Studies of the Lysogenic Response as a Function of Multiplicity of Infection of Lambdoid Bacteriophages

The lambdoid bacteriophages λimmλ, λimm434 and λcI are ideal subjects for the study of gene product interactions at the molecular level due to their closely related genetic makeup. Previous work in this laboratory has indicated the possibility that phage λimm is sensitive to phage λimm434cI gene product and that phage λimm434 is sensitive to phage λimmλcI gene product. The purpose of this research was to determine if the frequency of lysogeny for phage λimmλ is affected by the multiplicity of coinfection with the λimm434 phage. By comparing the graph of the frequency of lysogeny versus multiplicity of infection for λimmλ alone with the graph of the frequency of lysogeny versus multiplicity of infection for λimmλ coinfected with λimm434 it is possible to determine whether the lysogenic response of λimmλ utilizes the cI gene product of phage λimm434. The results of this study demonstrate clearly that λimm434 has no multiplicity of infection - dependent effect upon the ability of λimmλ to enter the lysogenic state. The combined results of the present study and previous work in this laboratory suggest that although the cI gene of one phage does appear to influence the reproduction of the other, the effect does not involve the primary function of cI, that is, initiation of lysogeny. This suggests that the cI gene could possibly have other functions besides producing repressor protein

Studies of the Lysogenic Response as a Function of Multiplicity of Infection of Lambdoid Bacteriophages

The lambdoid bacteriophages λimmλ, λimm434 and λcI are ideal subjects for the study of gene product interactions at the molecular level due to their closely related genetic makeup. Previous work in this laboratory has indicated the possibility that phage λimm is sensitive to phage λimm434cI gene product and that phage λimm434 is sensitive to phage λimmλcI gene product. The purpose of this research was to determine if the frequency of lysogeny for phage λimmλ is affected by the multiplicity of coinfection with the λimm434 phage. By comparing the graph of the frequency of lysogeny versus multiplicity of infection for λimmλ alone with the graph of the frequency of lysogeny versus multiplicity of infection for λimmλ coinfected with λimm434 it is possible to determine whether the lysogenic response of λimmλ utilizes the cI gene product of phage λimm434. The results of this study demonstrate clearly that λimm434 has no multiplicity of infection - dependent effect upon the ability of λimmλ to enter the lysogenic state. The combined results of the present study and previous work in this laboratory suggest that although the cI gene of one phage does appear to influence the reproduction of the other, the effect does not involve the primary function of cI, that is, initiation of lysogeny. This suggests that the cI gene could possibly have other functions besides producing repressor protein

Micromagnetic characteristics of transverse diffuse domain boundaries in permalloy thin films

Transverse domain boundaries propagating in the longitudinal direction at speeds one to three orders of magnitude faster than normal domain walls are responsible for most of the lower speed reversals in magnetic thin films. Using a 10-ns exposure time Kerr magnetooptic camera, these boundaries have been photographed for a variety of applied fields in several films with thicknesses ranging from 500 to 3500 Å. High-magnification photographs of the boundary transition region reveal that the boundaries consist of small isolated areas of reversed and partially reversed magnetization in a nonreversed background. Propagation occurs by the nucleation of additional small areas of reverse magnetization within and ahead of the transition region. In a given film the width of the transition region increases as the applied field is increased. By approximating the divergence of the magnetization at the boundary as a line charge, a model has been derived which predicts the boundary widthWto beW = \frac{8M_{s}t}{H_{n}}\frac{1}{(1-H/H_{n})}where Msis the saturation magnetization andHis the applied field. The nucleation threshold Hnis the threshold at which nucleation is observed over all the film. The experimental data fit this predicted dependence quite well. The rapid increase in width of the transition region with applied field is correlated with a rapid nonlinear increase in the velocity of propagation

Aggression and Coexistence in Female Caribou

Female caribou (Rangifer tarandus) are highly gregarious, yet there has been little study of the behavioral mechanisms that foster coexistence. Quantifying patterns of aggression between male and female, particularly in the only cervid taxa where both sexes grow antlers, should provide insight into these mechanisms. We asked if patterns of aggression by male and female caribou followed the pattern typically noted in other polygynous cervids, in which males display higher frequencies and intensity of aggression. From June to August in 2011 and 2012, we measured the frequency and intensity of aggression across a range of group sizes through focal animal sampling of 170 caribou (64 males and 106 females) on Adak Island in the Aleutian Archipelago, Alaska. Males in same-sex and mixed-sex groups and females in mixed-sex groups had higher frequencies of aggression than females in same-sex groups. Group size did not influence frequency of aggression. Males displayed more intense aggression than females. Frequent aggression in mixed-sex groups probably reflects lower tolerance of males for animals in close proximity. Female caribou were less aggressive and more gregarious than males, as in other polygynous cervid species.La femelle caribou (Rangifer tarandus) est très grégaire et pourtant, très peu d’études ont été faites sur les mécanismes du comportement qui favorisent la coexistence. Des modèles quantificateurs d’agression entre le mâle et la femelle, particulièrement chez le seul cervidé où les deux sexes possèdent des bois, devraient permettre d’en savoir plus sur ces mécanismes. Nous nous sommes demandé si les modèles d’agression entre la femelle et le mâle caribou ressemblaient aux modèles d’agression généralement remarqués chez d’autres cervidés polygynes, pour lesquels les mâles affichent une fréquence et une intensité d’agression plus grandes. De juin à août 2011 et 2012, nous avons mesuré la fréquence et l’intensité d’agression au sein de groupes de tailles diverses, et ce, au moyen de l’échantillonnage centré de 170 caribous (64 mâles et 106 femelles) sur l’île Adak de l’archipel des Aléoutiennes, en Alaska. Les mâles des groupes du même sexe et des groupes mixtes, et les femelles de groupes mixtes affichaient une plus grande fréquence d’agression que les femelles se trouvant dans des groupes du même sexe. La fréquence d’agression n’était aucunement influencée par la taille du groupe. L’intensité d’agression des mâles était plus grande chez le mâle que chez la femelle. L’agression fréquente dans les groupes mixtes est probablement représentative de la plus faible tolérance des mâles à la présence d’animaux à proximité. Les femelles caribou étaient moins agressives et plus grégaires que les mâles, à l’instar d’autres espèces de cervidés polygynes

Equation-Based Congestion Control for Unicast Applications: the Extended Version

This paper proposes a mechanism for equation-based congestion control for unicast traffic. Most best-effort traffic in the current Internet is well-served by the dominant transport protocol TCP. However, traffic such as best-effort unicast streaming multimedia could find use for a TCP-friendly congestion control mechanism that refrains from reducing the sending rate in half in response to a single packet drop. With our mechanism, the sender explicitly adjusts its sending rate as a function of the measured rate of loss events, where a loss event consists of one or more packets dropped within a single round-trip time. We use both simulations and experiments over the Internet to explore performance. Equation-based congestion control is also a promising avenue of development for congestion control of multicast traffic, and so an additional reason for this work is to lay a sound basis for the later development of multicast congestion control

Labor and Employment: The Battle for the Gig Economy

The following is a transcript of a 2016 Federalist Society panel entitled Labor & Employment Law: The Battle for the Gig Economy. The panel originally occurred on November 17, 2016 during the National Lawyers Convention in Washington, D.C. The panelists were: Mark Brnovich, Attorney General, Arizona; Mr. Mark Floyd, Senior Director and Global Relations Lead, Uber Technologies Inc.; Mr. Randel K. Johnson, Senior Vice President, Labor, Immigration and Employee Benefits, U.S. Chamber of Commerce; and Mr. Bill Samuel, Director of Government Affairs, AFL-CIO. The moderator was the Honorable Judge Thomas M. Hardiman of the U.S. Court of Appeals, Third Circuit

Colorado Natural Heritage Program 1995 (with material added in 1997)

From cover: "Colorado Natural Heritage Program 1995 (with material added in 1997)."15 January 1996.Prepared for: U.S. Forest Service, Leadville Ranger District; by Susan Spackman, Mark Duff, Sandra Floyd