Study of rotation curves of spiral galaxies with a scalar field dark matter model

In this work we study rotation curves of spiral galaxies using a model of dark matter based on a scalar-tensor theory of gravity. We show how to estimate the scalar field dark matter parameters using a sample of observed rotation curves.Comment: 6 pages, 2 figures. arXiv admin note: substantial text overlap with arXiv:1112.520

Nucleic acids enrichment of fungal pathogens to study host-pathogen interactions

Fungal infections, ranging from superficial to life-threatening infections, represent a major public health problem that affects 25% of the worldwide population. In this context, the study of host-pathogen interactions within the host is crucial to advance antifungal therapy. However, since fungal cells are usually outnumbered by host cells, the fungal transcriptome frequently remains uncovered. We compared three different methods to selectively lyse human cells from in vitro mixes, composed of Candida cells and peripheral blood mononuclear cells. In order to prevent transcriptional modification, the mixes were stored in RNAlater. We evaluated the enrichment of fungal cells through cell counting using microscopy and aimed to further enrich fungal nucleic acids by centrifugation and by reducing contaminant nucleic acids from the host. We verified the enrichment of fungal DNA and RNA through qPCR and RT-qPCR respectively and confirmed that the resulting RNA has high integrity scores, suitable for downstream applications. The enrichment method provided here, i.e., lysis with Buffer RLT followed by centrifugation, may contribute to increase the proportion of nucleic acids from fungi in clinical samples, thus promoting more comprehensive analysis of fungal transcriptional profiles. Although we focused on C. albicans, the enrichment may be applicable to other fungal pathogens

Correlation of drag reducing data in dilute polymer solutions

The purpose of this investigation was to obtain a correlation for drag reducing solutions in circular tubes under turbulent conditions. Data were taken for three polymer-solvent systems: polymethyl methacrylate V-100 (Mv ~ 110,000) in toluene, polyisobutylene L-200 (Mv ~ 4,700,000) in toluene, and polyisobutylene L-200 in cyclohexane. The data from the two polyisobutylene systems, together with other data on polymethyl methacrylate G (Mv ~ 1,500,000) in toluene and polyisobutylene L-80 (Mv ~ 860,000) in cyclohexane, were used to attempt to obtain the correlation. The V-100 solutions were not used because they were not drag reducing. The variables that were believed to affect drag, reduction were considered and three dimensionless groups were used as the correlating groups. These groups were: a generalized Reynolds Number (NRe\u27 ), a Deborah Number, which is the ratio of the relaxation time of the polymer molecules to a characteristic flow time of the system, and a friction factor ratio. Two different characteristic flow times were used: D/V and n/Tw],which gave rise to two Deborah Numbers. Also, three friction factor ratios were considered. The data were studied by plotting two of the groups and using the third one as a parameter. Several concentrations of each polymer-solvent system were studied individually and the relationships obtained were compared to attempt to obtain a correlation independent of concentration…. Several methods for predicting friction factors with some accuracy were developed, but these methods only applied to a given concentration of a system. A relationship between a modified shear stress and velocity that applied to all concentrations of a polymer-solvent system was also obtained, but this method- does not allow accurate predictions of pressure drops --Abstract, pages vii-viii

Relationship between bats and prairie-dog (Cynomys ludovicianus) colonies in Western Kansas

Although it is known that prairie dog colonies can increase biodiversity in the areas surrounding them, there is extraordinarily little known about the relationship between bats and black-tailed prairie dogs (Cynomys ludovicianus). In a recent study from the Front Range of Colorado, several bat species were found to be consistently flying around prairie dog colonies, presumably foraging due to increased insect diversity and abundance. Despite the importance of prairie dogs to the ecosystem, prairie dog colonies are usually eradicated due to the perception that they adversely impact cattle grazing. If insectivorous bats are attracted to prairie dog colonies in Kansas, it would add to the list of ecosystem services provided by prairie dogs. We conducted acoustic bat surveys, attempted to confirm acoustic detections with mist netting, and sampled insects within and adjacent to prairie dog colonies. We also used new radio tracking technologies to closely monitor bat use of prairie dog colonies. We anticipated that bats, including Western small-footed myotis, would be more active over prairie dog colonies compared to the surrounding grasslands without prairie dog colonies. Our findings support part of this prediction. Significantly more bat calls were recorded over prairie dog colonies compared to non-prairie dog colonies. However, there was no significant difference in Western-small footed myotis calls on or off prairie dog colonies. There was no significant difference between the insect biomass on prairie dog colonies and non-prairie dog areas. Since there is not enough data to support the hypothesis that prairie dog colonies have more insect biomass than non-prairie dog areas, it leaves a gap in knowledge and creates potential areas for further research to be conducted. This study highlights the important ecological relationship between prairie dogs and bats and suggests that higher presence of bats on prairie dog colonies could lead to economic benefits to the agricultural industry through the predation of agricultural pests

Turbulence measurements in drag reducing flow

Studies of the frequency response of hot-film wedge probes in viscoelastic fluids established their reliability as measuring devices and demonstrated that the objections raised by Metzner and Astarita (77) are not valid for wedge probes. The structure of turbulence in drag reducing soap and polymer solutions was studied using a hot-film wedge probe. Intensity of turbulence measurements in drag reducing fluids indicate that the structure of trubulence is strongly dependent on the condition of the solution. Rates of energy dissipation calculated at the center of the tube indicate that there is an increase in the rate of energy dissipated in the central core of the tube. This indicates that the basic mechanism for drag reduction appears to be the storage and diffusion of energy from the wall to the central core of the tube, as proposed by Walsh (122). Rates of energy dissipation at the center of the tube were correlated using the Deborah number as an indication of the degree of degradation of the solution. Comparisons of several commonly-used hot film probes in purely viscous fluids indicate that deviations of 20% for measured turbulence intensities can be obtained, due to effects of probe geometry; normalized energy spectra measured with the same probes were similar, even though the measured turbulence intensities were different. Comparisons of intensities of turbulence in drag reducing fluids measured with a total pressure probe and a bot-film wedge probe indicates that there are differences between the results obtained with these two types of probes, which can be attributed to viscoelastic effects on the pressure probe measurements --Abstract, pages ii-iv