13,148 research outputs found

    Genome editing in non-model organisms opens new horizons for comparative physiology

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    For almost 100 years, biologists have made fundamental discoveries using a handful of model organisms that are not representative of the rich diversity found in nature. The advent of CRISPR genome editing now opens up a wide range of new organisms to mechanistic investigation. This increases not only the taxonomic breadth of current research but also the scope of biological problems that are now amenable to study, such as population control of invasive species, management of disease vectors such as mosquitoes, the creation of chimeric animal hosts to grow human organs and even the possibility of resurrecting extinct species such as passenger pigeons and mammoths. Beyond these practical applications, work on non-model organisms enriches our basic understanding of the natural world. This special issue addresses a broad spectrum of biological problems in non-model organisms and highlights the utility of genome editing across levels of complexity from development and physiology to behaviour and evolution

    Applications of CFD and visualization techniques

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    In this paper, three applications are presented to illustrate current techniques for flow calculation and visualization. The first two applications use a commercial computational fluid dynamics (CFD) code, FLUENT, performed on a Cray Y-MP. The results are animated with the aid of data visualization software, apE. The third application simulates a particulate deposition pattern using techniques inspired by developments in nonlinear dynamical systems. These computations were performed on personal computers

    Basic studies of baroclinic flows

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    Computations were completed of transition curves in the conventional annulus, including hysteresis effect. The model GEOSIM was used to compute the transition between axisymmetric flow and baroclinic wave flow in the conventional annulus experiments. Thorough testing and documentation of the GEOSIM code were also completed. The Spacelab 3 results from the Geophysical Fluid Flow Cell (GFFC) were reviewed and numerical modeling was performed of many of the cases with horizontal temperature gradients as well as heating from below, with different rates of rotation. A numerical study of the lower transition to axisymmetric flow in the baroclinic annulus was performed using GEOSIM

    Basic studies of baroclinic flows

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    A fully nonlinear 3-dimensional numerical model (GEOSIM), previously developed and validated for several cases of geophysical fluid flow, has been used to investigate the dynamical behavior of laboratory experiments of fluid flows similar to those of the Earth's atmosphere. The phenomena investigated are amplitude vacillation, and the response of the fluid system to uneven heating and cooling. The previous year's work included hysteresis in the transition between axisymmetric and wave flow. Investigation is also continuing of the flows in the Geophysical Fluid Flow Cell (GFFC), a low-gravity Spacelab experiment. Much of the effort in the past year has been spent in validation of the model under a wide range of external parameters including nonlinear flow regimes. With the implementation of a 3-dimensional upwind differencing scheme, higher spectral resolution, and a shorter time step, the model has been found capable of predicting the majority of flow regimes observed in one complete series of baroclinic annulus experiments of Pfeffer and co-workers. Detailed analysis of amplitude vacillation has revealed that the phase splitting described in the laboratory experiments occurs in some but not all cases. Through the use of animation of the models output, a vivid 3-dimensional view of the phase splitting was shown to the audience of the Southeastern Geophysical Fluid Dynamics Conference in March of this year. A study on interannual variability was made using GEOSIM with periodic variations in the thermal forcing. Thus far, the model has not predicted a chaotic behavior as observed in the experiments, although there is a sensitivity in the wavenumber selection to the initial conditions. Work on this subject, and on annulus experiments with non-axisymmetric thermal heating, will continue. The comparison of GEOSIM's predictions will result from the Spacelab 3 GFFC experiments continued over the past year, on a 'back-burner' basis. At this point, the study (in the form of a draft of a journal article) is nearly completed. The results from GEOSIM compared very well with the experiments, and the use of the model allows the demonstration of flow mechanics that were not possible with the experimental data. For example, animation of the model output shows that the forking of the spiral bands is a transient phenomenon, due to the differential east-west propagation of convection bands from different latitudes

    The Metallicity and Reddening of Stars in the Inner Galactic Bulge

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    We present a preliminary analysis of K, J-K color magnitude diagrams (CMDs) for 7 different positions on or close to the minor axis of the Milky Way at Galactic latitudes between +0.1^\circ and -2.8^\circ. From the slopes of the (linear) giant branches in these CMDs we derive a dependence of on latitude for b between -0.8^\circ and -2.8^\circ of -0.085 \pm 0.033 dex/degree. When combined with the data from Tiede et al. we find for -0.8^\circ \leq b \leq -10.3^\circ the slope in is -0.064 \pm 0.012 dex/degree. An extrapolation to the Galactic Center predicts [Fe/H] = +0.034 \pm 0.053 dex. We also derive average values for the extinction in the K band (A_K) of between 2.15 and 0.27 for the inner bulge fields corresponding to average values of E(J-K) of between 3.46 and 0.44. There is a well defined linear relation between the average extinction for a field and the star-to-star scatter in the extinction for the stars within each field. This result suggests that the typical apparent angular scale size for an absorbing cloud is small compared with the field size (90\arcsec on a side). Finally, from an examination of the luminosity function of bright giants in each field we conclude that the young component of the stellar population observed near the Galactic center declines in density much more quickly than the overall bulge population and is undetectable beyond 1^\circ from the Galactic center.Comment: accepted for publication in Astron. Jour. Compressed file contains the text, 9 figures, and 6 tables prepared with AAS Latex macros v. 4.

    Economic Growth and Recession Time Periods: Their Effect Upon Pleasure Travelers Visiting Florida Theme Parks

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    Two tourism-oriented travel samples were drawn from recent time periods that represented economic growth (expansion) and recession cycles in the O: S. economy. Analysis suggests that during the recession period, a greater percentage of theme park visitors chose to travel by air. Second, theme park travelers were more likely to visit friends or fami4 during the recession period. Third, recession theme park travelers were 10 years older, on the average, than their rapid growth counterparts. The average age difference of theme park visitors was found to be significantly different during cyclical economic periods. Research findings support the need for additional studies that segment using generational market

    Business Traveler Behavior after the Great Recession

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    The recent “Great Recession” prompted traditional business travelers to alter typical travel spending habits. One apparent behavioral change for travelers, highlighted in the Bureau of Labor Statistics consumer expenditure data, identified travelers’ tendency to buy significantly more groceries after the recession. This multiyear, longitudinal study revealed that business travelers doubled the consumption of grocery items after the recession as a possible means for alleviating non-subsidized food and beverage expenses. The employed business person, whose travel expenditures are wholly or partially subsidized by an employer, also appeared to drastically reduce personal travel expenditures for traditionally non-subsidized purchases. This study suggests that business travelers’ food consumption, tourism expenditures, length of stay and shopping behavior were affected by the recent recession. In addition, the responsible agents for the travelers in this study appeared to apply a conventional strategy for reducing the recession’s impact on the profit margin by reducing the length of the trips

    Comparability of non-destructive moisture measurement techniques on masonry during simulated wetting

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    Detecting the presence of moisture in historical masonry is essential to understanding how a structure interacts with the environment, and diagnosing the potential for damage from a range of physical, chemical, and biological processes. In-situ, non-invasive diagnostic techniques have been developed in preference to methods that require irreversible modifications to a structure. These techniques include: electrical resistivity, microwaves, and infrared thermography. Independently, these approaches provide limited snapshots of surficial and internal moisture regimes; this project sought to assess the comparability of multiple techniques. Simulated post-rain spell drying was monitored over 48 h on limestone and sandstone monoliths in a controlled laboratory environment and also in ambient conditions on purpose-built masonry located in Oxfordshire, UK. Repeat measurements were taken using electrical resistance tomography (ERT), electrical and microwave moisture meters, and infrared thermography. Three aspects of comparability are discussed: i) data transformations and geological comparability, ii) depth-resolving meter readings, iii) the localised benefits of employing multiple technologies and instruments
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