Volume

Volume 43 - Year :1993

(44)

Issue 3-July 1993

(14)

	Theories for Skilled Limb Movements Author : Agarwal, Gyan C. Source : Defence Science Journal ; Vol:43(3) ; 1993 ; pp 187-200 Subject : 57.089 Biomedical Sciences Keywords : Alpha gamma control;Perform skilled limb movements;Amplitude modulation Abstract : Some of the theories that have been advanced to perform skilled limb movements are reviewed in this paper. The aspects discussed in brief include alpha-gamma control, choice of control variables in limb movements, equilibrium point hypotheses, experimental observations from simple movement studies and explanations proposed, in particular the dual strategy hypothesis. The single mechanical degree-of-freedom movements may be controlled by one of two strategies: a speed-insensitive strategy or a speed-sensitive strategy. The term strategy implies a set of rules which specify in terms of task variables and subject instructions how to choose the excitation signal, the controlling signal at the alpha motoneuron level. The two strategies differ in that speed-insensitive strategy is a result of duration modulation of the excitation pulse, whereas the speed-sensitive strategy is a result from amplitude modulation. Finally, the problem of multi-degrees of freedom movements and the role of higher motor control centres are discussed in brief.
	The Effect of External Loads and Cyclic Loading on Normal Patellofemoral Joint Signals Author : Ladly, K.O.;Frank, C.B.;Bell, G.D.;Zhang, Y.T.;Rangayyan, R.M. Source : Defence Science Journal ; Vol:43(3) ; 1993 ; pp 201-210 Subject : 57.089 Biomedical Sciences ;61 Medical Sciences Keywords : Vibroarthrography;Chondromalacia patella Abstract : Pain over the anterior portion of the knee joint is a common clinical complaint. A condition known as 'chondromalacia patella' (softening of the cartilage under the patella), which frequently causes anterior knee pain is difficult to diagnose and monitor. Vibrations detected by a contact transducer over the patellofemoral joint may be useful in the assessment of chondromalacia patella. This paper utilised this technique known as vibroarthrography (VAG), to study two potential sources of variability of the normal patellofemoral joint signal. The effect of increased muscular force on the VAG signal was measured by externally loading the joint. The effect of load history (cyclic loading) on the VAG signal was determined by comparing signals before, during, and after application of weights under similar cyclic loading conditions. Results indicated that external loading of the patellofemoral joint caused only minor signal variation. Cyclical loading of the joint, on the other hand, was determined to be a major source of variability of the normal patellofemoral joint signal, which must be controlled in future VAG tests.
	Real Time Visual Displays in Speech and Singing Author : Howard, David M. Source : Defence Science Journal ; Vol:43(3) ; 1993 ; pp 211-221 Subject : 621.38 Electronics Keywords : Signal processing devices;Real time displays;Transputers;Real time visual displays Abstract : Many branches of the speech, hearing and singing research community use analyses of aspects of the voice source and overall spectral changes. By these means, patterned variations have been noted in both the voice source and the acoustic output from the vocal tract during speech and singing, the speech/singing of professional voice users and pathological speech. The widespread availability of fast computers and dedicated signal processing devices has enabled many of these techniques to be made available as real-time displays to a wide range of users. This paper describes a number of real-time visual displays of voice source, the acoustic output and articulatory gestures during speech and singing. The development of analysis techniques based on a model derived from the results of contemporary psychoacoustic experiments into the nature of the human peripheral hearing mechanism is discussed. This model depends on parallelism which is ideally suited to implementation on transpires which are specifically designed to operate in parallel. Developments such as these may further our understanding of the relative importance of voice source and acoustic cues in speech and singing, whether normal, professional or pathological, and enable a new generation of real-time visual displays to be implemented.
	Zero Crossing Edge Detection and Contour Tracing for Segmentation of Cervical Cell Nucleus Author : Ramesh, B.V.;Raghunandan, S.;Ramakrishnan, K.R. Source : Defence Science Journal ; Vol:43(3) ; 1993 ; pp 223-228 Subject : 57.089 Biomedical Sciences ;61 Medical Sciences Keywords : Algorithm;Gaussian operator Abstract : To automate the process of screening of normal and abnormal cervical cells, there is a need for automatic segmentation of the nucleus of these cells. This paper presents an algorithm using the Laplacian of Gaussian operator and contour tracer to segment the nucleus from the background. The algorithm has been tested on different kinds of images of cervical cells.
	Morphometric Studies of Cytological Specimens in Breast Carcinoma using Computerised Image Analysis System Author : Padaki, V.C.;Hegde, K.S.;Ramesh, B.V.;Sumathi, S.R.;Hazarika, D.;Kumar, Prashantha;Verghese, C.A. Source : Defence Science Journal ; Vol:43(3) ; 1993 ; pp 229-233 Subject : 61 Medical Sciences Keywords : Image analysis;Radical mastectomy;Computerised interactive morphometry Abstract : The value of nuclear parameters were determined using interactive computer image analysis system on 100 preoperative FNAC smears of breast lesion were radical mastectomy was performed subsequently. Twenty cases of benign lesion were taken as control. The lymph node status was correlated with the nuclear and nucleolar variables. It is found that few nuclear parameters have good discriminatory power. Computerised interactive morphometry proved to be far superior to eye-piece measurements with respect to accuracy, reproducibility and time taken for parameter estimation which leads to the determination of better prognostic indicator.
	Ultrasonic Hyperthermia for Cancer Treatment Author : Singh, V.R.;Shriwastava, Mahesh Source : Defence Science Journal ; Vol:43(3) ; 1993 ; pp 235-241 Subject : 57.089 Biomedical Sciences ;61 Medical Sciences Keywords : Ultrasonic focusing techniques;Hyperthermia;Ultrasonic hyperthermia Abstract : In this paper, design of transducers, ultrasonic focusing techniques and temperature monitoring for hyperthermia are described. Efforts being made at National Physical Laboratory, New Delhi, on the development of an indigeneous ultrasonic hyperthermia and non-invasive temperature monitoring systems are discussed.
	ANAMICA: A Medical Data Visualisation and Characterisation Author : Sundar, R.;Venkataramanan, N.;Srinivasan, N. ;Ramesh, N.;Athithan, G. Source : Defence Science Journal ; Vol:43(3) ; 1993 ; pp 243-252 Subject : 57.089 Biomedical Sciences Keywords : Computer tomography;Magnetic risonance imaging;Image processing;Histograms Abstract : This paper reports the design and implementation of ANAMICA, a three-dimensional (3-D) medical data visualisation and characterisation system which provides a complete set of image processing options. Constructions of internal surfaces from total or partial volume of 3-D data and cut-out views are supported by means of 'volume rendering' as well as object space methods. Arbitrary planar and curved sections of 3-D data can be obtained and processed subsequently as standard 2-D images. Volumetrics and a preliminary characterisation of tissues based on histograms are also supported. A window based user-interface provides convenient access to all these options.
	Biomedical Applications of Simulated Environments Author : Selvamurthy, W. Source : Defence Science Journal ; Vol:43(3) ; 1993 ; pp 253-258 Subject : 57.089 Biomedical Sciences Keywords : Environmental physiology;Human decomposition chamber;Portable oxygen regenerator Abstract : Environmental physiology assumes great significance in our national context of the diverse climatic conditions prevailing in different regions. Troops have to operate in diverse environmental conditions guarding the frontiers. Hence, the research in this area has been focused on the usage of field studies in the natural environments or simulated environments in the laboratory. Besides, the application of the simulation chambers in the research on the physiological effects of diverse environments, these studies may have applications in the control and management of certain clinical disorders. Some simulation chambers and specilised set-ups have been designed and developed at the Defence Institute of Physiology and Allied Sciences to carry out simulation studies. This paper describes these developments and the potentials of these biomedical applications of simulated environments.
	Developments of RF Coil for P in vivo NMR Spectroscopy Author : Khushu, S.;Mehta, S.B.;Chandra, Sushil ;Jena, A. Source : Defence Science Journal ; Vol:43(3) ; 1993 ; pp 259-262 Subject : 681.2 Instrumentation Keywords : Thyroid spectroscopy;Superconductivity NMR System Abstract : RF receiver coils are very important parts of an NMR System. The design of these coils is very critical and has a dramatic effect on the SNR of the NMR signal and are generally developed in TRA/REC mode. This paper reports the developments of a 3.5 cm TRA/REC 26 MHz RF coil for P spectroscopy of small organs like thyroid. The coil is small in size, fits well in the neck for thyroid spectroscopy and is successfully working with the 1.5 tesla whole body Superconducting NMR System available at INMAS.
	Storage Life of an Aluminised HE Composition Author : Narang, R.;Nayak, S.R.;Nair, U.R.;Gharia, J.S. Source : Defence Science Journal ; Vol:43(3) ; 1993 ; pp 263-267 Subject : 620.261 Explosives ;620.1 Material Science and Technology Keywords : High explosive compositions;Thermal stability;Storage life assessment Abstract : "Most high explosive compositions are organic in nature and they tend to undergo slow decomposition during storage under different environmental conditions. The decomposition degrade the molecular stability of the explosive, thereby resulting in reduced performance and service life. The knowledge of decomposition behaviour of the explosive mass determines the storage life of the composition. Hence, change in the chemical stability, sensitivity, mechanical strength and performance are of utmost importance in the prediction of storage life of explosive/ammunitions systems. This paper presents the results on the rate of gas evolution, change in sensitivity, and thermal stability and weight loss of high explosive compositions, viz., Dentex and TNT when exposed to elevated temperature. Based on the collected data, a tentative storage life for the aluminised (Dentex) composition has been computed to be 15 years. The data has been compared with TNT, a standard explosive for assessing the storage life."
	Combustion Behaviour of Advanced Solid Propellants Author : Asthana, S.N.;Mundada, R.B.;Phawade, P.A.;Shrotri, P.G. Source : Defence Science Journal ; Vol:43(3) ; 1993 ; pp 269-273 Subject : 662.3 Propellants;66 Chemical Technology Keywords : Ammonium perchlorate;Propellants;Burning rates;Propellant combustion;AP based compositions Abstract : The study reports the effect of incorporation of Al and ammonium perchlorate (AP) individually and in combination with each other on combustion pattern and specific impulse (Isp) of minimum signature propellants. Incorporation of Al obviates the combustion instability problems; however, it has marginal effect on burning rates. The composition containing AP and zirconium silicate combination gives superior performance; however, its Isp is considerably lower than the composition incorporating 9 per cent AP. A combination of 6 per cent Al gave 20 per cent enhancement in burning rate and 12 s increase in Isp as compared to purely nitramine-based composition, cal-val results also reveal increase in energy output on incorporating AP and Al. Hot stage microscopic and propellant combustion studies indicate occurrence of intense decomposition reaction in case of AP-based compositions.
	Heat Transfer to Peristaltic in a Non Uniform Channel Author : Radhakrishnamacharya, G.;Murty, V. Radhakrishna Source : Defence Science Journal ; Vol:43(3) ; 1993 ; pp 275-280 Subject : 53 Applied Physics Keywords : Viscous incompressible fluid;Sinusoidal waves;Peristaltic wave;Perturbation solution Abstract : The problem of heat transfer for the motion of a viscous incompressible fluid induced by travelling sinusoidal waves has been analytically investigated for a two-dimensional non-uniform channel. Assuming that the wavelength of the peristaltic wave, Lambda, is large in comparison to the mean half width of the channel, d, a perturbation solution in terms of the small parameter, d upon Lambda, has been obtained. Closed form expressions for velocity, temperature and coefficient of heat transfer are presented up to second order. The effects of several pertinent parameters on temperature and heat transfer have been studied and the numerical results obtained are presented.
	Regression Models for Estimation of Human Endurance Time Author : Verma, S.S. Source : Defence Science Journal ; Vol:43(3) ; 1993 ; pp 281-284 Subject : 61 Medical Sciences;612 Physiology Keywords : Regression models;Physiology Abstract : The regression models proposed by different workers for predicting human endurance time have been reviewed critically in respect of their applications for indirect measure of human endurance fitness in strenuous exercise.
	Challenges at the Frontiers of Science and Technology Author : Aatre, V.K. Source : Defence Science Journal ; Vol:43(3) ; 1993 ; pp 285-290 Subject : 355 Defence Sciences Keywords : Armament;Science;Technology Abstract : Abstract not available.