Constructing computer virus phylogenies

There has been much recent algorithmic work on the problem of reconstructing the evolutionary history of biological species. Computer virus specialists are interested in finding the evolutionary history of computer viruses - a virus is often written using code fragments from one or more other viruses, which are its immediate ancestors. A phylogeny for a collection of computer viruses is a directed acyclic graph whose nodes are the viruses and whose edges map ancestors to descendants and satisfy the property that each code fragment is "invented" only once. To provide a simple explanation for the data, we consider the problem of constructing such a phylogeny with a minimum number of edges. In general this optimization problem is NP-complete; some associated approximation problems are also hard, but others are easy. When tree solutions exist, they can be constructed and randomly sampled in polynomial time

Coupling Manure Injection with Cover Crops to Enhance Nutrient Cycling

Large-scale hog (Sus scroja) production is a major agricultural enterprise in the Midwest. Large numbers of confined hogs produce about 50 million tons per year of swine manure in Iowa alone. Rapid expansion of concentrated animal feeding operations (CAFOs) has resulted in increased concentrations of manure nutrients in surface waters which contribute about 15% of the total nitrate load in the Mississippi River Basin. Producers are being encouraged to develop manure management practices that fulfill crop production requirements, while minimizing the potential for environmental pollution. The most commonly used manure management practice in the Midwest involves fall application to land where corn (Zea mays L.) will be grown in the subsequent growing season. Fall planted annual cover crops can capture manure nutrients and immobilize them in plant biomass, subsequently reducing the potential for nutrient loss through run-off or leaching. Decomposition of cover crop residue the following spring may help synchronize manure N availability and corn N uptake, improving nutrient-use efficiency within the crop rotation

Social Category Diversity Promotes Premeeting Elaboration: The Role of Relationship Focus

A purported downside of social category diversity is decreased relationship focus (i.e., one’s focus on establishing a positive social bond with a coworker). However, we argue that this lack of relationship focus serves as a central mechanism that improves information processing even prior to interaction and, ultimately, decision-making performance in diverse settings. We introduce the construct of premeeting elaboration (i.e., the extent to which individuals consider their own and others’ perspectives in the anticipation of an interaction) and explore its link with social category diversity and relationship focus. Experiments 1 and 2 demonstrate that when disagreement occurs, social category diversity increases premeeting elaboration, with relationship focus as a central causal mechanism. Experiment 3 shows that premeeting elaboration has important implications for performance: disagreeing dyads with social category diversity elaborate more prior to meeting and, as a result, perform better on a decision-making task than those with social category homogeneity. We discuss the value of studying early-stage interaction and propose a reconsideration of the “downside” of social category diversity.Kellogg School of Managemen

The Post-Common Envelope and Pre-Cataclysmic Binary PG 1224+309

We have made extensive spectroscopic and photometric observations of PG 1224+309, a close binary containing a DA white dwarf primary and an M4+ secondary. The H alpha line is in emission due to irradiation of the M-star by the hot white dwarf and is seen to vary around the orbit. From the radial velocities of the H alpha line we derive a period of P = 0.258689 +/- 0.000004 days and a semi-amplitude of K_Halpha = 160 +/- 8 km/s. We estimate a correction Delta_K = 21 +/- 2 km/s, where K_M = K_Halpha + Delta_K. Radial velocity variations of the white dwarf reveal a semi-amplitude of K_WD = 112 +/- 14 km/s. The blue spectrum of the white dwarf is well fit by a synthetic spectrum having T_eff = 29,300 K and log(g) = 7.38. The white dwarf contributes 97% of the light at 4500 Angstroms and virtually all of the light blueward of 3800 Angstroms. No eclipses are observed. The mass inferred for the white dwarf depends on the assumed mass of the thin residual hydrogen envelope: 0.40 < M_WD < 0.45 solar masses for hydrogen envelope masses of 0 < M_H < 4.0E-4 solar masses. We argue that the mass of the white dwarf is closer to 0.45 solar masses, hence it appears that the white dwarf has a relatively large residual hydrogen envelope. The mass of the M-star is then M_M = 0.28 +/- 0.05 solar masses, and the inclination is i = 77 +/- 7 degrees. We discuss briefly how PG 1224+309 may be used to constrain theories of close binary star evolution, and the past and future histories of PG 1224+309 itself. The star is both a ``post-common envelope'' star and a ``pre-cataclysmic binary'' star. Mass transfer by Roche-lobe overflow should commence in about 10 Gyr.Comment: 17 pages, 8 figures, AAS LaTeX, to appear in AJ, March 199

Inhibition of neutrophil apoptosis by PAI-1

Increased circulating and tissue levels of plasminogen activator inhibitor 1 (PAI-1) are often present in severe inflammatory states associated with neutrophil activation and accumulation and correlate with poor clinical outcome from many of these conditions. The mechanisms by which PAI-1 contributes to inflammation have not been fully delineated. In the present experiments, we found that addition of PAI-1 to neutrophil cultures diminished the rate of spontaneous and TNFrelated apoptosis-inducing ligand-induced apoptotic cell death. The effects of PAI-1 on cell viability were associated with activation of antiapoptotic signaling pathways, including upregulation of PKB/Akt, Mcl-1, and Bcl-xL. Although urokinase-plasminogen activator receptor, lipoprotein receptor-related protein, and vitronectin are primary ligands for PAI-1, these molecules were not involved in mediating its antiapoptotic properties. In contrast, blocking pertussis toxin-sensitive G protein-coupled receptors and selective inhibition of phosphatidylinositide 3-kinase reversed the ability of PAI-1 to extend neutrophil viability. The antiapoptotic effects of PAI-1 were also evident under in vivo conditions during LPS-induced acute lung injury, where enhanced apoptosis was present among neutrophils accumulating in the lungs of PAI-1-/- compared with PAI-1+/+ mice. These results demonstrate a novel antiapoptotic role for PAI-1 that may contribute to its participation in neutrophil-associated inflammatory responses. © 2011 the American Physiological Society

Expanding Dress Code Requirements in the Doctor of Pharmacy Program

Although the use of a professional dress code is standard practice across colleges and schools of pharmacy during introductory and advanced pharmacy practice experiences, requiring professional attire is not applied consistently during the didactic portion of students’ education. There are arguments for and against the adoption of a professional dress code throughout the entire doctor of pharmacy program, including the classroom setting. Given uncertainty regarding the potential benefits and challenges that may arise from adopting a professional dress code in the didactic portion of a student pharmacist’s education, it is perhaps not surprising that programs adopt disparate policies regarding its use. This exploration was conducted as part of a series of debates held in conjunction with the American Association of Colleges of Pharmacy’s (AACP) Academic Leadership Fellows Program (ALFP) and was presented at the 2015 AACP Interim Meeting on February 7, 2015

Stages of the Demographic Transition from a Child's Perspective: Family Size, Cohort Size, and Children's Resources

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71989/1/j.1728-4457.2008.00218.x.pd

Observations of the SW Sextantis star DW Ursae Majoris with the Far Ultraviolet Spectroscopic Explorer

We present an analysis of the first far-ultraviolet observations of the SW Sextantis-type cataclysmic variable DW Ursae Majoris, obtained in November 2001 with the Far Ultraviolet Spectroscopic Explorer. The time-averaged spectrum of DW UMa shows a rich assortment of emission lines (plus some contamination from interstellar absorption lines including molecular hydrogen). Accretion disk model spectra do not provide an adequate fit to the far-ultraviolet spectrum of DW UMa. We constructed a light curve by summing far-ultraviolet spectra extracted in 60-sec bins; this shows a modulation on the orbital period, with a maximum near photometric phase 0.93 and a minimum half an orbit later. No other periodic variability was found in the light curve data. We also extracted spectra in bins spanning 0.1 in orbital phase; these show substantial variation in the profile shapes and velocity shifts of the emission lines during an orbital cycle of DW UMa. Finally, we discuss possible physical models that can qualitatively account for the observed far-ultraviolet behavior of DW UMa, in the context of recent observational evidence for the presence of a self-occulting disk in DW UMa and the possibility that the SW Sex stars may be the intermediate polars with the highest mass transfer rates and/or weakest magnetic fields.Comment: accepted by the Astronomical Journal; 36 pages, including 12 figures and 4 table