Defence Science

Modern encryption algorithms such as AES and DES are designed to produce ciphertext outputs that appear statistically indistinguishable from noise. Assembled into random characters, encrypted text functions to mask patterns and resist statistical analysis. This study aims to investigate whether statistical features extracted from ciphertext chunks can be used to retrace which encryption algorithm was used, and specifically how the inclusion or exclusion of certain statistical features affects classification accuracy. We encrypted four literary texts using three cipher configurations, including AES-CBC, AES-ECB, and DES-ECB. Using these, ten features from 128-byte ciphertext chunks were extracted. We trained a Random Forest classifier on these features and used an analysis in which each feature was systematically removed to measure its contribution to overall accuracy. Our results indicate that three-way classification (AES-CBC vs. AES-ECB vs. DES-ECB) achieves 61.9% accuracy compared to a 33.3% baseline, while two-way classification (AES vs. DES) achieves a 92.8% accuracy. The large accuracy gap between the two tests suggests that choosing between two encryption algorithms leaves stronger statistical differences in ciphertext than choosing between two modes of the same algorithm (CBC vs. ECB). Mean byte value and maximum byte frequency are the most important features, while some top byte frequency features appear to contribute noise, though inconsistently. McNemar's test did not confirm statistical significance for any individual feature removal (all p > 0.05), perhaps due to the limited test set size (n = 48). Our results demonstrate that encryption algorithms leave detectable statistical fingerprints, and that feature selection can allow us to exploit those differences.

Segmented ring transducers are widely used for low frequency, broadband, deep submergence applications. These transducers can be made out of piezoceramic wedges or slabs and metallic wedges. Higher diameter, low frequency transducers are generally made out of piezoceramic slabs and metal wedges due to ease of manufacture and low cost. In this paper, metal ceramic segmented ring transducers are modelled using ATILA, a finite element software for the design of underwater transducers. Transducer variants were modelled with different wedge and piezoceramic materials. Transducers modelled were manufactured, assembled and tested. Various stages of manufacture like piezoceramic stacking, transducer assembly, pre-stressing with fibre winding, and encapsulation are explained. Acoustic performances of the transducers manufactured were measured in an open tank and inside a pressurised vessel from 10 bar to 70 bar. Performance parameters like resonance frequency, transmitting voltage response and directivity were measured. Results indicate that the transducer has usable bandwidth of about two octaves and stable response. One of the transducers was also tested in a high pressure test facility at 600 bar to check its pressure withstanding capability.

Physical oceanographic and acoustic data were simultaneously collected from the coastal waters of the Arabian Sea. Acoustic transmissions were carried out from an anchored vessel using 620 Hz transducer and received by an array of hydrophones moored at ~5 km away from the anchorage. Thermal structure in this region was characterised by a tri-layer structure, ie, a strong thermocline (> 0.4 o C/m) sandwiched between an upper (< 10 m) and bottom (> 25 m) homogeneous layer. High-resolution (sampled at 10 s interval) temperature data from moored sensors revealed intense internal wave activity. The maximum value of Brunt-Vaisala frequency, which is the maximum frequency limit of internal waves in the thermocline, suggests that the upper frequency limit of the internal wave, which can be generated during this period, is 23 cph (2.6 min). High and low frequency waves caused variations of ~3 o C and ~5 o C respectively in the temperature field. But the low frequency internal waves were found to contain maximum energy compared to the high frequency waves. Fluctuations of 8-12 dB were noticed in the measured acoustic intensity values in the presence of low frequency internal waves. Simulation studies carried out using parabolic equation model using 620 Hz source indicated well-defined ducted propagation with minimum transmission loss, when the source was kept within the homogeneous layer. The presence of tri-layer thermal structure, ie, a strong gradient layer sandwiched between an upper and bottom homogeneous layer, caused surface and bottom channel propagation in this region.

The effect of spacers and the enzyme-linked immunosorbent assay (ELISA) formats on the functional parameters of assays such as lower detection limit, inhibitory concentration at 50 per cent (IC50), and specificity were studied. Enzyme conjugates having hydrophobic and hydrophilic spacers were prepared using O-isopropyl methylphosphonic acid (IMPA) and horseradish peroxidase (HRP) as an enzyme label. Comparison was made with reference to enzyme conjugate without any spacer. The present investigation revealed that the presence of a hydrophilic spacer in the enzyme conjugate significantly improves the sensitivity of assays. An enhanced IC50 value achieved was 0.01 μg mL−1 for free antigen detection by direct immunoassay using hydrophilic spacers and precoating of ELISA plates by secondary antibody. The use of a hydrophilic spacer might have helped in projecting the hapten in the aqueous phase, leading to enhanced antibody binding signal and improved sensitivity of the assay.

This paper presents the analysis of wideband polarization insensitive metamaterial absorber with perfect dual resonances. The structure is designed using lossy FR4 substrate with copper layers. The resonating elements are designed using the combination of circular ring with modified circular structure. The resonating elements are printed on the top surface of FR4 substrate, while at the bottom surface is printed with full copper ground plane. Parametric study is done to obtain the optimum design using CST software. From the simulation, the proposed design achieves nearly perfect absorbance at dual resonant frequency with improved bandwidth compared to the general circular ring design. Two peaks absorbance of 98.66% and 99.84% are observed at 9.81 GHz and 10.41 GHz respectively with absorbance bandwidth of 10.29% at normal incident wave. The structure is also simulated for different polarization angles and it is observed that the structure can maintain the absorbance characteristic for all polarization angle.

Standoff photoacoustic spectroscopic technique has been studied for the detection of hazardous molecules adsorbed on surfaces and in vapour/aerosols form in open air. Detection and identification of components in explosive mixtures in trace amounts is very challenging by any point or standoff spectroscopic detection technique. Discusses detection and identification of such components using standoff laser photoacoustic spectroscopic technique. Laser photoacoustic spectra of various trace molecules in the mid-infrared spectral band 7 μm - 9 μm have been recorded in vapor, aerosol, liquid forms as well as samples adsorbed on surfaces such as plastic and cloth. Pulsed quantum cascade laser is modulated at a frequency of 42 kHz resonant with that of microphone. Hazardous chemicals/explosives adsorbed on plastic and cloths surfaces were detected from a standoff distance up to 1.5 m. The sensitivities were found to be 20 μg/cm2, 20 μl liquid and 1.0 ppm corresponding to solid, liquid and v...

Infrared search and track (IRST) systems are required for fighter aircraft to enable them to passively search, detect, track, classify, and prioritise multiple airborne targets under all aspects, look-up, look-down, and co-altitude conditions and engage them at as long ranges as possible. While the IRST systems have been proven in performance for ground-based and naval-based platforms, it is still facing some technical problems for airborne applications. These problems arise from uncertainty in target signature, atmospheric effects, background clutter (especially dense and varying clouds), signal and data processing algorithms to detect potential targets at long ranges and some hardware limitations such as large memory requirement to store and process wide field of view data. In this paper, an overview of airborne IRST as a system has been presented with detailed comparative simulation results of different detectionitracking algorithms and the present status of airborne IRSTs.

The detection and processing of the small moving targets is an important subject in the area of signal/image processing, especially in the condition of complicated background and long ranges . The difficulties for detection of small/point targets arise out of the facts that the target occupies single or few pixels on the image plane of the sensor, has no texture and shape information and has low signal-to-noise plus clutter ratio (SCNR). Target and background are both complex and dynamic. Pre-processing algorithms are used to enhance the SCNR to improve detection probability. The pre-processed image is passed to the detection algorithm to further distinguish between target and background/noise more accurately. Many pre-processing algorithms have been reported in the literature . Some of them are spatial and others are either temporal or spatiotemporal in nature. Median filter 14 is a popular filter for smoothing, enhancement and background prediction of image signals. It has been used very often to reduce "salt and pepper" noise in images. Median filtering is more effective than convolution when the goal is to simultaneously reduce noise and preserve edges. The generalisation of median filter is also called order-statistic (OS) filter. Morphology based filters 7 have been used as pre-processing filters. Other morphological filters like opening and closing filters have high importance in target detection application. Filters primarily used in 1-D signal processing like Gaussian 15 , Weiner 16 , etc. have been tried to judge their performance. The performance of mean 17 , median 14 , max-median 18 , max-

Ascorbic acid, sugars, dehydration ratio and moisture were determined in the vegetables dehydrated separately in solar drier and in electrical oven under similar conditions by standard methods. Vegetables examined were cabbage, cauliflower, tomato, radish, turnip, lahi, methi and palak. It was revealed that in each case, contents of ascorbic acid were higher in solar-dried vegetables in comparison to oven-dried stuffs. This finding indicated superiority of solar driers over electrical ovens, both in reference to quality of the dehydrated vegetables and its overall cost of operation

This study employs the Laplace-Adomian Polynomial Method (LAPM) to obtain approximate solutions for both linear and nonlinear ordinary differential equations. LAPM integrates the Laplace transform with Adomian polynomials to manage nonlinear terms effectively, avoiding the need for linearization or perturbation techniques. To evaluate the method's accuracy and computational efficiency, three representative examples were solved, with the results benchmarked against corresponding exact solutions. The numerical outcomes, presented through tables and graphical comparisons, demonstrate that LAPM provides highly accurate approximations with minimal error using only a few series terms. The findings affirm that the method is not only straightforward and computationally efficient but also broadly applicable to various nonlinear problems. Given its robustness and simplicity, LAPM holds promise for extension to more complex systems, including partial differential equations and multi-dimensional models in applied sciences.

This study evaluates the geometric optimization of convergent-Divergent (C-D) rocket nozzles by examining the complex relationship between nozzle contours and thermodynamic irreversibilites. Departing from conventional thrust-centric designs, this research prioritizes the reduction of entropy generation as a critical factor in enhancing propulsion performance, utilizing a customized Python-driven computational framework, the flow characteristics of various Bell and conical nozzle geometries were analyzed under supersonic conditions. The methodology incorporates second-law analysis to quantify energy losses induced by boundary layer effects and shock Interactions. This work offers a refined analytical approach for developing high-efficiency propulsion systems fore, modern space exploration,

This study employs the Laplace-Adomian Polynomial Method (LAPM) to obtain approximate solutions for both linear and nonlinear ordinary differential equations. LAPM integrates the Laplace transform with Adomian polynomials to manage nonlinear terms effectively, avoiding the need for linearization or perturbation techniques. To evaluate the method's accuracy and computational efficiency, three representative examples were solved, with the results benchmarked against corresponding exact solutions. The numerical outcomes, presented through tables and graphical comparisons, demonstrate that LAPM provides highly accurate approximations with minimal error using only a few series terms. The findings affirm that the method is not only straightforward and computationally efficient but also broadly applicable to various nonlinear problems. Given its robustness and simplicity, LAPM holds promise for extension to more complex systems, including partial differential equations and multi-dimensional models in applied sciences.

A 2,4,6-trinitrotoluene (TNT) utilising bacterium, Pseudomonas species (strain KA) was isolated from soils of a munitions processing unit and studied for its ability to grow and metaholise TNT. The result indicated that the isolate could grow aerobically in a minimal salt medium containing 0.25 mM1l TNT at 3 0 % It could completely transform 0.25 mMll TNT in 5 days giving 2-isomeric monoaminodinitrotoluenes, namely 4-aminodinitrotoluene and 2-aminodinitrotoluene. Products of TNT transformation were analysed and confirmed by thin layer chromatography and gas chromatography coupled with mass spectrometry. Both, growth of the isolate and biotransformation rates were better supported on sugar and ammonium salt when added to themedium separately. Pseudomonas species (strain KA) showed maximum TNT transformation efficiency in the presence of mannose. For degradation of TNT, this strain can be employed to initiate the process in association with the other microbial members that can collectively degrade TNT.

In this report we show how to adapt the notion of "attack surface" to formally evaluate security properties at the architectural level of design and to identify vulnerabilities in architectural designs. Further we explore the application of this metric in the context of architecture-based transformations to improve security by reducing the attack surface. These transformations are described in detail and validated with a simple experiment.

This work is published open source in the name of science, so all scientists can test and evaluate the formulation. Polymers for full scale industrial production will not be given here, but the given ones will be good enough for small scale production and testing. H-TBX is a cast-cured polymer bonded explosive. That is mixed, loaded into ordnance and then cured to a solid mass with Shore A = 40 hardness. Polymer bonded explosive H-TBX contains the next components in the next MASS proportions: 16% Silicone polymer (Ecoflex 0030-both components) 16% Potassium perchlorate 28% Aluminum powder 8 micron 40% White crystalline hexogen powder That is for 100 grams mixture-16 grams silicone polymer, 16 grams potassium perchlorate; 28 grams aluminum powder and 40 grams hexogen powder. When preparing the mixture keep in mind that the density of the polymer Ecoflex 0030 is 1.07 g/cm 3 and it is two component silicone and 16% are-component 1 + component 2. The potassium perchlorate (KP) Standard for pyrotechnics KP can be used, milled on site to less than 20-30 micron. KP with or without carb-o-sil anticake agent can be used. Commercially available: http://www.highqualitychems.com/potassium-perchlorate-w-cab-o-sil/ Only carb-o-sil or other SiO2 based anticake agent is acceptable, anticake agents based on phosphates and other chemicals must not be used as they can inhibit the catalyst of the polymer! Potassium perchlorate alternatively can be ball milled on site to less than 30 micron and used directly to prepare the H-TBX. In their experience SURT Tech. used mechanical coffee grinders to mill the KP without problems. Potassium perchlorate must be free of chlorates! Polymer: The polymer is the two component liquid platinum cure silicone Ecoflex 0030.

The efficacy of dibenz (b,f)-1 ,4-oxazepine (CR), a potent sensory irritant and deltarnethrin a wellknown insecticide, in providing protection to the multi-element nylon tapes, used as aircraft arresters at airports have been evaluated. The results obtained indicate that 5 per cent CR-admixed UV resistant nylon tapes got adequate protection against attacks from wild type laboratory bred Rattus rattus for up to 160 days. CR treatment was found to be water wash resistant against 7, 30 and 60 days protection offered by 3, 4 and 5 per cent deltarnethrin, respectively.

Prediction of flight characteristics of a store in the vicinity of an aircraft is vitally important for ensuring the safety of the aircraft and effectiveness of the store to meet the mission objective. Separation dynamics of an agile air-to-air-Missile from a fighter aircraft is numerically simulated using an integrated store separation dynamics suite. Chimera cloud of points along with a grid-free Euler solver is used to obtain aerodynamic force on the missile and the force is integrated using a rigid body dynamics code to obtain the missile position. In the present work, the suite is applied to a flight test case and sensitivity of trajectory variables on launch parameters is studied. Further, the results of the suite are compared with the flight data. The predicted body rates and Euler angles of missile compare well with the flight data.  

Investment casting process is used worldwide to manufacture as cast precision castings specially for super alloy castings mainly for Aerospace and Automotive Industry. The process of investment castings is very complicated compared to other commonly used casting processes. Very crucial stages in this process are 1) first coat of zircon silica on pattern assembly and 2) Metal pouring in preheated shells. These two stages of the investment casting processes are usually performed manually in small scale Investment casting foundries causing defects which increase the cost of quality and scrap. This increases delivery lead time affecting profit gains. This scenario is typical for small scale investment casting foundries making small yet high production castings.

The pyrotechnic slowing-down composition on the basis of the modified mixture consisting of polymer and powder of metal, ammonium nitrate, an epoxide resin and chromate of barium is developed. In the development of recipes composition is determined the ratio between the oxidant and fuel, which could provide the stable combustion at low speed. Barium chromate was introduced into composition as the retarder and to reduce the burning rate. The resulting delay composition has a low sensitivity to friction and shock, do not require special storage and special vehicles for transportation, it has a high physical and chemical stability. The gas generator equipped with this delaying composition most suitable for processing bottom-hole zones of oil and uranium wells. It is shown that using methods of mechanochemical modification of components of heterogeneous condensed systems, it is possible to influence actively process of their combustion and to increase their effectiveness and completenes...

Investment casting process is used worldwide to manufacture as cast precision, specially for super alloy castings mainly for Aerospace and Automotive Industry. The process of investment castings is very complicated compared to other commonly used casting processes. Very crucial stage in this process is first coat of zircon silica on pattern assembly. It is a very critical stage as this coat comes in contact directly with poured molten metal with temperature ranging from 1100-2000 0 C. With consideration of an effect of automation using robotics to improve quality of investment castings with consistency for first coat of silica, advantages are discussed for simple and economical ways to reduce defects and improve quality of castings than by expensive and bulky existing available systems. These solutions will be more beneficial to small scale investment casting foundries with different range of products.

low insertion loss, and a compact structure. The objective is to create a filter that supports multiple passbands with minimal interference and high performance. These tools help verify performance and prepare the filter design for potential fabrication. The design of a dual band band-pass filter for wind profiling radar and 5G communication requires careful planning to ensure high performance, low losses and precise frequency selection. The key objectives of this project are: • To design a dual band band-pass filter for L-band (1.3 GHz) and S-band (3.55 GHz) using HFSS software.

CaSO4:Eu phosphor is synthesised by acid distillation method with varying synthesis parameters for studying its Radiophotoluminescence (RPL) properties for gamma absorbed dose measurements. Five phosphor samples are prepared by varying quantity of solvent, distillation temperature and reaction time. XRD, SEM, particle size analysis and photoluminescence studies are carried out. The characterisation study shows polycrystalline luminescent particles of average size varying from 35 μm to 55 μm. Characteristic emission of Eu3+ is observed around 590, 615 and 620 nm at 242 nm excitation. Gamma dose response of maximum Eu3+ PL intensity sample is studied in the range 10 cGy to 1000 cGy using Co-60 source. Gamma radiation exposure induces conversion of Eu3+ to Eu2+ giving luminescence at 385 nm with 320 nm excitation. Repetitive measurements of gamma exposed samples are carried out and no significant fading is observed within one week of post-irradiation. The phosphor has the potential to ...

In this paper we prove that no signed graph on the complete graph K p , p ≥ 6, is graceful, and we also give a characterization of graceful signed graphs on K p , p ≤ 5. This implies that there is no subset A of cardinality p ≥ 6 from the set {0, 1, . . . , p 2 -n}, n ≤ 1 2 p 2 , such that each element of the set {1, 2, . . . , n} occurs exactly twice and each element of the remaining set {n + 1, n + 2, . . . , p 2 -n} occurs exactly once as an absolute value of a pair of distinct elements of A. Also, all such subsets of cardinality p ≤ 5 are determined.

The problem of heat transfer for the steady axi-symmetrical laminar source flow of a slightly rarefied electrically conducting gas between two infinite parallel circular disks under transverse magnetic field is analytically investigated where both Joulean and viscous heating are considered. The flow parameters and the temperature are expanded in powers of llr. The quantity of heat transfer per unit time from a finite dlsk has been calculated. It is found that with the increase of magnetic field, the rate of heat transfer from the lower disk decreases and increases from the upper disk. The maximum temperature increases with the increase of the magnetic field. The rate of heat transfer from both the disks as well as the maximum temperature decreases with the increase of the rarefication of thegas.

CTIA Capacitance trans-impedance amplifier Ea Activation energy IRFPA Infrared focal plane array I²C Inter integrated circuit link NETD Noise equivalent temperature difference NUC Non uniformity correction OTP One time programmable PROM Programmable read only memory PLP Pixel level package ROIC Read out integrated circuit TWS Thermal weapons sight TEC Thermo electric cooler VGA Video graphic array (640 x 480 pixels) WLP Wafer level package XGA Extended graphic array(1024 x 768 pixels) For some years the infrared sensors market tends to follow the evolution observed in the past for visible imaging sensors. It is particularly true for cost decreasing, to address high volumes applications, while more and more performances are expected from the sensors. Indeed with smaller pixel pitch, higher resolution and easier system integration, microbolometer infrared sensors intend to address military application but also new low-cost/high-volume applications such as thermography, security/surveillance and automotive driver vision enhancement. A ¼ VGA sensor has been designed taking into account up to date 17 µm pixel-size technology and high reliability packaging technique. We will first describe the interest of amorphous silicon for microbolometer applications regarding material properties, simplified technological process and simplified sensor operation. The ¼ VGA sensor will be described in terms of ROIC architecture, packaging and performances. Amorphous silicon presents attractive properties for micro bolometer applications. The amorphous silicon bolometer resistance R variation versus temperature is described by Arrhenius law, in Eqn. (1), in which activation energy E a depends on the sensitive material. R=R 0 .exp(E a /kT) (1) As amorphous silicon is not an alloy, every pixel has the same activation energy (standard deviation on mean value < 0.04%) leading to a high spatial uniformity of pixels temperature behaviour. Moreover, amorphous silicon activation

A computer code has been developed for internal ballistic performance evaluation of solid rocket motors, using minimum distance function (MDF) approach for prediction of geometry evolution. This method can handle any complex geometry without the need to define different geometrical shapes and their evolution as used in several existing analytical geometry evolution-based methodologies. The code is validated with both experimental results published in literature, as well as for solid rocket motors of tactical and strategic missiles and a very good match is obtained with static test results. The output of the code gives pressure-time (p-t) curve as well as the detailed parameters of the flow along the axial direction, and geometries in the form of mesh file, which can be further used as input to codes for CFD analysis.

Composite materials are increasingly being considered and used for launch-vehicle structures. For shell structures, such as interstages, skirts, and shrouds, honeycomb-core sandwich composites are often selected for their structural efficiency. Therefore, it is becoming increasingly important to understand the structural response, including buckling, of sandwich composite shell structures. Additionally, small geometric imperfections can significantly influence the buckling response, including considerably reducing the buckling load, of shell structures. Thus, both the response of the theoretically perfect structure and the buckling imperfection sensitivity must be considered during the design of such structures. To address the latter, empirically derived design factors, called buckling knockdown factors (KDFs), were developed by NASA in the 1960s to account for this buckling imperfection sensitivity during design. However, most of the test-article designs used in the development of these recommendations are not relevant to modern launch-vehicle constructions and material systems, and in particular, no composite test articles were considered. Herein, a twopart study on composite sandwich shells to (1) examine the relationship between the buckling knockdown factor and the areal mass of optimized designs, and (2) to interrogate the imperfection sensitivity of those optimized designs is presented. Four structures from recent NASA launch-vehicle development activities are considered. First, designs optimized for both strength and stability were generated for each of these structures using design optimization software and a range of buckling knockdown factors; it was found that the designed areal masses varied by between 6.1% and 19.6% over knockdown factors ranging from 0.6 to 0.9. Next, the buckling imperfection sensitivity of the optimized designs is explored using nonlinear finite-element analysis and the as-measured shape of a large-scale composite cylindrical shell. When compared with the current buckling design recommendations, the results suggest that the current recommendations are overly conservative and that the development of new recommendations could reduce the acreage areal mass of many composite sandwich shell designs by between 4% and 19%, depending on the structure.

We report on production compatible low temperature (⩽320 °C) selective epitaxial growth schemes for boron doped Ge 0.99 Sn 0.01 and Ge in source/ drain areas of FinFET and gate-all-around (GAA) strained-Ge pMOS transistors. Active B concentrations are as high as 3.2 × 10 20 cm -3 and 2.2 × 10 20 cm -3 for Ge 0.99 Sn 0.01 and Ge, respectively. The Ge:B growth is based on a cyclic deposition and etch approach using Cl 2 as an etchant, while the Ge 0.99 Sn 0.01 :B growth is selective in nature. Low Ti/p+ Ge(Sn):B contact resistivities of 3.6 × 10 -9 Ω cm 2 (Ge 0.99 Sn 0.01 ) and 5.5 × 10 -9 Ω cm 2 (Ge:B) have been obtained without any post-epi activation anneal. This work is the first demonstration of a selective, conformally doped Ge 1-x Sn x :B source/drain epi implemented on Ge FinFET device structure with fin widths down to 10 nm and on GAA devices (horizontal compressively strained-Ge nanowires).

The biochemical changes taking place in human subjects following de-induction to plains from high altitude (5700-6100 m) after a prolonged slay of 9-13 months were investigated in 120 soldieri in four groups of 30 each on day 5, 30, 60 and 90 after their descent. One group of soldiers, who were never posted at high altitude served as control. Haemoglobin levels, which were initiallv hieh after 5 dnvs of de-induction droooed lo sienificantlv lower levels in the erouo , u . L ., " . studied on day 60 after de-induction. No clinically abnormal changes were noted in activities of serum enzymes, ie, aspartate aminotransferase, alanine aminotransferase and y-glutamyl transpeptidase. Alanine aminotransferase activity was found significantly elevated in 5-day group (53.1 i 0 . 2 4 IUII). Cholesterol and triglyceride levels were higher in 30-day group in comparison to groups studied on day 5,60 and 90 after de-induction from high altitude. Activity of glutathione S-transferase was more in groups studied on day 30 and 60 and may he in response to increased demand for detoxification of certain metabolites. Endogenous creatinine clearance was impaired with concomitant increase in serum creatinine levels. The creatinine clearance returned to normal only in group studied on day 90 after de-induction. Testosterone and estradiol levels were within normal physiological limits. However, there was increase in testosterone levels following ds-~nduction. Results of this cross-sectional study indicate that it takes 1-3 months after de-induction from high altitude for biochemical parameters to reach normal levels.