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Dartmouth College

2006

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Articles 121 - 128 of 128

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From Mendel To Molecules: A Brief History Of Evolutionary Genetics, Michael Dietrich Jan 2006

From Mendel To Molecules: A Brief History Of Evolutionary Genetics, Michael Dietrich

Dartmouth Scholarship

No abstract provided.


Transposon Disruption Of The Complex I Nadh Oxidoreductase Gene (Snod) In Staphylococcus Aureus Is Associated With Reduced Susceptibility To The Microbicidal Activity Of Thrombin-Induced Platelet Microbicidal Protein 1, Arnold S. Bayer, Peter Mcnamara, Michael R. Yeaman, Natalie Lucindo, Tiffanny Jones, Ambrose L. Cheung Jan 2006

Transposon Disruption Of The Complex I Nadh Oxidoreductase Gene (Snod) In Staphylococcus Aureus Is Associated With Reduced Susceptibility To The Microbicidal Activity Of Thrombin-Induced Platelet Microbicidal Protein 1, Arnold S. Bayer, Peter Mcnamara, Michael R. Yeaman, Natalie Lucindo, Tiffanny Jones, Ambrose L. Cheung

Dartmouth Scholarship

The cationic molecule thrombin-induced platelet microbicidal protein 1 (tPMP-1) exerts potent activity against Staphylococcus aureus. We previously reported that a Tn551 S. aureus transposon mutant, ISP479R, and two bacteriophage back-transductants, TxA and TxB, exhibit reduced in vitro susceptibility to tPMP-1 (tPMP-1(r)) compared to the parental strain, ISP479C (V. Dhawan, M. R. Yeaman, A. L. Cheung, E. Kim, P. M. Sullam, and A. S. Bayer, Infect. Immun. 65:3293-3299, 1997). In the current study, the genetic basis for tPMP-1(r) in these mutants was identified. GenBank homology searches using sequence corresponding to chromosomal DNA flanking Tn551 mutant strains showed that the fourth gene …


Integration Without Unification: An Argument For Pluralism In The Biological Sciences, Michael Dietrich, Sandra D. Mitchell Jan 2006

Integration Without Unification: An Argument For Pluralism In The Biological Sciences, Michael Dietrich, Sandra D. Mitchell

Dartmouth Scholarship

In this article, we consider the tension between unification and pluralism in biological theory. We begin with a consideration of historical efforts to establish a unified understanding of evolution in the neo-Darwinian synthesis. The fragmentation of the evolutionary synthesis by molecular evolution suggests the limitations of the general unificationist ideal for biology but not necessarily for integrating explanations. In the second half of this article, we defend a specific variety of pluralism that allows for the integration required for explanations of complex phenomena without unification on a large scale.


Using Electron Backscatter Diffraction Patterns To Examine Recrystallization In Polar Ice Sheets, Rachel Obbard, Ian Baker, Katherine Sieg Jan 2006

Using Electron Backscatter Diffraction Patterns To Examine Recrystallization In Polar Ice Sheets, Rachel Obbard, Ian Baker, Katherine Sieg

Dartmouth Scholarship

The fabric of polycrystalline ice is typically described using the c-axis orientation alone, but this is insufficient for a full description of grain orientations in this hexagonal material. Electron backscatter diffraction (EBSD) provides full c- and a-axis orientation of individual grains, and is used here to study Greenland Ice Sheet Project 2 (GISP2) ice specimens from depths of 1551, 1642 and 1745 m. Complete orientation data are used to compare nearest-neighbor relationships to overall fabric and to differentiate between recrystallization mechanisms. Changes in orientation between grains and subgrains in GISP2 specimens were correlated with the appearance of grain boundaries on …


Innate Antiviral Response Targets Hiv-1 Release By The Induction Of Ubiquitin-Like Protein Isg15, Atsushi Okumura, Gengshi Lu, Ian Pitha-Rowe, Paula M. Pitha Jan 2006

Innate Antiviral Response Targets Hiv-1 Release By The Induction Of Ubiquitin-Like Protein Isg15, Atsushi Okumura, Gengshi Lu, Ian Pitha-Rowe, Paula M. Pitha

Dartmouth Scholarship

The goal of this study was to elucidate the molecular mechanism by which type I IFN inhibits assembly and release of HIV-1 virions. Our study revealed that the IFN-induced ubiquitin-like protein ISG15 mimics the IFN effect and inhibits release of HIV-1 virions without having any effect on the synthesis of HIV-1 proteins in the cells. ISG15 expression specifically inhibited ubiquitination of Gag and Tsg101 and disrupted the interaction of the Gag L domain with Tsg101, but conjugation of ISG15 to Gag or Tsg101 was not detected. The inhibition of Gag-Tsg101 interaction was also detected in HIV-1 infected, IFN-treated cells. Elimination …


Brittle Compressive Failure Of Ice: Proportional Straining Vs Proportional Loading, E. M. Schulson, D. Iliescu Jan 2006

Brittle Compressive Failure Of Ice: Proportional Straining Vs Proportional Loading, E. M. Schulson, D. Iliescu

Dartmouth Scholarship

Proportional straining experiments have been performed on columnar-grained S2 fresh- water ice biaxially compressed across the columns at –108C at a strain rate of (4.5 􏰀 1.5) 􏰁 10–3 s–1. The results are compared with those obtained earlier (Iliescu and Schulson, 2004) from the same kind of material deformed to terminal failure under the same conditions, but through proportional loading. The exercise shows that the biaxial strength is practically independent of the path taken, at least under low confinement where Coulombic shear faulting limits terminal failure. First-year sea ice is expected to exhibit the same behavior.


Discovery Of Outlying High-Velocity Oxygen-Rich Ejecta In Cassiopeia A, Robert A. Fesen, Molly C. Hammell, Jon Morse, Roger A. Chevalier, Kazimierz J. Borkowski, Michael A. Dopita, Christopher L. Gerardy, Stephen S. Lawrence, John C. Raymond, Sydney Van Den Bergh Jan 2006

Discovery Of Outlying High-Velocity Oxygen-Rich Ejecta In Cassiopeia A, Robert A. Fesen, Molly C. Hammell, Jon Morse, Roger A. Chevalier, Kazimierz J. Borkowski, Michael A. Dopita, Christopher L. Gerardy, Stephen S. Lawrence, John C. Raymond, Sydney Van Den Bergh

Dartmouth Scholarship

Analysis of broadband HST ACS and WFPC2 images of the young Galactic supernova remnant Cassiopeia A reveals a far larger population of outlying, high-velocity knots of ejecta with a broader range of chemical properties than previously suspected. ACS filte r flux ratios along with follow-up, ground-based spectra are used to investigate some of the kinema tic and chemical properties of these outermost ejecta. In this paper, we concentrate on a ≃ 1.5 sq arcmin region located along the eastern limb of the remnant where numerous outer emission knots are optica lly visible due to an interaction with a local circumstellar …


A Solidification Phenomenon In Random Packings, L. Bowen, R. Lyons, C. Radin, P. Winkler Jan 2006

A Solidification Phenomenon In Random Packings, L. Bowen, R. Lyons, C. Radin, P. Winkler

Dartmouth Scholarship

We prove that uniformly random packings of copies of a certain simply connected figure in the plane exhibit global connectedness at all sufficiently high densities, but not at low densities.