On the stability of forced flows with temperature dependent viscosities

This thesis considers the convective stability behaviour of two boundary layer flows:the rotating disk and the at plate. For both coordinate systems, the wall is isothermally heated and fluids with an inverse-linear temperature dependent viscosity are examined. An enforced axial flow is applied to the rotating disk, whilst a variable angle of incline is studied for the plate through solutions to the Falkner-Skan family of equations. For both coordinate systems, similarity solutions are obtained for the mean, laminar flow. It is found that temperature dependencies that reduce the wall viscosity result in a narrowing of the boundary layer for both the disk and the plate, whilst increasing the axial flow strength and angle of incline achieves a similar narrowing of the disk and plate boundary layers, respectively. Linearised stability equations are derived through small perturbations to these mean flows. The stability equations are solved by utilising a spectral method to obtain the disturbance eigen functions and plot curves of neutral stability. With the exception of a small range of flows, temperature dependent viscosity flows are found to be less stable than the temperature independent case in both coordinate systems, where temperature dependence values that produce high wall viscosities yield the least stable flows. Conversely, increasing axial flow strength and angle of incline both produce greater flow stability for their respective geometries. The transitional Reynolds number for these flows is then approximated through an eN type analysis, where it is found to vary in approximate concordance with the critical Reynolds number. Finally, the disturbance eigen functions are used to solve an energy balance integral. Examination of the component energy contributions shows that flow stability is affected exclusively through changes to the mean flow. Extension of this analysis for applications to Chemical Vapour Deposition (CVD) is also discussed.</div

The prehistory of public health - water and waste in the ancient Near East

The prehistory of public health - water and waste in the ancient Near Eas

Additional file 1: Table S1. of The UT family of MHC class I loci unique to non-eutherian mammals has limited polymorphism and tissue specific patterns of expression in the opossum

The numbers of alleles varies between 2 and 23, but overall low levels of polymorphism were found. (PDF 62 kb

Model flows for CVD: enforced axial flow and temperature dependent viscosity

We present a numerical study concerning the enforced axial flow of a fluid with temperature dependent viscosity over a rotating disk. It is found that temperature dependencies in the liquid viscosity range narrow the mean velocity profiles and expand the mean temperature profile, while gaseous viscosity behaviour has the reverse effect in both of these cases. Under moderate axial flow the radial, azimuthal and temperature profiles are all entrained closer to the disk surface and the effects of variable viscosity are diminished. A linear stability analysis is performed over an extended range of axial flow strengths and temperature dependencies. Increasing the viscosity temperature-dependence parameter results in both Type I and II modes initially stabilising, before reaching a turning point and destabilising again. Enforced axial flow results in a stabilising effect of the Type I mode for all viscosity temperature-dependencies measured. Weakly enforced axial flow initially destabilises the Type II mode, before restabilising with further increased axial flow strength. The application of the investigated effects are discussed in the context of a chemical vapor deposition reactor

Percent cover of <i>Watersipora</i> at depths of 6 m, 12 m, and 18 m on platform Gilda in 2001 and 2013 and on platforms Gail, Gina, and Grace in 2013.

<p><i>Watersipora</i> was absent from platforms Gail, Gina, and Grace in 2001. The percent cover is displayed as mean values ± one standard error.</p

(a) PDDs averaged over 12 years for scenario 1. (b) PDDs averaged over 12 years for scenario 2.

<p>White circles and squares identify the platforms and harbors respectively that are source sites, where particles are released. Black circles identify the platforms that are used only as destination sites.</p

The Effects of Anthropogenic Structures on Habitat Connectivity and the Potential Spread of Non-Native Invertebrate Species in the Offshore Environment

<div><p>Offshore structures provide habitat that could facilitate species range expansions and the introduction of non-native species into new geographic areas. Surveys of assemblages of seven offshore oil and gas platforms in the Santa Barbara Channel revealed a change in distribution of the non-native sessile invertebrate <i>Watersipora subtorquata</i>, a bryozoan with a planktonic larval duration (PLD) of 24 hours or less, from one platform in 2001 to four platforms in 2013. We use a three-dimensional biophysical model to assess whether larval dispersal via currents from harbors to platforms and among platforms is a plausible mechanism to explain the change in distribution of <i>Watersipora</i> and to predict potential spread to other platforms in the future. Hull fouling is another possible mechanism to explain the change in distribution of <i>Watersipora</i>. We find that larval dispersal via currents could account for the increase in distribution of <i>Watersipora</i> from one to four platforms and that <i>Watersipora</i> is unlikely to spread from these four platforms to additional platforms through larval dispersal. Our results also suggest that larvae with PLDs of 24 hours or less released from offshore platforms can attain much greater dispersal distances than larvae with PLDs of 24 hours or less released from nearshore habitat. We hypothesize that the enhanced dispersal distance of larvae released from offshore platforms is driven by a combination of the offshore hydrodynamic environment, larval behavior, and larval release above the seafloor.</p></div

Measuring Hair Cortisol Concentrations to Assess the Effect of Anthropogenic Impacts on Wild Chimpanzees (<i>Pan troglodytes</i>) - Fig 1

<p><b>Illustration of (a) waning and (b) nest age effect on hair cortisol concentration.</b> (a) Line plot illustrating hair cortisol concentrations (HCC) along four consecutive 1-cm-segments. Data are shown for a representative subsample from 12 chimpanzee sleeping nests with different nest age classes. HCC was significantly different between segments [<i>χ</i>²(3) = 27.7, <i>p</i> < 0.0001, <i>r</i>² = 0.07] with HCC decreasing towards the distal end of the hair shaft. (b) Boxplots with 1.5 IQR showing HCC from 181 sleeping nests depending on the age class of the nest during hair sampling. Planned contrasts indicated that HCC was significantly higher in new vs. recent and old nests [<i>t</i>(2) = 6.3, <i>p</i> < 0.0001, <i>r</i>² = 0.95] whereas HCC was only borderline significant between recent and old nests [<i>t</i>(2) = 1.85, <i>p</i> = 0.07, <i>r</i>² = 0.63].</p

The muscle morphology of elite sprint running

The influence of muscle morphology and strength characteristics on sprint running performance, especially at elite level, is unclear. PURPOSE: This study aimed to investigate the differences in muscle volumes and strength between male elite sprinters, sub-elite sprinters, and untrained controls; and assess the relationships of muscle volumes and strength with sprint performance. METHODS: Five elite sprinters (100 m seasons best [SBE100]: 10.10 ± 0.07 s), 26 sub-elite sprinters (SBE100: 10.80 ± 0.30s) and 11 untrained control participants underwent: 3T magnetic resonance imaging scans to determine the volume of 23 individual lower limb muscles/compartments and 5 functional muscle groups; and isometric strength assessment of lower body muscle groups. RESULTS: Total lower body muscularity was distinct between the groups (controls < sub-elite +20% < elite +48%). The hip extensors exhibited the largest muscle group differences/relationships (elite, +32% absolute and +15% relative [per kg] volume vs sub-elite; explaining 31-48% of the variability in SBE100), whereas the plantarflexors showed no differences between sprint groups. Individual muscle differences showed pronounced anatomical specificity (elite vs sub-elite, absolute volume range +57% to -9%). Three hip muscles were consistently larger in elite vs. sub-elite (TFL, sartorius, gluteus maximus; absolute +45-57% and relative volume +25-37%), and gluteus maximus volume alone explained 34-44% of the variance in SBE100. Isometric strength of several muscle groups was greater in both sprint groups than controls, but similar for the sprint groups and not related to SBE100. CONCLUSIONS: These findings demonstrate the pronounced inhomogeneity and anatomically specific muscularity required for fast sprinting, and provides novel, robust evidence that greater hip extensor and gluteus maximus volumes discriminate between elite and sub-elite sprinters and are strongly associated with sprinting performance

Potential connectivity matrix for scenario 2.

<p>Potential connectivity matrix for scenario 2.</p