Assessing changes in avian communities

Grazing is a potentially powerful tool to address wildlife declines associated with land use conversion in the western United States. Grazing systems can be manipulated to achieve desired vegetation outcomes, preserve native habitat and economically benefit multiple stakeholders. As a result, systems designed to benefit native ecosystems are being widely implemented. However, the benefits of these grazing systems on many wildlife communities remain relatively unexplored. Songbirds provide an ideal study system to test these benefits because they continue to use native habitat that is currently grazed. Given limited time and resources, conservation practitioners often monitor a single focal species or a species of conservation concern. However, to effectively assess effects of grazing, it is essential to have reliable models to predict changes in abundance of multiple species exposed to natural or anthropogenic changes. Recent quantitative advances provide new methods to accurately measure the abundance of multiple species while accounting for one of the main sources of error in abundance surveys - imperfect detection. Multispecies abundance models (MSAM) use a Bayesian N-mixture structure, which relies on repeated counts, to estimate detection and calculate adjusted abundance estimates for multiple species. Current MSAMs still fail to account for false positives, the detection of an individual that is not present because of either misidentification or double count of another individual. False positives can inaccurately inflate abundance and biodiversity estimates. Nichols et al. (2000) provides a dependent-double observer (DDO) survey method to account for imperfect detection. Because it relies on two observers working collaboratively to identify individuals, the DDO method is suggested to reduce the occurrence of false positives. To date, the DDO approach has not been combined with MSAMs. I explored a derivation of the MSAM using the DDO survey method to create a multispecies dependent double-observer abundance (MDAM) model. I used the MDAM to explore how two widely used grazing systems, season-long and rest-rotation, affect the abundance of eight songbird species with varying reliance on grassland vegetation in a sagebrush ecosystem: Brewer’s sparrow (Spizella breweri), brown-headed cowbird (Molothrus ater), chestnut-collared longspur (Calcarius ornatus), horned lark (Eremophila alpestris), lark bunting (Calamospiza melanocorys), McCown\u27s longspur (Rhynchophanes mccownii), vesper sparrow (Pooecetes gramineus), and western meadowlark (Sturnella neglecta). I compared abundance of these eight songbird species on these two grazing systems in eastern Montana. My results suggest grassland and sagebrush associated species, many of which are of conservation concern, exhibit a response based on their reliance on grassland vegetation. Most grassland associated species were more abundant in season-long grazing than rest-rotation grazing systems (brown-headed cowbird, lark bunting, western meadowlark) or showed little difference between the two systems (chestnut-collared longspur, horned lark, vesper sparrow). In contrast, sagebrush associated species (Brewer’s sparrow) showed no difference in abundance between the two grazing systems. Although a grassland associated species, McCown’s longspur did not exhibit the same patterns as other grassland species and was more abundant on rest-rotation systems than season-long systems. These results suggest that grazing management may have the largest impact on grassland associated species. My findings suggest that multiple grazing systems on a landscape may be necessary to support a suite of songbird species with different vegetation requirements

The “broken escalator” phenomenon: Vestibular dizziness interferes with locomotor adaptation

BACKGROUND: Although vestibular lesions degrade postural control we do not know the relative contributions of the magnitude of the vestibular loss and subjective vestibular symptoms to locomotor adaptation. OBJECTIVE: To study how dizzy symptoms interfere with adaptive locomotor learning. METHODS: We examined patients with contrasting peripheral vestibular deficits, vestibular neuritis in the chronic stable phase (n = 20) and strongly symptomatic unilateral Meniere’s disease (n = 15), compared to age-matched healthy controls (n = 15). We measured locomotor adaptive learning using the “broken escalator” aftereffect, simulated on a motorised moving sled. RESULTS: Patients with Meniere’s disease had an enhanced “broken escalator” postural aftereffect. More generally, the size of the locomotor aftereffect was related to how symptomatic patients were across both groups. Contrastingly, the degree of peripheral vestibular loss was not correlated with symptom load or locomotor aftereffect size. During the MOVING trials, both patient groups had larger levels of instability (trunk sway) and reduced adaptation than normal controls. CONCLUSION: Dizziness symptoms influence locomotor adaptation and its subsequent expression through motor aftereffects. Given that the unsteadiness experienced during the “broken escalator” paradigm is internally driven, the enhanced aftereffect found represents a new type of self-generated postural challenge for vestibular/unsteady patients

Universality in escape from a modulated potential well

We show that the rate of activated escape $W$ from a periodically modulated potential displays scaling behavior versus modulation amplitude $A$. For adiabatic modulation of an optically trapped Brownian particle, measurements yield $\ln W\propto (A_{\rm c} - A)^{\mu}$ with $\mu = 1.5$. The theory gives $\mu=3/2$ in the adiabatic limit and predicts a crossover to $\mu=2$ scaling as $A$ approaches the bifurcation point where the metastable state disappears.Comment: 4 pages, 3 figure

Think Different: Applying the Old Macintosh Mantra to the Computability of the SUSY Auxiliary Field Problem

Starting with valise supermultiplets obtained from 0-branes plus field redefinitions, valise adinkra networks, and the "Garden Algebra," we discuss an architecture for algorithms that (starting from on-shell theories and, through a well-defined computation procedure), search for off-shell completions. We show in one dimension how to directly attack the notorious "off-shell auxiliary field" problem of supersymmetry with algorithms in the adinkra network-world formulation.Comment: 28 pages, 1 figur

Horizontal stress anisotropy and effective stress as regulator of coal seam gas zonation in the Sydney Basin, Australia

Coal seam gas zonation in the Sydney Basin, NSW, Australia is related to basin hydrodynamics and hydrochemical facies evolution along the flow path from the subcrop to the basin center. Biogenic methane corresponds with meteoric water under hydrostatic pressure and persists down to the top of the geopressured zone (~800 to 1000m). Thermogenic gases, including wet hydrocarbons, can reach up to relatively shallow horizons of less than 500-600m depth. In the transition zone between the top of the geopressured and base of the hydrostatic zone, a mixed water and gas regime prevails, comprising brackish waters, and gases of mixed biogenic, thermogenic and inorganic origins, including CO. Mechanisms for and the role of stress in the development of this layered hydrogeological and gas environment are investigated in this paper.The inverse relationship between effective horizontal stress and permeability in coals through regulation of cleat volumes is well documented, and there is evidence of regionally compartmentalized stress regimes with depth within the Sydney and other eastern Australian coal basins. This regional stress regime can be overprinted by the effect of localized geological features. It is hypothesized that the in situ stress regime plays an important role in the regulation of groundwater flow regimes and extents, resulting in the development of the reported gas content and compositional zonation.Analysis of regional gas and stress data obtained from public and private databases, as well as literature, supports this hypothesis. Changes in gas concentration and composition with depth correspond with discernable variations in horizontal stress anisotropy. Gas contents generally increase with depth down to a 'peak gas' horizon, below which concentrations decrease. This 'peak gas' zone is coincident with a horizontal stress anisotropy change from moderately high to low levels, associated with reverse to strike-slip faulting conditions, respectively. The stress release zone also marks the top of the thermogenic gas zone, identified by the first appearance of ethane in the vertical profile. This zone also hosts gases of mixed origins: biogenic, thermogenic and inorganic (CO) and represents a mixed (transitional) groundwater flow environment. The base of the mixed gas zone is the top of the 'geopressured-only' flow associated with thermogenic gases and is signaled by the return to high stress reverse faulting conditions below 850-900m depth in the Sydney Basin

A comparison of methods for the registration of tractographic fibre images

Diffusion tensor imaging (DTI) and tractography have opened up new avenues in neuroscience. As most applications require precise spatial localization of the fibre images, image registration is an important area of research. Registration is usually performed prior to tractography. However more reliable images could be produced if a viable registration can be performed post tractography. This study shows two available techniques for direct registration of fibre images and explores novel adaptations of these. The methods register volume images derived from the fibres, and reapply the transformation from these registrations to the fibre images. The first method is a local affine registration and the second is a global affine registration. The local affine method produced superior results