Proceedings of The National Academy of Sciences, 2004
his report describes the design and operation of a waveguide, an optical switch, and an evanescen... more his report describes the design and operation of a waveguide, an optical switch, and an evanescent coupler in which both the light-guiding and cladding structures are liquids flowing at low Reynolds number (Re 5-500) (1) in microchannels fabricated in poly(dimethylsiloxane) (PDMS). The liquidliquid interfaces in these systems (liquid-coreliquid-cladding (liqliq) waveguides) are optically smooth at low Re flow; modest rough- ness
Proceedings of the National Academy of Sciences, 2004
This report describes the manipulation of light in waveguides that comprise a liquid core and a l... more This report describes the manipulation of light in waveguides that comprise a liquid core and a liquid cladding (liqÍžliq waveguide). These waveguides are dynamic: Their structure and function depend on a continuous, laminar flow of the core and cladding liquids. Because they are dynamic, they can be reconfigured and adapted continuously in ways that are not possible with solid-state waveguides. The liquids are introduced into the channels of a microfluidic network designed to sandwich the flowing core liquid between flowing slabs of the cladding fluid. At low and moderate Reynolds numbers, flow is laminar, and the liqÍžliq interfaces are optically smooth. Small irregularities in the solid walls of the channels do not propagate into these interfaces, and liqÍžliq waveguides therefore exhibit low optical loss because of scattering. Manipulating the rate of flow and the composition of the liquids tunes the characteristics of these optical systems.
Analyses investigating low frequency variants have the potential for explaining additional geneti... more Analyses investigating low frequency variants have the potential for explaining additional genetic heritability of many complex human traits. However, the natural frequencies of rare variation between human populations strongly confound genetic analyses. We have applied a novel collapsing method to identify biological features with low frequency variant burden differences in thirteen populations sequenced by the 1000 Genomes Project. Our flexible collapsing tool utilizes expert biological knowledge from multiple publicly available database sources to direct feature selection. Variants were collapsed according to genetically driven features, such as evolutionary conserved regions, regulatory regions genes, and pathways. We have conducted an extensive comparison of low frequency variant burden differences (MAF,0.03) between populations from 1000 Genomes Project Phase I data. We found that on average 26.87% of gene bins, 35.47% of intergenic bins, 42.85% of pathway bins, 14.86% of ORegAnno regulatory bins, and 5.97% of evolutionary conserved regions show statistically significant differences in low frequency variant burden across populations from the 1000 Genomes Project. The proportion of bins with significant differences in low frequency burden depends on the ancestral similarity of the two populations compared and types of features tested. Even closely related populations had notable differences in low frequency burden, but fewer differences than populations from different continents. Furthermore, conserved or functionally relevant regions had fewer significant differences in low frequency burden than regions under less evolutionary constraint. This degree of low frequency variant differentiation across diverse populations and feature elements highlights the critical importance of considering population stratification in the new era of DNA sequencing and low frequency variant genomic analyses.
The effect of microgravity on the growth of silica nanoparticles via the sol-gel route is profoun... more The effect of microgravity on the growth of silica nanoparticles via the sol-gel route is profound. In four different recipes that typically produce silica nanoparticles in unit gravity, low-density gel structures were instead formed in microgravity. These observations suggest that microgravity reduces the particle growth rate, allowing unincorporated species to form aggregates and ultimately gel. Hence microgravity favors the formation of more rarefied structures, providing a bias toward diffusion-limited aggregation. Moreover, these results add to evidence that the growth of silica nanoparticles occurs not simply through monomer addition but by the attachment of smaller primary particles and aggregates.
June 2008 Members of Congress: On behalf of the National Science and Technology Council, the US C... more June 2008 Members of Congress: On behalf of the National Science and Technology Council, the US Climate Change Science Program (CCSP) is pleased to transmit to the President and the Congress this Synthesis and Assessment Product (SAP), The Effects of Climate ...
The role of ozone in the troposphere is of utmost importance as it can affect atmospheric composi... more The role of ozone in the troposphere is of utmost importance as it can affect atmospheric composition and radiative properties. Ozone (O3) is the primary source of hydroxyl radicals, which in turn are responsible to initiate most of the oxidation processes in the atmosphere. In the upper troposphere, ozone is a greenhouse gas that plays a key role in radiative forcing and potential climate change [Wang et al., 1980, 1993; Hansen et al., 2002, Thompson et al., 2002]. Previous studies have shown the significance of gravity and Rossby wave activity in the formation and transport of ozone and other constituents, due to vertical displacement and quasi-horizontal transport of material surfaces, respectively [Danielsen et al., 1991; Reid and Vaughan, 1991; Tsuda et al., 1994; Teitelbaum et al.,1996; Pierce and Grant, 1998; Grant et al., 1998; Fujiwara et al.,1998, Stone, 2006 and Thompson et al., 2007, 2011]. Based on this approach, Thompson et al. (2007, 2011) proposes 4 major dynamical o...
Proceedings of The National Academy of Sciences, 2004
his report describes the design and operation of a waveguide, an optical switch, and an evanescen... more his report describes the design and operation of a waveguide, an optical switch, and an evanescent coupler in which both the light-guiding and cladding structures are liquids flowing at low Reynolds number (Re 5-500) (1) in microchannels fabricated in poly(dimethylsiloxane) (PDMS). The liquidliquid interfaces in these systems (liquid-coreliquid-cladding (liqliq) waveguides) are optically smooth at low Re flow; modest rough- ness
Proceedings of the National Academy of Sciences, 2004
This report describes the manipulation of light in waveguides that comprise a liquid core and a l... more This report describes the manipulation of light in waveguides that comprise a liquid core and a liquid cladding (liqÍžliq waveguide). These waveguides are dynamic: Their structure and function depend on a continuous, laminar flow of the core and cladding liquids. Because they are dynamic, they can be reconfigured and adapted continuously in ways that are not possible with solid-state waveguides. The liquids are introduced into the channels of a microfluidic network designed to sandwich the flowing core liquid between flowing slabs of the cladding fluid. At low and moderate Reynolds numbers, flow is laminar, and the liqÍžliq interfaces are optically smooth. Small irregularities in the solid walls of the channels do not propagate into these interfaces, and liqÍžliq waveguides therefore exhibit low optical loss because of scattering. Manipulating the rate of flow and the composition of the liquids tunes the characteristics of these optical systems.
Analyses investigating low frequency variants have the potential for explaining additional geneti... more Analyses investigating low frequency variants have the potential for explaining additional genetic heritability of many complex human traits. However, the natural frequencies of rare variation between human populations strongly confound genetic analyses. We have applied a novel collapsing method to identify biological features with low frequency variant burden differences in thirteen populations sequenced by the 1000 Genomes Project. Our flexible collapsing tool utilizes expert biological knowledge from multiple publicly available database sources to direct feature selection. Variants were collapsed according to genetically driven features, such as evolutionary conserved regions, regulatory regions genes, and pathways. We have conducted an extensive comparison of low frequency variant burden differences (MAF,0.03) between populations from 1000 Genomes Project Phase I data. We found that on average 26.87% of gene bins, 35.47% of intergenic bins, 42.85% of pathway bins, 14.86% of ORegAnno regulatory bins, and 5.97% of evolutionary conserved regions show statistically significant differences in low frequency variant burden across populations from the 1000 Genomes Project. The proportion of bins with significant differences in low frequency burden depends on the ancestral similarity of the two populations compared and types of features tested. Even closely related populations had notable differences in low frequency burden, but fewer differences than populations from different continents. Furthermore, conserved or functionally relevant regions had fewer significant differences in low frequency burden than regions under less evolutionary constraint. This degree of low frequency variant differentiation across diverse populations and feature elements highlights the critical importance of considering population stratification in the new era of DNA sequencing and low frequency variant genomic analyses.
The effect of microgravity on the growth of silica nanoparticles via the sol-gel route is profoun... more The effect of microgravity on the growth of silica nanoparticles via the sol-gel route is profound. In four different recipes that typically produce silica nanoparticles in unit gravity, low-density gel structures were instead formed in microgravity. These observations suggest that microgravity reduces the particle growth rate, allowing unincorporated species to form aggregates and ultimately gel. Hence microgravity favors the formation of more rarefied structures, providing a bias toward diffusion-limited aggregation. Moreover, these results add to evidence that the growth of silica nanoparticles occurs not simply through monomer addition but by the attachment of smaller primary particles and aggregates.
June 2008 Members of Congress: On behalf of the National Science and Technology Council, the US C... more June 2008 Members of Congress: On behalf of the National Science and Technology Council, the US Climate Change Science Program (CCSP) is pleased to transmit to the President and the Congress this Synthesis and Assessment Product (SAP), The Effects of Climate ...
The role of ozone in the troposphere is of utmost importance as it can affect atmospheric composi... more The role of ozone in the troposphere is of utmost importance as it can affect atmospheric composition and radiative properties. Ozone (O3) is the primary source of hydroxyl radicals, which in turn are responsible to initiate most of the oxidation processes in the atmosphere. In the upper troposphere, ozone is a greenhouse gas that plays a key role in radiative forcing and potential climate change [Wang et al., 1980, 1993; Hansen et al., 2002, Thompson et al., 2002]. Previous studies have shown the significance of gravity and Rossby wave activity in the formation and transport of ozone and other constituents, due to vertical displacement and quasi-horizontal transport of material surfaces, respectively [Danielsen et al., 1991; Reid and Vaughan, 1991; Tsuda et al., 1994; Teitelbaum et al.,1996; Pierce and Grant, 1998; Grant et al., 1998; Fujiwara et al.,1998, Stone, 2006 and Thompson et al., 2007, 2011]. Based on this approach, Thompson et al. (2007, 2011) proposes 4 major dynamical o...
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Papers by Daniel Wolfe