinations were employed i e., Paris’-Walker (P-W) and Bi-linear-Walker (B-W). The required constants for these laws were derived from the available experimental data of the material. It was observed that the predicted FCG behavior by analytical and FEA methods, although conservative, were fairly good when compared to experimental results