5,914 research outputs found

    A review of the biology of Octopus vulgaris and its use as a laboratory animal

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    The high degree of neurophysiology and behavioural complexity of Octopus vulgaris had led to its inclusion in the Animals (Scientific Procedures) Act 1986. This paper reviews the biology of O. vulgaris and consider its usage as a laboratory animal

    Refinement in Laboratory Animal Science: Is it a Cinderella subject, and is there conflict and imbalance within the 3 Rs?

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    The role of water-vapour photodissociation on the formation of a deep minimum in mesopause ozone

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    Laboratory Experiments, Numerical Simulations, and Astronomical Observations of Deflected Supersonic Jets: Application to HH 110

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    Collimated supersonic flows in laboratory experiments behave in a similar manner to astrophysical jets provided that radiation, viscosity, and thermal conductivity are unimportant in the laboratory jets, and that the experimental and astrophysical jets share similar dimensionless parameters such as the Mach number and the ratio of the density between the jet and the ambient medium. Laboratory jets can be studied for a variety of initial conditions, arbitrary viewing angles, and different times, attributes especially helpful for interpreting astronomical images where the viewing angle and initial conditions are fixed and the time domain is limited. Experiments are also a powerful way to test numerical fluid codes in a parameter range where the codes must perform well. In this paper we combine images from a series of laboratory experiments of deflected supersonic jets with numerical simulations and new spectral observations of an astrophysical example, the young stellar jet HH 110. The experiments provide key insights into how deflected jets evolve in 3-D, particularly within working surfaces where multiple subsonic shells and filaments form, and along the interface where shocked jet material penetrates into and destroys the obstacle along its path. The experiments also underscore the importance of the viewing angle in determining what an observer will see. The simulations match the experiments so well that we can use the simulated velocity maps to compare the dynamics in the experiment with those implied by the astronomical spectra. The experiments support a model where the observed shock structures in HH 110 form as a result of a pulsed driving source rather than from weak shocks that may arise in the supersonic shear layer between the Mach disk and bow shock of the jet's working surface.Comment: Full resolution figures available at http://sparky.rice.edu/~hartigan/pub.html To appear in Ap

    Parity-Violating Interaction Effects in the np System

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    We investigate parity-violating observables in the np system, including the longitudinal asymmetry and neutron-spin rotation in np elastic scattering, the photon asymmetry in np radiative capture, and the asymmetries in deuteron photo-disintegration d(gamma,n)p in the threshold region and electro-disintegration d(e,e`)np in quasi-elastic kinematics. To have an estimate of the model dependence for the various predictions, a number of different, latest-generation strong-interaction potentials--Argonne v18, Bonn 2000, and Nijmegen I--are used in combination with a weak-interaction potential consisting of pi-, rho-, and omega-meson exchanges--the model known as DDH. The complete bound and scattering problems in the presence of parity-conserving, including electromagnetic, and parity-violating potentials is solved in both configuration and momentum space. The issue of electromagnetic current conservation is examined carefully. We find large cancellations between the asymmetries induced by the parity-violating interactions and those arising from the associated pion-exchange currents. In the np capture, the model dependence is nevertheless quite small, because of constraints arising through the Siegert evaluation of the relevant E1 matrix elements. In quasi-elastic electron scattering these processes are found to be insignificant compared to the asymmetry produced by gamma-Z interference on individual nucleons.Comment: 65 pages, 26 figures, submitted to PR

    Nonprofit governance: Improving performance in troubled economic times

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    Nonprofit management is currently pressured to perform effectively in a weak economy. Yet, nonprofit governance continues to suffer from unclear conceptions of the division of labor between board of directors and executive directors. This online survey of 114 executive directors aims to provide clarification and recommendations for social administration

    Exploring Expressions of Possible Selves with High School and College Students with Learning Disabilities

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    In this article, we explore a program designed to engage high school and college students with learning disabilities (LD) in conversations about their hopes, expectations, and fears for the future. We explore the mindset of students by focusing on their self-identified passions for life and sense of strengths and limitations. We found that males and females differed in goals related to Academics, Work Ethic, Degree Specific Statements, and Money and Finances. For example, females emphasized “Academic Goals” more frequently than males and focused on topics such as GPA and work ethic in school. However, males made more “Degree Specific Statements” than females, more often emphasizing the desire to be financially stable or have a career with a large income. These differences suggest that college transition staff may want to focus on goals identified by male and female students with LD as a way to be more responsive to student self-identified goals

    Cumulative and Differential Effects of Early Child Care and Middle Childhood Out-of-School Time on Adolescent Functioning.

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    Effects associated with early child care and out-of-school time (OST) during middle childhood were examined in a large sample of U.S. adolescents (N = 958). Both higher quality early child care AND more epochs of organized activities (afterschool programs and extracurricular activities) during middle childhood were linked to higher academic achievement at age 15. Differential associations were found in the behavioral domain. Higher quality early child care was associated with fewer externalizing problems, whereas more hours of early child care was linked to greater impulsivity. More epochs of organized activities was associated with greater social confidence. Relations between early child care and adolescent outcomes were not mediated or moderated by OST arrangements in middle childhood, consistent with independent, additive relations of these nonfamilial settings
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