On the Existence of Epipolar Matrices

This paper considers the foundational question of the existence of a fundamental (resp. essential) matrix given m point correspondences in two views. We present a complete answer for the existence of fundamental matrices for any value of m. We disprove the widely held beliefs that fundamental matrices always exist whenever \(m \le 7\). At the same time, we prove that they exist unconditionally when \(m \le 5\). Under a mild genericity condition, we show that an essential matrix always exists when \(m \le 4\). We also characterize the six and seven point configurations in two views for which all matrices satisfying the epipolar constraint have rank at most one.     

Retinopathy of prematurity: incidence and risk factors

OBJECTIVE: To determine the incidence of Retinopathy of Prematurity (ROP) in high risk babies admitted to the neonatal unit and to study risk factors for it's development. DESIGN: Prospective cohort study. SETTING: Level II Neonatal Intensive Care Unit. SUBJECTS: 100 babies admitted to the neonatal unit during a 4 year period who were below 1500 g or whose gestation was < or = 34 weeks. METHODS: Examination of the eye was done in the neonatal unit or in the neonatal follow up clinic by an Ophthalmologist by indirect Ophthalmoscopy at 4-6 weeks postnatal age. RESULTS: The incidence of ROP was 46%. Of the 100 babies screened, 21 had stage I, 14 had stage II, 8 had stage III and 3 had stages IV and V. The incidence of ROP was 73.3% among < 1000 g babies and 47.3% among < 1500 g babies. The incidence of ROP among 28-29 weeks, 30-31 weeks and 32-33 weeks babies was 83%, 60% and 50%, respectively. The maximum stage of ROP developed between 37-42 weeks post conceptional age in 69% subjects. On univariate analysis, gestation < or = 32 weeks, anemia, Blood transfusions, apnea and exposure to oxygen significantly increased the risk of developing ROP. On multivariate logistic regression analysis, anemia and duration of oxygen therapy were the significant independent predictors of development of ROP. Nine of the 46 babies underwent cryotherapy for threshold ROP. CONCLUSION: The incidence of ROP among high risk babies is significant and duration of oxygen therapy and anemia are independent factors predicting the development of ROP. All high risk babies should be screened for ROP. Cryotherapy is a relatively simple procedure which can be done in the neonatal unit.     

Parameter estimation in stochastic mammogram model by heuristic optimization techniques.

The appearance of disproportionately large amounts of high-density breast parenchyma in mammograms has been found to be a strong indicator of the risk of developing breast cancer. Hence, the breast density model is popular for risk estimation or for monitoring breast density change in prevention or intervention programs. However, the efficiency of such a stochastic model depends on the accuracy of estimation of the model's parameter set. We propose a new approach-heuristic optimization-to estimate more accurately the model parameter set as compared to the conventional and popular expectation-maximization (EM) algorithm. After initial segmentation of a given mammogram, the finite generalized Gaussian mixture (FGGM) model is constructed by computing the statistics associated with different image regions. The model parameter set thus obtained is estimated by particle swarm optimization (PSO) and evolutionary programming (EP) techniques, where the objective function to be minimized is the relative entropy between the image histogram and the estimated density distributions. When our heuristic approach was applied to different categories of mammograms from the Mini-MIAS database, it yielded lower floor of estimation error in 109 out of 112 cases (97.3 %), and 101 out of 102 cases (99.0%), for the number of image regions being five and eight, respectively, with the added advantage of faster convergence rate, when compared to the EM approach. Besides, the estimated density model preserves the number of regions specified by the information-theoretic criteria in all the test cases, and the assessment of the segmentation results by radiologists is promising.     

Gellan gum for reducing oil uptake in sev,a legume based product during deep-fat frying

Gellan gum, a high molecular weight anionic linear polysaccharide produced by pure culture fermentation from Sphingomonas paucimobilis ATCC 31461 is used in a variety of food applications that are based on its unique gelling profile. The present work reports on the effective use of gellan gum on the oil uptake of a traditional Indian deep-fat fried product, sev that is based on chickpea flour. The effect of addition of gellan gum at 0.25–0.75% (w/w) (based on chickpea flour) on the dough texture, and that of the sev prepared was also evaluated using TA.XT2i Texture Analyzer. Addition of gellan gum at 0.25% (w/w) markedly reduced the oil content in the sev from 37.02% in the control to 27.91%. The reduction in oil content beyond 0.25% gellan gum addition was not significant (P = 0.05). Furthermore, while addition of gellan gum significantly altered the texture of dough, it did not significantly affect the texture of sev (P = 0.05). Addition of 0.25% gellan gum in combination with sodium alginate (0.25–1.00%), carboxymethylcellulose (0.25–1.00%) or soy protein isolate (2.5–10.0%) did not affect oil uptake significantly (P = 0.05) as compared to that prepared by the addition of 0.25% gellan gum alone.     

Usability study of digital libraries: ACM, IEEE-CS, NCSTRL, NDLTD

If digital libraries are to be used effectively, their user interfaces should be tested and enhanced. We observed 48 participants as they worked with the following digital libraries: ACM, IEEE-CS, NCSTRL, and NDLTD. We discuss how the features of these digital libraries influence the subjects’ efforts to perform search and retrieval tasks. Data analysis indicates that the IEEE-CS digital library was rated the best overall and NDLTD had the best search time. We present user recommendations and propose a taxonomy of features that we believe are essential for the design of future digital libraries. Noteworthy is the observation that users’ judgements on the importance of different features varied widely between the beginning and end of their test sessions. Received: 15 December 1997 / Revised: June 1999     

Detection and characterization of Salmonella associated with tropical seafood

The prevalence of Salmonella in seafood samples collected from the southwest coast of India was studied by conventional culture and by a DNA based molecular technique, polymerase chain reaction (PCR). While conventional culture techniques detected Salmonella in only 20 out of the 100 samples analyzed, direct enrichment lysate PCR detected 52 as positive for Salmonella. A set of three different PCR primers viz., hns, invA and invE were used. It was observed that hns primer detected Salmonella in a significantly higher number of samples. Fourteen out of nineteen isolates belonged to serovar S. enterica Weltevreden. S. Weltevreden isolates were genotyped yielding 4 different patterns both by RAPD and ERIC-PCR but when combined, the overall results discriminated the isolates of S. Weltevreden into 6 different types. This suggests that genetically diverse Salmonella Weltevreden are prevalent in seafood.     

Purification of Lycopene by Reverse Phase Chromatography

This work investigates the potential of various hydrophobic matrices for the separation and purification of lycopene from microbial biomass obtained from fermentation using Blakeslea trispora. The lycopene purification method was developed in two steps. In the first step, carotenoids were extracted from the biomass of B. trispora with petroleum ether/acetone (1:1). In the second step, this partially purified carotenoid extract was further purified by reverse phase chromatography technique. Various binding conditions were studied to achieve maximum amount of lycopene bound onto the chromatographic matrices. Column studies on the elution conditions of lycopene using linear and step gradient method were investigated. Purification of lycopene using packed bed column by reverse phase chromatography matrix HP20 was carried out using step gradient of 55% isopropyl alcohol in acetone followed by 65% isopropyl alcohol in acetone. The purity and recovery of lycopene was checked using Knauer high-performance liquid chromatography (HPLC) system. A 89% recovery of lycopene of HPLC purity 95% was achieved with substantial success. Proton magnetic resonance of the purified sample showed close resemblance with the chemical shifts (δ values) of the standard lycopene.     

Evaluation of debittered and germinated fenugreek (Trigonella foenum graecum L.) seed flour on the chemical characteristics,biological activities,and sensory profile of fortified bread

Germination of fenugreek seed showed better nutraceutical profile as evaluated by in vivo (oral glucose tolerance and acute antihypertriglyceridemic tests) on rats and in vitro DPPH and enzyme inhibition assays (α‐glucosidase, lipase, and lipoxygenase). Attempts were made to develop debittered and germinated fenugreek seed flour (DGFSF) by soaking in acesulfame (0.25%, 8 hr), curd (1:1 in water, 8 hr) and sucrose (5%, 8 hr) solution at 1:4 (wt/vol) ratio for debittering and then germinated, of which curd showed the maximum extent of debittering. The effect of substitution of wheat flour with 5, 10, 15, and 20% (wt/wt) of DGFSF on chemical characteristics and sensory properties was investigated; 10% fortified bread was organoleptically acceptable and had enhanced protein and fiber contents. Fortification increased the bulk density and crumb firmness, decreased the specific loaf volume, and darkened the crumb color. Glycemic index of the bread decreased with 10% DGFSF, which is indicative of desirable health benefits.

Practical applications

Fenugreek seeds are major constituent of Indian spices, bitter to taste and possess various medicinal properties. These seeds are an excellent source of dietary fiber and protein. Although incorporated into traditional foods, its bitterness limits its wide usage. In India, soaking and germination of seeds in water or curd was practiced traditionally since ancient days. Germination and debittering improved antioxidant activity, and various in vitro and in vivo bioactivities. Incorporation of debittered flour improved the polyphenolic, protein, and dietary fiber contents in bread which in turn demonstrated reduced rate of in vitro starch digestibility or lower glycemic index