22,181 research outputs found
Discussion: The Dantzig selector: Statistical estimation when is much larger than
Discussion of ``The Dantzig selector: Statistical estimation when is much
larger than '' [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
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Response to letter: contribution of serum ethanol concentration to the osmol gap: a prospective volunteer study.
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
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
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
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