Discussion: The Dantzig selector: Statistical estimation when pp is much larger than nn

Discussion of ``The Dantzig selector: Statistical estimation when $p$ is much larger than $n$'' [math/0506081]Comment: Published in at http://dx.doi.org/10.1214/009053607000000442 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

Directionally asymmetric self-assembly of cadmium sulfide nanotubes using porous alumina nanoreactors: Need for chemohydrodynamic instability at the nanoscale

We explore nanoscale hydrodynamical effects on synthesis and self-assembly of cadmium sulfide nanotubes oriented along one direction. These nanotubes are synthesized by horizontal capillary flow of two different chemical reagents from opposite directions through nanochannels of porous anodic alumina which are used primarily as nanoreactors. We show that uneven flow of different chemical precursors is responsible for directionally asymmetric growth of these nanotubes. On the basis of structural observations using scanning electron microscopy, we argue that chemohydrodynamic convective interfacial instability of multicomponent liquid-liquid reactive interface is necessary for sustained nucleation of these CdS nanotubes at the edges of these porous nanochannels over several hours. However, our estimates clearly suggest that classical hydrodynamics cannot account for the occurrence of such instabilities at these small length scales. Therefore, we present a case which necessitates further investigation and understanding of chemohydrodynamic fluid flow through nanoconfined channels in order to explain the occurrence of such interfacial instabilities at nanometer length scales.Comment: 26 pages, 6 figures; http://www.iiserpune.ac.in/researchhighlight

Discussion: The Dantzig Selector: Statistical Estimation When \u3cem\u3ep\u3c/em\u3e is Much Larger Than \u3cem\u3en\u3c/em\u3e

Professors Candès and Tao are to be congratulated for their innovative and valuable contribution to high-dimensional sparse recovery and model selection. The analysis of vast data sets now commonly arising in scientific investigations poses many statistical challenges not present in smaller scale studies. Many of these data sets exhibit sparsity where most of the data corresponds to noise and only a small fraction is of interest. The needs of this research have excited much interest in the statistical community. In particular, high-dimensional model selection has attracted much recent attention and has become a central topic in statistics. The main difficulty of such a problem comes from collinearity between the predictor variables. It is clear from the geometric point of view that the collinearity increases as the dimensionality grows

Bioconversion of ferulic acid and 4-vinylguaiacol by a white-rot fungus isolated from decaying wood

A white rot fungus isolated from decaying wood was investigated for its ability to convert ferulic acid to various valuable products. The fungus is able to convert ferulic acid to 4-vinylguaiacol, which is then metabolized further to acetovanillone. Both products have potential use in the chemical manufacturing and pharmaceutical industries and these results contribute to our knowledge of the biotransformation of ferulic acid

Determination of ferulic acid and related compounds by thin layer chromatography

The analysis of certain phenolic compounds from plants, and their chemical transformation with microorganisms or isolated enzymes, has application in the food and pharmaceutical industry. The rapid quantitative estimation of ferulic acid by thin layer chromatography is described by measurementof the area of the obtained spots. Furthermore, the qualitative analysis of a number of related phenolics, some of which are transformation products of ferulic acid, is achieved on thin layer chromatographic plates by the use of different spray reagent