Faculty Scholarship
Showing 261 - 270 of 733 Items
Haplotype mapping of a diploid non-meiotic organism using existing and induced aneuploidies
Date: 2008-01-01
Creator: Melanie Legrand, Anja Forche, Anna Selmecki, Christine Chan, David T., Kirkpatrick, Judith Berman
Access: Open access
- Haplotype maps (HapMaps) reveal underlying sequence variation and facilitate the study of recombination and genetic diversity. In general, HapMaps are produced by analysis of Single-Nucleotide Polymorphism (SNP) segregation in large numbers of meiotic progeny. Candida albicans, the most common human fungal pathogen, is an obligate diploid that does not appear to undergo meiosis. Thus, standard methods for haplotype mapping cannot be used. We exploited naturally occurring aneuploid strains to determine the haplotypes of the eight chromosome pairs in the C. albicans laboratory strain SC5314 and in a clinical isolate. Comparison of the maps revealed that the clinical strain had undergone a significant amount of genome rearrangement, consisting primarily of crossover or gene conversion recombination events. SNP map haplotyping revealed that insertion and activation of the UAU1 cassette in essential and non-essential genes can result in whole chromosome aneuploidy. UAU1 is often used to construct homozygous deletions of targeted genes in C. albicans; the exact mechanism (trisomy followed by chromosome loss versus gene conversion) has not been determined. UAU1 insertion into the essential ORC1 gene resulted in a large proportion of trisomic strains, while gene conversion events predominated when UAU1 was inserted into the non-essential LRO1 gene. Therefore, induced aneuploidies can be used to generate HapMaps, which are essential for analyzing genome alterations and mitotic recombination events in this clonal organism. © 2008 Legrand et al.
Spending Fast and Furious: Political Advertising in 2020
Date: 2021-03-01
Creator: Travis N. Ridout, Erika Franklin Fowler, Michael M. Franz
Access: Open access
- This article is a "first look"at political advertising in 2020. Spending on political advertising in the United States in 2020 obliterated records, and Democrats held huge advantages in the presidential race and in most congressional and senatorial races. In addition, all indicators suggest that spending on digital advertising continued to rise. Political advertising was largely similar in tone to past years and, in the presidential race, was substantially more positive than 2016. In addition, interest groups remained heavily involved in federal races in 2020, airing more ads than ever before, though their spending as a percentage of total ad spending was slightly less than in 2016. Political ad spending in 2020 may have been historically high because of the impact of COVID-19 on how campaigns could reach voters, suggesting that paid advertising may decline in 2022 and 2024, at least as a percentage of total election spending.
Carbon and hydrogen isotopic composition of methane over the last 1000 years
Date: 2009-10-01
Creator: J. A. Mischler, T. A. Sowers, R. B. Alley, M. Battle, J. R., McConnell, L. Mitchell, T. Popp, E. Sofen, M. K. Spencer
Access: Open access
- New measurements of the carbon and hydrogen isotopic ratios of methane (δ13 C of CH4 and δD of CH4) over the last millennium are presented from the WAIS Divide, Antarctica, ice core (WDC05A), showing significant changes that likely were the result of human influences prior to the industrial revolution (at least as early as the 16th century of the common era (CE)). The (δ13C of CH4 data corroborate the record from Law Dome, Antarctica, with high fidelity. The new δD of CH4 data set covaries with the (δ13C of CH4 record. Both (δ13C of CH4 and δD of CH4 were relatively stable and close to the present-day values from ∼to ∼CE. Both isotopic ratios decreased to minima around 1700 CE, remained low until the late 18th century, and then rose exponentially to present-day values. Our new δD of CH4 data provide an additional independent constraint for evaluating possible CH4 source histories. We searched a broad range of source scenarios using a simple box model to identify histories consistent with the constraints of the CH 4 concentration and isotope data from 990-1730 CE. Results typically show a decrease over time in the biomass-burning source (found in 85% of acceptable scenarios) and an increase in the agricultural source (found in 77% of acceptable scenarios), indicating preindustrial human influence on atmospheric methane as proposed in previous studies. © 2009 by the American Geophysical Union.
Higgs-regularized three-loop four-gluon amplitude in N = 4 SYM: Exponentiation and Regge limits
Date: 2010-01-01
Creator: Johannes M. Henn, Stephen G. Naculich, Howard J. Schnitzer, Marcus Spradlin
Access: Open access
- We compute the three-loop contribution to the N = 4 supersymmetric Yang- Mills planar four-gluon amplitude using the recently-proposed Higgs IR regulator of Alday, Henn, Plefka, and Schuster. In particular, we test the proposed exponential ansatz for the four-gluon amplitude that is the analog of the BDS ansatz in dimensional regularization. By evaluating our results at a number of kinematic points, and also in several kinematic limits, we establish the validity of this ansatz at the three-loop level. We also examine the Regge limit of the planar four-gluon amplitude using several different IR regulators: dimensional regularization, Higgs regularization, and a cutoff regularization. In the latter two schemes, it is shown that the leading logarithmic (LL) behavior of the amplitudes, and therefore the lowest-order approximation to the gluon Regge trajectory, can be correctly obtained from the ladder approximation of the sum of diagrams. In dimensional regularization, on the other hand, there is no single dominant set of diagrams in the LL approximation. We also compute the NLL and NNLL behavior of the L-loop ladder diagram using Higgs regularization. © SISSA 2010.
Do Infant Temperament Characteristics Predict Core Academic Abilities in Preschool-Aged Children?
Date: 2016-01-01
Creator: Maria A. Gartstein, Samuel P. Putnam, Rachel Kliewer
Access: Open access
- Examined relationships between temperament, measured via parent report at 4 months and structured laboratory observations at 12 months of age, and a school readiness battery administered at about 4 years of age (N =31). Scores on the School Readiness Assessment of the Bracken Basic Concept Scale (BBCS) were related to infant Positive Affectivity/Surgency (PAS), with infants described as demonstrating higher levels of PAS at 4 months of age later demonstrating greater school readiness in the domains of color, letter, and number skills. Regulatory Capacity/Orienting (RCO) at 4 months also predicted color skills, with more regulated infants demonstrating superior pre-academic functioning in this area. Analyses involving laboratory observations of temperament provided additional information concerning the importance of infant Positive Affectivity/Surgency, predictive of letter skills and overall school-readiness scores later in childhood. Results are discussed in the context of implications for theory and research, as well as early education settings.
Level-rank duality of untwisted and twisted D-branes
Date: 2006-05-15
Creator: Stephen G. Naculich, Howard J. Schnitzer
Access: Open access
- Level-rank duality of untwisted and twisted D-branes of WZW models is explored. We derive the relation between D0-brane charges of level-rank dual untwisted D-branes of over(su, ̂) ( N )K and over(sp, ̂) ( n )k, and of level-rank dual twisted D-branes of over(su, ̂) ( 2 n + 1 )2 k + 1. The analysis of level-rank duality of twisted D-branes of over(su, ̂) ( 2 n + 1 )2 k + 1 is facilitated by their close relation to untwisted D-branes of over(sp, ̂) ( n )k. We also demonstrate level-rank duality of the spectrum of an open string stretched between untwisted or twisted D-branes in each of these cases. © 2006 Elsevier B.V. All rights reserved.
Event-related potential correlates of interference effects on recognition memory
Date: 2008-02-01
Creator: Kenneth A. Norman, Katharine Tepe, Erika Nyhus, Tim Curran
Access: Open access
- The question of interference (how new learning affects previously acquired knowledge and vice versa) is a central theoretical issue in episodic memory research, but very few human neuroimaging studies have addressed this question. Here, we used event-related potentials (ERPs) to test the predictions of the complementary learning systems (CLS) model regarding how list strength manipulations (strengthening some, but not all, items on a study list) affect recognition memory. Our analysis focused on the FN400 old-new effect, a hypothesized ERP correlate of familiarity-based recognition, and the parietal old-new effect, a hypothesized ERP correlate of recollection-based recognition. As is predicted by the CLS model, increasing list strength selectively reduced the ERP correlate of recollection-based discrimination, leaving the ERP correlate of familiarity-based discrimination intact. In a second experiment, we obtained converging evidence for the CLS model's predictions, using a remember/know test: Increasing list strength reduced recollection-based discrimination but did not reduce familiarity-based discrimination. Copyright 2008 Psychonomic Society, Inc.
Components of the Springer fiber and domino tableaux
Date: 2004-02-15
Creator: Thomas Pietraho
Access: Open access
- Consider a complex classical semisimple Lie group along with the set of its nilpotent coadjoint orbits. When the group is of type A, the set of orbital varieties contained in a given nilpotent orbit is described a set of standard Young tableaux. We parameterize both, the orbital varieties and the irreducible components of unipotent varieties in the other classical groups by sets of standard domino tableaux. The main tools are Spaltenstein's results on signed domino tableaux together with Garfinkle's operations on standard domino tableaux. © 2004 Elsevier Inc. All rights reserved.
Level-rank duality of the U(N) WZW model, Chern-Simons theory, and 2d qYM theory
Date: 2007-06-01
Creator: Stephen G. Naculich, Howard J. Schnitzer
Access: Open access
- We study the WZW, Chern-Simons, and 2d qYM theories with gauge group U(N). The U(N) WZW model is only well-defined for odd level K, and this model is shown to exhibit level-rank duality in a much simpler form than that for SU(N). The U(N) Chern-Simons theory on Seifert manifolds exhibits a similar duality, distinct from the level-rank duality of SU(N) Chern-Simons theory on S 3. When q ≤ e2πi/(N+K), the observables of the 2d U(N) qYM theory can be expressed as a sum over a finite subset of U(N) representations. When N and K are odd, the qYM theory exhibits N K duality, provided q ≤ e2πi/(N+K) and θ ≤ 0 mod 2π/(N + K). © SISSA 2007.
A 60 yr record of atmospheric carbon monoxide reconstructed from Greenland firn air
Date: 2013-08-19
Creator: V. V. Petrenko, P. Martinerie, P. Novelli, D. M. Etheridge, I., Levin, Z. Wang, T. Blunier, J. Chappellaz, J. Kaiser, P. Lang, L. P. Steele, S. Hammer, J. Mak, R. L. Langenfelds, J. Schwander, J. P. Severinghaus, E. Witrant, G. Petron, M. O. Battle, G. Forster, W. T. Sturges, J. F. Lamarque, K. Steffen, J. W.C. White
Access: Open access
- We present the first reconstruction of the Northern Hemisphere (NH) high latitude atmospheric carbon monoxide (CO) mole fraction from Greenland firn air. Firn air samples were collected at three deep ice core sites in Greenland (NGRIP in 2001, Summit in 2006 and NEEM in 2008). CO records from the three sites agree well with each other as well as with recent atmospheric measurements, indicating that CO is well preserved in the firn at these sites. CO atmospheric history was reconstructed back to the year 1950 from the measurements using a combination of two forward models of gas transport in firn and an inverse model. The reconstructed history suggests that Arctic CO in 1950 was 140-150 nmol mol-1, which is higher than today's values. CO mole fractions rose by 10-15 nmol mol-1 from 1950 to the 1970s and peaked in the 1970s or early 1980s, followed by a ≈ 30 nmol mol-1 decline to today's levels. We compare the CO history with the atmospheric histories of methane, light hydrocarbons, molecular hydrogen, CO stable isotopes and hydroxyl radicals (OH), as well as with published CO emission inventories and results of a historical run from a chemistry-transport model. We find that the reconstructed Greenland CO history cannot be reconciled with available emission inventories unless unrealistically large changes in OH are assumed. We argue that the available CO emission inventories strongly underestimate historical NH emissions, and fail to capture the emission decline starting in the late 1970s, which was most likely due to reduced emissions from road transportation in North America and Europe. © Author(s) 2013.