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Dartmouth Scholarship

2003

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Resonant Emergence Of Global And Local Spatiotemporal Order In A Nonlinear Field Model, Marcelo Gleiser, Rafael C. Howell Dec 2003

Resonant Emergence Of Global And Local Spatiotemporal Order In A Nonlinear Field Model, Marcelo Gleiser, Rafael C. Howell

Dartmouth Scholarship

We investigate the nonequilibrium evolution of a scalar field in (2+1) dimensions. The field is set in a double-well potential in contact (open) or not (closed) with a heat bath. For closed systems, we observe the synchronized emergence of coherent spatiotemporal configurations, identified with oscillons. This initial global ordering degenerates into localized order until all oscillons disappear. We show that the synchronization is driven by resonant parametric oscillations of the field’s zero mode and that local ordering is only possible outside equipartition. None of these orderings occur for open systems.

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Objectivity, Information, And Maxwell's Demon, Steven Weinstein Dec 2003

Objectivity, Information, And Maxwell's Demon, Steven Weinstein

Dartmouth Scholarship

This paper examines some common measures of complexity, structure, and information, with an eye toward understanding the extent to which complexity or information‐content may be regarded as objective properties of individual objects. A form of contextual objectivity is proposed which renders the measures objective, and which largely resolves the puzzle of Maxwell's Demon.

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Interleukin-10 And Pathogenesis Of Murine Ocular Toxoplasmosis, Fangli Lu, Shiguang Huang, Lloyd H. Kasper Dec 2003

Interleukin-10 And Pathogenesis Of Murine Ocular Toxoplasmosis, Fangli Lu, Shiguang Huang, Lloyd H. Kasper

Dartmouth Scholarship

To understand the role of interleukin-10 (IL-10) in ocular toxoplasmosis, we compared C57BL/6 (B6) and BALB/c background mice lacking a functional IL-10 gene (IL-10(-/-)) and B6 transgenic mice expressing IL-10 under the control of the IL-2 promoter. Increased cellular infiltration and necrosis were observed in the eye tissue of IL-10(-/-) mice of both the B6 and BALB/c backgrounds with associated changes in the levels of cytokines in serum. In contrast, there was no evidence of necrosis in the eye tissue from IL-10 transgenic mice following parasite exposure. Our results demonstrate that IL-10 is important in the regulation of inflammation during …

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Parallaxes And Distance Estimates For 14 Cataclysmic Variable Stars, John R. Thorstensen Dec 2003

Parallaxes And Distance Estimates For 14 Cataclysmic Variable Stars, John R. Thorstensen

Dartmouth Scholarship

I used the 2.4 m Hiltner Telescope at MDM Observatory in an attempt to measure trigonometric parallaxes for 14 cataclysmic variable stars. Techniques are described in detail. In the best cases the parallax uncertainties are below 1 mas, and significant parallaxes are found for most of the program stars. A Bayesian method that combines the parallaxes together with proper motions and absolute magnitude constraints is developed and used to derive distance estimates and confidence intervals. The most precise distance derive here is for WZ Sge, for which I find 43: 3.1:6 1:5 pc. Six Luyten Half-Second stars with previous precise …

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Antipredator Behavior And Physiology Determine Lestes Species Turnover Along The Pond-Permanence Gradient, Robby Stoks, Mark A. Mcpeek Dec 2003

Antipredator Behavior And Physiology Determine Lestes Species Turnover Along The Pond-Permanence Gradient, Robby Stoks, Mark A. Mcpeek

Dartmouth Scholarship

Identifying key traits that shape trade-offs that restrict species to only a subset of environmental gradients is crucial to understanding and predicting species turnover. Previous field experiments have shown that larvae of Lestes damselfly species segregate along the entire gradient of pond permanence and predator presence and that differential predation risk and life history constraints together shape their distribution. Here, we report laboratory experiments that identify key differences in behavior and physiology among species that structure their distributions along this gradient. The absence of adaptive antipredator behavioral responses against large dragonfly larvae and fish of Lestes dryas, the only species …

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Disulfide Bond Formation Involves A Quinhydrone-Type Charge–Transfer Complex, James Regeimbal, Stefan Gleiter, Bernard L. Trumpower, Chang-Ang Yu Nov 2003

Disulfide Bond Formation Involves A Quinhydrone-Type Charge–Transfer Complex, James Regeimbal, Stefan Gleiter, Bernard L. Trumpower, Chang-Ang Yu

Dartmouth Scholarship

The chemistry of disulfide exchange in biological systems is well studied. However, the detailed mechanism of how oxidizing equivalents are derived to form disulfide bonds in proteins is not clear. In prokaryotic organisms, it is known that DsbB delivers oxidizing equivalents through DsbA to secreted proteins. DsbB becomes reoxidized by reducing quinones that are part of the membrane-bound electron-transfer chains. It is this quinone reductase activity that links disulfide bond formation to the electron transport system. We show here that purified DsbB contains the spectral signal of a quinhydrone, a charge-transfer complex consisting of a hydroquinone and a quinone in …

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Incommensurate Spin Density Waves In Iron Aluminides, D. R. Noakes, A. S. Arrott, M. G. Belk, S. C. Deevi Nov 2003

Incommensurate Spin Density Waves In Iron Aluminides, D. R. Noakes, A. S. Arrott, M. G. Belk, S. C. Deevi

Dartmouth Scholarship

Neutron diffraction in Fe(Al) reveals incommensurate spin density waves (SDWs) in alloys known to be spin glasses. The wave vectors for crystals of Fe(34Al), Fe(40Al), and Fe(43Al) show n varying from 11 to 6 for →q=2π(h±1/n,k±1/n,l±1/n)/a0, where (h,k,l) and a0 characterize the parent bcc lattice of the CsCl structure. The magnetic reflections are present far above the spin-glass freezing temperatures. These SDWs keep the spins on nearest-neighbor Fe atoms close to parallel, in contrast with SDWs in Cr, which keep nearest-neighbor spins close to antiparallel.

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Redshift-Distance Survey Of Early-Type Galaxies: Spectroscopic Data, G. Wegner, M. Bernardi, C. N. A. Willmer, L. N. Da Costa Nov 2003

Redshift-Distance Survey Of Early-Type Galaxies: Spectroscopic Data, G. Wegner, M. Bernardi, C. N. A. Willmer, L. N. Da Costa

Dartmouth Scholarship

We present central velocity dispersions and Mg2 line indices for an all-sky sample of ~1178 elliptical and S0 galaxies, of which 984 had no previous measures. This sample contains the largest set of homogeneous spectroscopic data for a uniform sample of elliptical galaxies in the nearby universe. These galaxies were observed as part of the ENEAR project, designed to study the peculiar motions and internal properties of the local early-type galaxies. Using 523 repeated observations of 317 galaxies obtained during different runs, the data are brought to a common zero point. These multiple observations, taken during the many runs …

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Converting Plant Biomass To Fuels And Commodity Chemicals In South Africa: A Third Chapter?, L R. Lynd, H H Von Blottnitz, B Tait, J De Boer, I S. Pretorius, K Rumbold, W H. Van Zyl Nov 2003

Converting Plant Biomass To Fuels And Commodity Chemicals In South Africa: A Third Chapter?, L R. Lynd, H H Von Blottnitz, B Tait, J De Boer, I S. Pretorius, K Rumbold, W H. Van Zyl

Dartmouth Scholarship

There have been two distinct chapters in the history of converting cellulosic biomass to fuels and commodity chemicals in South Africa. The first chapter, fromthe late 1970s to the early 1990s, involved some of the most active research and development efforts of their kind anywhere in the world. Thereafter, during the second chapter, there has been very little activity in the field in South Africa while there has been an unprecedented awakening to the potential of biomass conversion elsewhere. This paper considers the rationale and possible benefits of a potential third chapter based on a revitalized effort on biomass conversion …

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Il-23 Produced By Cns-Resident Cells Controls T Cell Encephalitogenicity During The Effector Phase Of Experimental Autoimmune Encephalomyelitis, Burkhard Becher, Brigit G. Durell, Randolph J. Noelle Oct 2003

Il-23 Produced By Cns-Resident Cells Controls T Cell Encephalitogenicity During The Effector Phase Of Experimental Autoimmune Encephalomyelitis, Burkhard Becher, Brigit G. Durell, Randolph J. Noelle

Dartmouth Scholarship

CNS-resident cells, in particular microglia and macrophages, are a source of inflammatory cytokines during inflammation within the CNS. Expression of IL-23, a recently discovered cytokine, has been shown to be critical for the development of experimental autoimmune encephalomyelitis (EAE) in mice. Expression of the p40 subunit of IL-12 and IL-23 by microglia has been shown in situ and in vitro, but direct evidence for a functional significance of p40 expression by CNS cells during an immune response in vivo is still lacking. Here we report that p40 plays a critical role in maintaining encephalitogenicity during the disease course. By using …

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Interpreting Hemoglobin And Water Concentration, Oxygen Saturation, And Scattering Measured In Vivo By Near-Infrared Breast Tomography, Subhadra Srinivasan, Brian W. Pogue, Shudong Jiang, Hamid Dehghani, Christine Kogel, Sandra Soho, Jennifer J. Gibson, Tor D. Tosteson, Steven P. Poplack, Keith D. Paulsen Oct 2003

Interpreting Hemoglobin And Water Concentration, Oxygen Saturation, And Scattering Measured In Vivo By Near-Infrared Breast Tomography, Subhadra Srinivasan, Brian W. Pogue, Shudong Jiang, Hamid Dehghani, Christine Kogel, Sandra Soho, Jennifer J. Gibson, Tor D. Tosteson, Steven P. Poplack, Keith D. Paulsen

Dartmouth Scholarship

Near-infrared spectroscopic tomography was used to measure the properties of 24 mammographically normal breasts to quantify whole-breast absorption and scattering spectra and to evaluate which tissue composition characteristics can be determined from these spectra. The absorption spectrum of breast tissue allows quantification of (i) total hemoglobin concentration, (ii) hemoglobin oxygen saturation, and (iii) water concentration, whereas the scattering spectrum provides information about the size and number density of cellular components and structural matrix elements. These property data were tested for correlation to demographic information, including subject age, body mass index, breast size, and radiographic …

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A Role For Yip1p In Copii Vesicle Biogenesis, Matthew Heidtman, Catherine Z. Chen, Ruth N. Collins, Charles Barlowe Oct 2003

A Role For Yip1p In Copii Vesicle Biogenesis, Matthew Heidtman, Catherine Z. Chen, Ruth N. Collins, Charles Barlowe

Dartmouth Scholarship

Yeast Ypt1p-interacting protein (Yip1p) belongs to a conserved family of transmembrane proteins that interact with Rab GTPases. We encountered Yip1p as a constituent of ER-derived transport vesicles, leading us to hypothesize a direct role for this protein in transport through the early secretory pathway. Using a cell-free assay that recapitulates protein transport from the ER to the Golgi complex, we find that affinity-purified antibodies directed against the hydrophilic amino terminus of Yip1p potently inhibit transport. Surprisingly, inhibition is specific to the COPII-dependent budding stage. In support of this in vitro observation, strains bearing the temperature-sensitive yip1-4 allele accumulate ER membranes …

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Stellar Pollution And [Fe/H] In The Hyades, Aaron Dotter, Brian Chaboyer Oct 2003

Stellar Pollution And [Fe/H] In The Hyades, Aaron Dotter, Brian Chaboyer

Dartmouth Scholarship

The Hyades open cluster presents a unique laboratory for planet formation and stellar pollution studies because all of the stars have essentially the same age and were born from the same cloud of gas. Furthermore, with an age of ~650 Myr, most of the intermediate- and low-mass stars are on the main sequence. Given these assumptions, the accretion of metal-rich material onto the surface of a star during and shortly after the formation of planetary systems should be evident via the enhanced metallicity of the star. Building on previous work, stellar evolution models that include the effects of stellar pollution …

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Mobicom Poster: Evaluating Location Predictors With Extensive Wi-Fi Mobility Data, Libo Song, David Kotz, Ravi Jain, Xiaoning He Oct 2003

Mobicom Poster: Evaluating Location Predictors With Extensive Wi-Fi Mobility Data, Libo Song, David Kotz, Ravi Jain, Xiaoning He

Dartmouth Scholarship

A fundamental problem in mobile computing and wireless networks is the ability to track and predict the location of mobile devices. An accurate location predictor can significantly improve the performance or reliability of wireless network protocols, the wireless network infrastructure itself, and many applications in pervasive computing. These improvements lead to a better user experience, to a more cost-effective infrastructure, or both. Location prediction has been proposed in many areas of wireless cellular networks as a means of enhancing performance, including better mobility management, improved assignment of cells to location areas, more efficient paging, and call admission control. To the …

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Gauge-Invariant Initial Conditions And Early Time Perturbations In Quintessence Universes, Michael Doran, Christian M. Müller, Gregor Schäfer, Christof Wetterich Sep 2003

Gauge-Invariant Initial Conditions And Early Time Perturbations In Quintessence Universes, Michael Doran, Christian M. Müller, Gregor Schäfer, Christof Wetterich

Dartmouth Scholarship

We present a systematic treatment of the initial conditions and evolution of cosmological perturbations in a universe containing photons, baryons, neutrinos, cold dark matter, and a scalar quintessence field. By formulating the evolution in terms of a differential equation involving a matrix acting on a vector comprised of the perturbation variables, we can use the familiar language of eigenvalues and eigenvectors. As the largest eigenvalue of the evolution matrix is fourfold degenerate, it follows that there are four dominant modes with a nondiverging gravitational potential at early times, corresponding to adiabatic, cold dark matter isocurvature, baryon isocurvature and neutrino isocurvature …

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Impact Of Frustrated Singularities On Magnetic Island Evolution, B. D. Jemella, M. A. Shay, J. F. Drake, B. N. Rogers Sep 2003

Impact Of Frustrated Singularities On Magnetic Island Evolution, B. D. Jemella, M. A. Shay, J. F. Drake, B. N. Rogers

Dartmouth Scholarship

The growth of magnetic islands is explored using the magnetohydrodynamic model in a simple slab system in which the value of the tearing mode stability parameter Δ′ can be varied continuously. Unless the system is close to marginal stability reconnection is controlled by Sweet-Parker current layers, whose formation is a consequence of the inherent singular structure of magnetic island equilibria.

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On Friction And Surface Cracking During Sliding Of Ice On Ice, Maurine Montagnat, Erland M. Schulson Sep 2003

On Friction And Surface Cracking During Sliding Of Ice On Ice, Maurine Montagnat, Erland M. Schulson

Dartmouth Scholarship

As a complement to earlier measurements on the friction of both granular fresh-water ice and S2 columnar salt-water ice, new experiments were performed on the friction of S2 columnar fresh-water ice sliding against itself at low velocities (5 × 10−7 to 5 × 10−1 m s−1) and at −10°C, using the same double-shear device as was used earlier. The results showed that under a given set of experimental conditions the kinetic coefficient of friction of S2 fresh-water ice compares favorably with that of the other two variants.The experiments also revealed friction-induced surface cracks and recrystallized grains.These deformation features are explained, …

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Sart Influences Sars Expression In Staphylococcus Aureus, Katherine A. Schmidt, Adhar C. Manna, Ambrose L. Cheung Sep 2003

Sart Influences Sars Expression In Staphylococcus Aureus, Katherine A. Schmidt, Adhar C. Manna, Ambrose L. Cheung

Dartmouth Scholarship

Staphylococcus aureus is a gram-positive pathogen that is capable of expressing a variety of virulence proteins in response to environmental signals. Virulence protein expression in S. aureus is controlled by a network of regulatory loci including sarA and agr. The sarA/agr network is associated with the expression of cell wall-associated adhesins during exponential growth and the expression of secreted enzymes and toxins in the transition to post-exponential growth. A number of sarA homologs, including sarT and sarS, have been identified in the S. aureus genome. Previous studies have shown that sarA influences expression of both sarT and sarS in the …

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A Model Of Zebra Emission In Solar Type Iv Radio Bursts, J. Labelle, R. A. Treumann, P. H. Yoon, M. Karlicky Aug 2003

A Model Of Zebra Emission In Solar Type Iv Radio Bursts, J. Labelle, R. A. Treumann, P. H. Yoon, M. Karlicky

Dartmouth Scholarship

Solar type IV radio bursts present a theoretical challenge because they are composed of both continuum emission and fine structures. The latter include "zebra bursts," which appear as harmonically spaced multiplets that shift in frequency with time. Similarities between these features and terrestrial auroral emissions suggest a new model to explain zebra-structured type IV emissions. In this model, the basic generation mechanism is identical with that proposed by Winglee and Dulk: mode conversion of Z-mode waves generated by the cyclotron maser mechanism under the condition fuh = Nfce, with N an integer; however, we propose a twist …

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Phantom Energy: Dark Energy With W < − 1 Causes A Cosmic Doomsday, Robert R. Caldwell, Marc Kamionkowski, Nevin N. Weinberg Aug 2003

Phantom Energy: Dark Energy With W < − 1 Causes A Cosmic Doomsday, Robert R. Caldwell, Marc Kamionkowski, Nevin N. Weinberg

Dartmouth Scholarship

We explore the consequences that follow if the dark energy is phantom energy, in which the sum of the pressure and energy density is negative. The positive phantom-energy density becomes infinite in finite time, overcoming all other forms of matter, such that the gravitational repulsion rapidly brings our brief epoch of cosmic structure to a close. The phantom energy rips apart the Milky Way, solar system, Earth, and ultimately the molecules, atoms, nuclei, and nucleons of which we are composed, before the death of the Universe in a “big rip.”

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The Virulence Activator Apha Links Quorum Sensing To Pathogenesis And Physiology In Vibrio Cholerae By Repressing The Expression Of A Penicillin Amidase Gene On The Small Chromosome, Gabriela Kovacikova, Wei Lin, Karen Skorupski Aug 2003

The Virulence Activator Apha Links Quorum Sensing To Pathogenesis And Physiology In Vibrio Cholerae By Repressing The Expression Of A Penicillin Amidase Gene On The Small Chromosome, Gabriela Kovacikova, Wei Lin, Karen Skorupski

Dartmouth Scholarship

Activation of the tcpPH promoter on the Vibrio pathogenicity island by AphA and AphB initiates the Vibrio cholerae virulence cascade and is regulated by quorum sensing through the repressive action of HapR on aphA expression. To further understand how the chromosomally encoded AphA protein activates tcpPH expression, site-directed mutagenesis was used to identify the base pairs critical for AphA binding and transcriptional activation. This analysis revealed a region of partial dyad symmetry, TATGCA-N6-TNCNNA, that is important for both of these activities. Searching the V. cholerae genome for this binding site permitted the identification of a second one upstream of a …

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Ccr5 Mediates Specific Migration Of Toxoplasma Gondii—Primed Cd8+ Lymphocytes To Inflammatory Intestinal Epithelial Cells, Souphalone Luangsay, Lloyd H. Kasper, Nicolas Rachinel, Laurie A. Minns Aug 2003

Ccr5 Mediates Specific Migration Of Toxoplasma Gondii—Primed Cd8+ Lymphocytes To Inflammatory Intestinal Epithelial Cells, Souphalone Luangsay, Lloyd H. Kasper, Nicolas Rachinel, Laurie A. Minns

Dartmouth Scholarship

Toxoplasma gondii, an obligate intracellular parasite, can invade intestinal epithelial cells and elicit a robust Th1 immune response. In this model of intestinal inflammation, CD8+ intraepithelial lymphocytes (IELs) secrete transforming growth factor (TGF)-β, which appears necessary for the maintenance of homeostasis in the intestine. However, the mechanism responsible for the IEL migration to the inflamed intestine is still unclear.An in vitro coculture cell system was used to quantify the IEL attraction by an infected intestinal epithelial cell line (m-ICcl2). We used CCR5-deficient mice to determine which chemokine receptor—chemokine interaction could be responsible for the recruitment of …

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Salicylic Acid Attenuates Virulence In Endovascular Infections By Targeting Global Regulatory Pathways In Staphylococcus Aureus, Leon Iri Kupferwasser, Michael R. Yeaman, Cynthia C. Nast, Deborah Kupferwasser, Yan-Qiong Xiong, Marco Palma, Ambrose L. Cheung, Arnold S. Bayer Jul 2003

Salicylic Acid Attenuates Virulence In Endovascular Infections By Targeting Global Regulatory Pathways In Staphylococcus Aureus, Leon Iri Kupferwasser, Michael R. Yeaman, Cynthia C. Nast, Deborah Kupferwasser, Yan-Qiong Xiong, Marco Palma, Ambrose L. Cheung, Arnold S. Bayer

Dartmouth Scholarship

Aspirin has been previously shown to reduce the in vivo virulence of Staphylococcus aureus in experimental endocarditis, through antiplatelet and antimicrobial mechanisms. In the present study, salicylic acid, the major in vivo metabolite of aspirin, mitigated two important virulence phenotypes in both clinical and laboratory S. aureus strains: α-hemolysin secretion and fibronectin binding in vitro. In addition, salicylic acid reduced the expression of the α-hemolysin gene promoter, hla, and the fibronectin gene promoter, fnbA. Transcriptional analysis, fluorometry, and flow cytometry revealed evidence of salicylic acid–mediated activation of the stress-response gene sigB. Expression of the sigB-repressible global …

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Early Quintessence In Light Of Thewilkinson Microwave Anisotropy Probe, Robert R. Caldwell, Michael Doran, Christian M. Mller, Gregor Schfer, Christof Wetterich Jul 2003

Early Quintessence In Light Of Thewilkinson Microwave Anisotropy Probe, Robert R. Caldwell, Michael Doran, Christian M. Mller, Gregor Schfer, Christof Wetterich

Dartmouth Scholarship

We examine the cosmic microwave background (CMB) anisotropy for signatures of early quintessence dark energy—a nonnegligible quintessence energy density during the recombination and structure formation eras. Only very recently does the quintessence overtake the dark matter and push the expansion into overdrive. Because the presence of early quintessence exerts an influence on the clustering of dark matter and the baryon-photon fluid, we may expect to find trace signals in the CMB and the mass fluctuation power spectrum. In detail, we demonstrate that suppressed clustering power on small length scales, as suggested by the combined Wilkinson Microwave Anisotropy Probe/CMB/large-scale structure …

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Use Of In Vivo-Induced Antigen Technology (Iviat) To Identify Genes Uniquely Expressed During Human Infection With Vibrio Cholerae, Long Hang, Manohar John, Muhammad Asaduzzaman, Emily A. Bridges, Cecily Vanderspurt, Thomas J. Kirn, Ronald K. Taylor Jul 2003

Use Of In Vivo-Induced Antigen Technology (Iviat) To Identify Genes Uniquely Expressed During Human Infection With Vibrio Cholerae, Long Hang, Manohar John, Muhammad Asaduzzaman, Emily A. Bridges, Cecily Vanderspurt, Thomas J. Kirn, Ronald K. Taylor

Dartmouth Scholarship

In vivo-induced antigen technology is a method to identify proteins expressed by pathogenic bacteria during human infection. Sera from 10 patients convalescing from cholera infection in Bangladesh were pooled, adsorbed against in vitro-grown El Tor Vibrio cholerae O1, and used to probe a genomic expression library in Escherichia coli constructed from El Tor V. cholerae O1 strain N16961. We identified 38 positive clones in the screen, encoding pili (PilA and TcpA), cell membrane proteins (PilQ, MshO, MshP, and CapK), methyl-accepting chemotaxis proteins, chemotaxis and motility proteins (CheA and CheR), a quorum-sensing protein (LuxP), and four hypothetical proteins. Analysis of immune …

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The Triterpenoid Cddo Inhibits Expression Of Matrix Metalloproteinase-1, Matrix Metalloproteinase-13 And Bcl-3 In Primary Human Chondrocytes, Sarah Elliott, Ezra Hays, Michael Mayor, Michael Sporn, Matthew P. Vincenti Jul 2003

The Triterpenoid Cddo Inhibits Expression Of Matrix Metalloproteinase-1, Matrix Metalloproteinase-13 And Bcl-3 In Primary Human Chondrocytes, Sarah Elliott, Ezra Hays, Michael Mayor, Michael Sporn, Matthew P. Vincenti

Dartmouth Scholarship

A synthetic triterpenoid, 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO), has been reported to have anti-inflammatory properties and to decrease the interleukin-1 (IL-1)-induced expression of matrix metalloproteinase-1 (MMP-1) and MMP-13. We have shown previously that IL-1 induces expression of the inhibitor of NF-κB (IκB) family member Bcl-3, and that this contributes to MMP-1 expression. To quantify the effects of CDDO on IL-1-induced MMP-1, MMP-13 and Bcl-3 expression, we stimulated the chondrosarcoma cell line SW-1353 and human primary chondrocytes with IL-1, in the presence or absence of CDDO. Harvested RNA was subjected to quantitative real-time reverse-transcriptase polymerase chain reaction. In SW-1353 cells, 300 nM CDDO …

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Development Assistance And The Construction Of Government‐Initiated Community Institutions, Eric V. Edmonds Jul 2003

Development Assistance And The Construction Of Government‐Initiated Community Institutions, Eric V. Edmonds

Dartmouth Scholarship

This paper provides new evidence on the role of official development assistance in program implementation. Governments and donors around the world are promoting participatory development and community management program s that transfer responsibilities and rights to local communities. Large-scale implementation of these schemes requires significant funding from multiple sources. I consider a uniform ins titutional reform in Nepal and find that the scope of program implementation and the characteristic s of new institutions vary across types and sources of aid. In my analysis, I develop a geographic matching estimator that compares adjacent communities receiving different types of assistance. This heterogeneity …

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Crystal Structure Of The Sars Protein From Staphylococcus Aureus, Ronggui Li, Adhar C. Manna, Shaodong Dai, Ambrose L. Cheung, Gongyi Zhang Jul 2003

Crystal Structure Of The Sars Protein From Staphylococcus Aureus, Ronggui Li, Adhar C. Manna, Shaodong Dai, Ambrose L. Cheung, Gongyi Zhang

Dartmouth Scholarship

The expression of virulence determinants in Staphylococcus aureus is controlled by global regulatory loci (e.g., sarA and agr). One of these determinants, protein A (spa), is activated by sarS, which encodes a 250-residue DNA-binding protein. Genetic analysis indicated that the agr locus likely mediates spa repression by suppressing the transcription of sarS. Contrary to SarA and SarR, which require homodimer formation for proper function, SarS is unusual within the SarA protein family in that it contains two homologous halves, with each half sharing sequence similarity to SarA and SarR. Here we report the 2.2 Å …

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Alginate Is Not A Significant Component Of The Extracellular Polysaccharide Matrix Of Pa14 And Pao1 Pseudomonas Aeruginosa Biofilms, Daniel J. Wozniak, Timna J. O. Wyckoff, Melissa Starkey, Rebecca Keyser, Parastoo Azadi, George A. O'Toole, Matthew R. Parsek Jun 2003

Alginate Is Not A Significant Component Of The Extracellular Polysaccharide Matrix Of Pa14 And Pao1 Pseudomonas Aeruginosa Biofilms, Daniel J. Wozniak, Timna J. O. Wyckoff, Melissa Starkey, Rebecca Keyser, Parastoo Azadi, George A. O'Toole, Matthew R. Parsek

Dartmouth Scholarship

The bacterium Pseudomonas aeruginosa causes chronic respiratory infections in cystic fibrosis (CF) patients. Such infections are extremely difficult to control because the bacteria exhibit a biofilm-mode of growth, rendering P. aeruginosa resistant to antibiotics and phagocytic cells. During the course of infection, P. aeruginosa usually undergoes a phenotypic switch to a mucoid colony, which is characterized by the overproduction of the exopolysaccharide alginate. Alginate overproduction has been implicated in protecting P. aeruginosa from the harsh environment present in the CF lung, as well as facilitating its persistence as a biofilm by providing an extracellular matrix that promotes adherence. Because of …

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A Functional Relationship Between Numa And Kid Is Involved In Both Spindle Organization And Chromosome Alignment In Vertebrate Cells, Aime A. Levesque, Louisa Howard, Michael B. Gordon, Duane A. Compton Jun 2003

A Functional Relationship Between Numa And Kid Is Involved In Both Spindle Organization And Chromosome Alignment In Vertebrate Cells, Aime A. Levesque, Louisa Howard, Michael B. Gordon, Duane A. Compton

Dartmouth Scholarship

We examined spindle morphology and chromosome alignment in vertebrate cells after simultaneous perturbation of the chromokinesin Kid and either NuMA, CENP-E, or HSET. Spindle morphology and chromosome alignment after simultaneous perturbation of Kid and either HSET or CENP-E were no different from when either HSET or CENP-E was perturbed alone. However, short bipolar spindles with organized poles formed after perturbation of both Kid and NuMA in stark contrast to splayed spindle poles observed after perturbation of NuMA alone. Spindles were disorganized if Kid, NuMA, and HSET were perturbed, indicating that HSET is sufficient for spindle organization in the absence of …

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