Fractals and the large-scale structure in the Universe

During the last decade it has been argued by some investigators that the distribution of galaxies in the Universe is a fractal. This is contrary to the standard view that the Universe is homogeneous and isotropic on large scales. In this article, the basic concepts of fractals and their characterization are introduced with the help of simple examples. The applications of these concepts in the context of cosmology will be discussed in the second part. A K Mittal is currently a visiting scientist at Harish-Chandra Research Institute, Allahabad, on leave from the University of Allahabad. His research interests include chaos, fractals and their applications, partleularly in cosmology and in weather prodiction. T H Seshadri is at the Department of Physics and Astrophysics, University of Delhi. He is presently on lien from Harish-Chandra Research Institute, Allahabad. Areas of his interest include cosmic microwave background radiation, large scale structures in the Universe and application of fractals in these.     

Fractals and the large-scale structure in the Universe

In Part 1 of this article, we had introduced the reader to some basic concepts of fractals and some operational algorithms to characterize them. We had also pointed out and clarified some common misconceptions about fractals. In this part we apply the fractal concepts to large-scale structures in the Universe. In particular we discuss the claim by some investigators that the distribution of galaxies in the Universe is a fractal. This is contrary to the standard view that the Universe is homogeneous and isotropic on large scales. Also discussed is the controversy as to whether the matter distribution in the Universe is a fractal on large-scales.     

Evaluation of urinary abnormalities in urolithiasis patients: A study from North India

Metabolic abnormalities were investigated in 44 stone patients with first time (group 1) and 56 with 2 times stone formation (group 2), and in 25 normal individuals. 24hr urine was analysed spectrophotometrically for oxalate, calcium, magnesium, citrate, uric acid, phosphate and creatinine. Hypocitraturia and hyperoxaluria were the common abnormalities in the stone formers. Stone patients had significantly higher urinary oxalate, calcium and uric acid and lower phosphate than normal individuals. Citrate/calcium and magnesium/calcium ratio were significantly high in normal individuals than stone formers. Patients in group 2 excreted significantly higher urinary calcium and lower citrate that patients in group 1. Citrate/calcium ratio was higher in group 1 than group 2. Hypocitraturia, hyperoxaluria, hypercalciuria and increased citrate/calcium and magnesium/calcium ratio seem to be an essential risk factor for stone formation. Patients with recurrent stone formation could be distinguished from patients with first time stone formation on the basis of urinary calcium and citrate.     

Silica from ash

A simple chemical process is described for extracting amorphous silica from rice husk.     

Genetics of Obesity

Numerous classical genetic studies have proved that genes are contributory factors for obesity. Genes are directly responsible for obesity associated disorders such as Bardet–Biedl and Prader–Willi syndromes. However, both genes as well as environment are associated with obesity in the general population. Genetic epidemiological approaches, particularly genome-wide association studies, have unraveled many genes which play important roles in human obesity. Elucidation of their biological functions can be very useful for understanding pathobiology of obesity. In the near future, further exploration of obesity genetics may help to develop useful diagnostic and predictive tests for obesity treatment.     

Can High Titres of Anti Tissue Transglutaminase Antibodies Reduce the Need for Intestinal Biopsy for Diagnosis of Celiac Disease?

Traditionally small intestinal biopsy has been considered a gold standard for the diagnosis of celiac disease (CD). But now data has shown that serological markers like anti-tissue-transglutaminase antibodies (tTGA) can be used to make the diagnosis with great sensitivity and specificity. The objective of the present study was to evaluate whether patients with high probability of CD and high titre of tTGA, have a high probability of intestinal damage and may not require biopsy for final diagnosis. All the cases with tTGA levels ≥15 IU/ml and who subsequently underwent biopsy from July 2010 to June 2013 were selected. Histopathological findings graded as per Marsh classification were correlated with serum tTGA levels. Grade 3 lesions were considered diagnostic for the disease. Out of total 731 patients 470 had serum tTGA levels >100 IU/ml and 261 patients had <100 IU/ml. Highest levels of tTGA (219.3 IU/ml) were seen in grade 3c which was >12 times the normal cutoff value. Mean serum tTGA in higher histological grade i.e. 3 (3a, 3b, 3c) was 186.7 IU/ml (>12 times the normal cut off value) as compared to grade 1 which was 108.9 IU/ml (>7 times the normal cut off value). Using a tTGA cutoff value of 70 IU/ml, sensitivity was found to be 83.9% while specificity was 56.10% with an overall accuracy of 77.7%. This study confirms that a small intestinal biopsy is not always necessary for the diagnosis of CD in symptomatic patients with high tTGA levels (>70 IU/ml).