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Biomedical subjects

C R Rao

Publications and source records attributed to C R Rao.

At least 19 recordsLinked to original sources
PubMed2001

A note on Kalman Filter.

The Kalman Filter commonly employed by control engineers and other physical scientists has been successfully used in such diverse areas as the processing of signals in aerospace tracking and underwater sonar, and statistical quality control. More recently, it has been used in some nonengineering applications such as short-term forecasting, time series, survival analysis, and so on. In all of these situations, we have a set of equations governing the true state of a system and another set connecting the observations made at any given time on the system with its true state. The problem is that of predicting the true state of the system at any given time point based on available observations. The solution proposed in the vast literature of the subject depends on the assumptions made on the initial state of the system. In this paper, a method that is independent of the initial state is proposed. This is useful when the a priori information on the initial state is not available. The method is also applicable when some observations are missing.

Journal Article↗
PubMed2000

A note on statistical analysis of shape through triangulation of landmarks.

In an earlier paper, the author jointly with S. Suryawanshi proposed statistical analysis of shape through triangulation of landmarks on objects. It was observed that the angles of the triangles are invariant to scaling, location, and rotation of objects. No distinction was made between an object and its reflection. The present paper provides the methodology of shape discrimination when reflection is also taken into account and makes suggestions for modifications to be made when some of the landmarks are collinear.

Journal Article↗
PubMed2000

Association of Burkitt's lymphoma with the Epstein-Barr virus in two developing countries.

The clinical presentation of Burkitt's lymphoma (BL) and it's association with the Epstein-Barr virus (EBV) varies in different geographic areas, BL in developing countries being "intermediate" between the sporadic and endemic types, both in it's clinical presentation and it's association with EBV, which varies from 25-80%. In this study we have analysed the clinical features, EBV association, subtype and prevalence of the deleted variant of the Latent Membrane Protein-1 (LMP-1) of EBV in forty-two cases from two developing countries- India (n = 25) and Argentina (n = 17). In both countries the abdomen was the site most commonly involved while jaw involvement was rare. EBV was detected by in-situ hybridization using the EBER-1 RNA probe. 47% of cases from Argentina and 80% of cases from India were EBER positive. EBV typing using EBNA-3C primers showed a predominance of Type A in both countries (India-13/16 and Argentina-(7/8)). The 30bp deletion of the LMP-1 gene was detected in all evaluated cases from Argentina while the wild type of the gene was seen in all the evaluable Indian cases. Our study highlights the similarities and differences in the clinical presentation and EBV association of BL in two developing countries and also indicates that the subtype of EBV and prevalence of the LMP-1 deletion may reflect the predominant subtype in a particular population.

Adolescent↗
PubMed1999

The simultaneous estimation of the number of signals and frequencies of multiple sinusoids when some observations are missing: I. Asymptotics.

The problem of simultaneous estimation of the number of signals and frequencies of multiple sinusoids is considered in the case when some observations are missing. The number of signals is estimated with an information theoretic criterion, and the frequencies are estimated with eigenvariation linear prediction. The strong consistency of the estimates of the number of signals and the frequencies is established and the rate of convergence of these estimates is provided. Besides, the limiting distributions of various estimates are given.

Journal Article↗
PubMed1999

Parotid tuberculosis simulating malignancy.

An interesting case of parotid tumour simulating malignancy is reported. The rarity of this lesion and the associated clinical and diagnostic problems are emphasized together with the relevant literature.

Adult↗
PubMed1998

Geometry of circular vectors and pattern recognition of shape of a boundary.

This paper deals with pattern recognition of the shape of the boundary of closed figures on the basis of a circular sequence of measurements taken on the boundary at equal intervals of a suitably chosen argument with an arbitrary starting point. A distance measure between two boundaries is defined in such a way that it has zero value when the associated sequences of measurements coincide by shifting the starting point of one of the sequences. Such a distance measure, which is invariant to the starting point of the sequence of measurements, is used in identification or discrimination by the shape of the boundary of a closed figure. The mean shape of a given set of closed figures is defined, and tests of significance of differences in mean shape between populations are proposed.

Mathematics↗
PubMed1998

Statistical analysis of shape through triangulation of landmarks: A study of sexual dimorphism in hominids.

Two objects with homologous landmarks are said to be of the same shape if the configuration of landmarks of one object can be exactly matched with that of the other by translation, rotation/reflection, and scaling. In an earlier paper, the authors proposed statistical analysis of shape by considering logarithmic differences of all possible Euclidean distances between landmarks. Tests of significance for differences in the shape of objects and methods of discrimination between populations were developed with such data. In the present paper, the corresponding statistical methodology is developed by triangulation of the landmarks and by considering the angles as natural measurements of shape. This method is applied to the study of sexual dimorphism in hominids.

Animals↗
PubMed1996

Statistical analysis of shape of objects based on landmark data.

Two objects with homologous landmarks are said to be of the same shape if the configurations of landmarks of one object can be exactly matched with that of the other by translation, rotation/reflection, and scaling. The observations on an object are coordinates of its landmarks with reference to a set of orthogonal coordinate axes in an appropriate dimensional space. The origin, choice of units, and orientation of the coordinate axes with respect to an object may be different from object to object. In such a case, how do we quantify the shape of an object, find the mean and variation of shape in a population of objects, compare the mean shapes in two or more different populations, and discriminate between objects belonging to two or more different shape distributions. We develop some methods that are invariant to translation, rotation, and scaling of the observations on each object and thereby provide generalizations of multivariate methods for shape analysis.

Face↗
PubMed1996

Magliant melanoma of the oral cavity: report of 14 cases from a regional cancer centre.

Fourteen patients with oral mucosal malignant melanomas seen at a regional cancer centre over a 10-year period were analysed. All the patients presented with symptoms of short duration, with extensive local disease at initial evaluation in 11 patients. The palate was the commonest site involved. Ten patients had regional nodal disease and of these four also had distant metastases to the liver and/or the lung. Coincidental melanosis was identified clinically in three patients and histologically confirmed in two patients. Only four patients underwent radical surgery. Of the five patients who received DTIC-based chemotherapy, only one achieved a complete response. No significant correlation between stage of the disease at presentation, histological features or type of treatment and survival could be seen as the number of cases is small.

Adult↗
PubMed1996

Primary central nervous system lymphoma a report of nine cases.

Primary Central Nervous System Lymphoma (PCNSL) is a rare neoplasm of B cell origin and constitute less than 1% of Non-Hodgkin's lymphoma (NHL). Histology is mainly of high grade and intermediate type. Although NHL is known to be highly sensitive to both irradiation and cytotoxic drugs, being a curable malignancy, the therapeutic results remain disappointing. Clinical observations on nine cases of PCNSL seen in one of the major cancer centres in India is presented in this paper. Radiotherapy combined with Chemotherapy although yielded encouraging initial response in these patients, the long term response was unsatisfactory with median survival for these patients being only 19 months. This warrants an alternative therapeutic approach to improve the dismal prognosis of PCNSL.

Adult↗
PubMed1995

Cytogenetic and viral studies in nasopharyngeal carcinomas in patients of Indian origin.

Four cases of undifferentiated nasopharyngeal carcinomas (NPC) (grade III-IV) in patients of Indian origin were investigated for specific chromosome markers and evidence of Epstein-Barr virus (EBV) positivity. Abnormalities involving chromosome #3, like del (3) (p24-pter) and 3q+(q27-qter) were found in these patients, similar to earlier reports in patients of Chinese and Kenyan origin2,4,13 who however were EBV positive, unlike the patients in this study who were EBV negative. Implications of the cytogenetic and serological data in Indian patients with NPC, available for the first time, may throw some light on the etiology of the disease in this ethnic group where nasopharyngeal carcinoma is also endemic.

Antibodies, Viral↗
PubMed1995

Spinal cord compression by primary non-Hodgkin's lymphoma.

Epidural Cord Compression (ECC) by primary lymphomas is rare entity and constitutes less than 3% of total malignant lymphoma with Non-Hodgkin's Lymphoma (NHL), diffuse large cell type being the most common histological subtype. In this paper 16 cases of primary NHL with cord compression seen at the Department of Medical Oncology, during the period 1988-1990 are reviewed. At presentation all patients had undergone Laminectomy with decompression of epidural mass. The histological diagnosis of NHL was subclassified according to the International working formulation and was evaluated for disease process elsewhere in the body. All patients with ECC by lymphoma received high dose steroids with concurrent Radiotherapy (local) and combination Chemotherapy. These patients had longer duration of neurological deficit prior to treatment had poor response. After 6 courses of chemotherapy 50% of the patients had complete neurological recovery (CR), 31% had partial neurological recovery (PR) and in 19% there was no neurological recovery (NR).

Adolescent↗
PubMed1994

Adult paratesticular sarcomas: a report of eight cases.

Eight adult paratesticular sarcomas seen at a Regional Cancer Centre over a 7-year period are described. There were three cases of rhabdomyosarcoma (RMS), three cases of leiomyosarcoma (LMS), and two cases of liposarcoma (LS). The RMS occurred in a younger age group (3rd decade) than the LMS and LS (6th and 7th decades). Most of our patients presented with advanced disease after orchiectomy at other hospitals, three with recurrent or residual disease and four with metastasis. The single patient with RMS who received intensive adjuvant therapy is free of disease at 84 months in spite of the advanced stage at presentation. All three patients with LMS had an unfavourable clinical course. Both the patients with LS had well differentiated (WD) tumours and presented with recurrences, one over several years, following initial local excisions. The necessity for early adequate surgical and adjuvant therapy and the need for a uniform treatment policy are discussed.

Adult↗