The Gelaton Scenario: Equilateral non-Gaussianity from multi-field dynamics

The distinctive features of single field inflationary models with non-minimal kinetic terms, like Dirac-Born-Infeld and k-inflation, can be captured by more familiar multiple field inflationary systems of the type that typically arise in low energy supergravity models. At least one heavy field, which we call the gelaton, has an effective potential which depends on the kinetic energy of the inflaton. Integrating out the gelaton gives rise to an effectively single field system for which the speed of sound for the adiabatic fluctuations is reduced, generating potentially observable equilateral non-Gaussianity, while causing negligible isocurvature fluctuations. This mechanism is only active if there is a relatively tight coupling between the gelaton and the inflaton, and this puts an upper limit on the mass of the gelaton for which the inflaton-gelaton system remains weakly coupled. This approach gives a UV-completable framework for describing large classes of k-inflationary behavior.Comment: v3: 5 pages, very minor changes, matches version published in PR

The Drosophila immunoglobulin gene turtle encodes guidance molecules involved in axon pathfinding

Background: Neuronal growth cones follow specific pathways over long distances in order to reach their appropriate targets. Research over the past 15 years has yielded a large body of information concerning the molecules that regulate this process. Some of these molecules, such as the evolutionarily conserved netrin and slit proteins, are expressed in the embryonic midline, an area of extreme importance for early axon pathfinding decisions. A general model has emerged in which netrin attracts commissural axons towards the midline while slit forces them out. However, a large number of commissural axons successfully cross the midline even in the complete absence of netrin signaling, indicating the presence of a yet unidentified midline attractant. Results: The evolutionarily conserved Ig proteins encoded by the turtle/Dasm1 genes are found in Drosophila, Caenorhabditis elegans, and mammals. In Drosophila the turtle gene encodes five proteins, two of which are diffusible, that are expressed in many areas, including the vicinity of the midline. Using both molecular null alleles and transgenic expression of the different isoforms, we show that the turtle encoded proteins function as non-cell autonomous axonal attractants that promote midline crossing via a netrin-independent mechanism. turtle mutants also have either stalled or missing axon projections, while overexpression of the different turtle isoforms produces invasive neurons and branching axons that do not respect the histological divisions of the nervous system. Conclusion: Our findings indicate that the turtle proteins function as axon guidance cues that promote midline attraction, axon branching, and axonal invasiveness. The latter two capabilities are required by migrating axons to explore densely packed targets

A non-equilibrium dynamic mechanism for the allosteric effect

Allosteric regulation is often viewed as thermodynamic in nature. However protein internal motions during an enzymatic reaction cycle can be slow hopping processes over numerous potential barriers. We propose that regulating molecules may function by modifying the nonequilibrium protein dynamics. The theory predicts that an enzyme under the new mechanism has different temperature dependence, waiting time distribution of the turnover cycle, and dynamic fluctuation patterns with and without effector. Experimental tests of the theory are proposed.Comment: accepted by Phys. Rev. Lett. Major revisions were made to fit the style. 4 pages, 2 figure

Egg Production in the Boxelder Bug \u3ci\u3eBoisea Trivittata\u3c/i\u3e (Hemiptera: Rhopalidae)

Boxelder bug females emerged from overwintering sites in the spring and rapidly provisioned eggs with yolk materials. Five discrete egg stages were identified based on egg size, protein content, and degree of chorion sclerotization. Females did not accumulate yolk materials into the egg until after melanization was completed, as unmelanized animals rarely possessed even stage 2 eggs. All adult females entering overwintering sites possessed only immature stage eggs (stage 1 and 2). The rate of egg vitellogenesis in the spring was rapid; a major change in numbers of more mature stage eggs (stage 3 and above) in the ovary occurred within approximately 6 days. Most mating pairs recovered in the field (92%, 12/13) possessed ovaries full of eggs in stages 3, 4 or 5. The remaining female contained only immature eggs of stage 1 and 2. This finding indicates that fully provisioned ovaries are not an absolute requirement for mating to occur. The signals that initiate vitellogenesis and control the movement of materials from fat body into eggs are unknown for the boxelder bug

Interpreting the dependence of mutation rates on age and time

Mutations can arise from the chance misincorporation of nucleotides during DNA replication or from DNA lesions that are not repaired correctly. We introduce a model that relates the source of mutations to their accumulation with cell divisions, providing a framework for understanding how mutation rates depend on sex, age and absolute time. We show that the accrual of mutations should track cell divisions not only when mutations are replicative in origin but also when they are non-replicative and repaired efficiently. One implication is that the higher incidence of cancer in rapidly renewing tissues, an observation ascribed to replication errors, could instead reflect exogenous or endogenous mutagens. We further find that only mutations that arise from inefficiently repaired lesions will accrue according to absolute time; thus, in the absence of selection on mutation rates, the phylogenetic "molecular clock" should not be expected to run steadily across species.Comment: 5 figures, 2 table

The SERI solar energy storage program

In support of the DOE thermal and chemical energy storage program, the solar energy storage program (SERI) provides research on advanced technologies, systems analyses, and assessments of thermal energy storage for solar applications in support of the Thermal and Chemical Energy Storage Program of the DOE Division of Energy Storage Systems. Currently, research is in progress on direct contact latent heat storage and thermochemical energy storage and transport. Systems analyses are being performed of thermal energy storage for solar thermal applications, and surveys and assessments are being prepared of thermal energy storage in solar applications. A ranking methodology for comparing thermal storage systems (performance and cost) is presented. Research in latent heat storage and thermochemical storage and transport is reported

The Devil We Already Know: Medieval Representations of a Powerless Satan in Modern American Cinema

The character of Satan has been explored repeatedly in American films, although neither film nor religion scholars have extensively investigated the topic. This article examines the medieval Christian roots of Satan as seen in American cinema and proposes that the most identifiable difference between the medieval Devil and the Satan shown in American films is his level of power over humanity. Hollywood\u27s Satans echo medieval depictions of Satan in form, appearance, and ways of interacting with humans. Although less frightening, pop culture\u27s view of Satan - even when he is treated humorously - is thus linked through movies to medieval religious beliefs

Sound From The Pines : Morceau Descriptive

https://digitalcommons.library.umaine.edu/mmb-ps/1070/thumbnail.jp