The Shoreline Fringe Forest and Adjacent Peatlands of the Southern Central British Columbia Coast

Four distinct vegetation types are found in close proximity along an exposed section of the southern central coast of British Columbia. A coastal fringe of coniferous forest a few hundred metres wide is separated by a steep ecotone from an inland peatland-forest complex. The objectives of this study were (1) to describe the plant communities along the transition from forest to peatland, and (2) to identify some of the major environmental factors associated with those communities using indicator plant analysis. The coastal forest is dominated by Thuja plicata, Tsuga heterophylla, Picea sitchensis, and Chamaecyparis nootkatensis. Characteristic understory species include Gaultheria shallon and Blechnum spicant. Inland from the coastal forest are transitional forest stands with a species-rich understory including Cornus canadensis, Hylocomium splendens, and Vaccinium parvifolium. The peatlands are poor fens characterized by thickets of Pinus contorta and Chamaecyparis nootkatensis among open areas dominated by species such as Sphagnum sp., Empetrum nigrum, Juniperus communis, and bogs characterized by Myrica gale, Eriophorum angustifolium, and Sanguisorba officinalis. Indicator plant analysis identified differences in the ground surface materials, soil moisture and nutrient regime between the vegetation types. The general trend is for an increase in soil moisture from the forest vegetation to the peatlands and a concurrent change from the Mor humus forms that dominate the coastal forest floor to the surface groundwater table of the peatlands. These environmental differences between forest and peatland are likely related to the steeper slopes typically found in the fringe forest vegetation

Ecology and management of riparian zone vegetation along small coldwater streams in Northwestern Ontario

This thesis synthesizes three papers on the ecology of the riparian zone vegetation found along small coldwater streams in northwestern Ontario. The objectives of this thesis were 1 ) to describe the biodiversity and distribution and abundance o f riparian zone plant species and vegetation types along the longitudinal and lateral gradients, 2) to evaluate the current buffer zone guidelines by comparing the riparian plant community between undisturbed sites and sites with adjacent clearcuts and forest fire, and 3) to examine the changes in the plant community trait structure found over the riparian-upland ecotone. 1 ) The riparian zones of these streams are diverse, with a large proportion o f the regional flora, including some locally rare species, represented. The vegetation is predominantly either an Alnus incana-dominated swamp thicket or a Calamagrostis canadensis and Carex aquatilis-dominated meadow marsh. Variation along the longitudinal gradient is weak with few species distributions significantly related to watershed size. Meadow marsh vegetation, however, is concentrated in watersheds 1000ha in area and smaller, likely due to the preference of beaver for streams of those sizes for dam construction. The riparian vegetation is remarkably homogenous along the lateral gradient. There are no distinct vegetation bands within the riparian zone, though some riparian-specialist species are more abundant near the streambank and some upland species are more common near the riparian-upland ecotone. The shoreward extent of the riparian zone, the riparian-upland ecotone, is marked by a strong shift in species composition at the limit of flooding and saturated soils. 2) Riparian plant community composition was compared between sites that were undisturbed, sites where clear-cuts were separated from the riparian zone by a buffer of upland forest, and sites where a forest fire had burned to the riparian zone-upland ecotone. No significant differences in the overall abundance and distribution of species in the riparian vegetation were found between the three disturbance classes, though a small number of species appeared to increase in abundance at burn sites. These results demonstrate that disturbances in the upland forest do not seriously impact the riparian zone plant community, likely because the riparian species are adapted to a high-light environment and flooding disturbance. The environmental factors that increase in the riparian zone following removal of the adjacent canopy, including light levels, temperature, and wind penetration, do not appear to have a significant influence on the riparian zone vegetation. These results suggest that aspects o f the current riparian management guidelines in northwestern Ontario may need to be re-evaluated. 3) The changes in importance of a range of reproductive, physiological, and morphological plant traits were examined over the riparian-upland ecotone. Traits with especially striking changes over the ecotone included leaf type, pollination and dispersal vector, clonal growth form, and a persistent seed bank. These trait patterns were used to generate hypotheses of potential functional explanations for the changes in plant community structure across the ecotone. These results have significance for ecotone theory as they demonstrate that plant traits can have very similar patterns of change across ecotones to those observed for the abundance of many species. Relationships between traits that represent potential functional relationships or tradeoffs are identified. Finally, this analysis has some implications for the types of traits that should be included in further trait-matrix studies

World Interest in Diverse Native Plant Stands

The objective of this paper was to provide a brief overview of native plant use and development including examples of native plant research being conducted in Canada. There is increasing interest in native plants in various countries. Currently, native plants are used in reclamation, biomass biofuel production, forage seeding, habitat restoration, and water and soil conservation efforts. Many countries have active programs for native plant preservation and new germplasm development, but seed cost, seed quality, and ease of establishment are still challenges for large-scale use. Many improved native plant germplasms have been released in recent years. In some countries, legislation and/or regulations were introduced to encourage use of native plants by industry such as in mine reclamation

Discovery of New Ultracool White Dwarfs in the Sloan Digital Sky Survey

We report the discovery of five very cool white dwarfs in the Sloan Digital Sky Survey (SDSS). Four are ultracool, exhibiting strong collision induced absorption (CIA) from molecular hydrogen and are similar in color to the three previously known coolest white dwarfs, SDSS J1337+00, LHS 3250 and LHS 1402. The fifth, an ultracool white dwarf candidate, shows milder CIA flux suppression and has a color and spectral shape similar to WD 0346+246. All five new white dwarfs are faint (g > 18.9) and have significant proper motions. One of the new ultracool white dwarfs, SDSS J0947, appears to be in a binary system with a slightly warmer (T_{eff} ~ 5000K) white dwarf companion.Comment: 15 pages, 3 figures, submitted to ApJL. Higher resolution versions of finding charts are available at http://astro.uchicago.edu/~gates/findingchart

Maladaptive autonomic regulation in PTSD accelerates physiological aging

A core manifestation of post-traumatic stress disorder (PTSD) is a disconnection between physiological state and psychological or behavioral processes necessary to adequately respond to environmental demands. Patients with PTSD experience abnormal oscillations in autonomic states supporting either fight and flight behaviors or withdrawal, immobilization, and dissociation without an intervening “calm” state that would provide opportunities for positive social interactions. This defensive autonomic disposition is adaptive in dangerous and life threatening situations, but in the context of every-day life may lead to significant psychosocial distress and deteriorating social relationships. The perpetuation of these maladaptive autonomic responses may contribute to the development of comorbid mental health issues such as depression, loneliness, and hostility that further modify the nature of cardiovascular behavior in the context of internal and external stressors. Over time, changes in autonomic, endocrine, and immune function contribute to deteriorating health, which is potently expressed in brain dysfunction and cardiovascular disease. In this theoretical review paper, we present an overview of the literature on the chronic health effects of PTSD. We discuss the brain networks underlying PTSD in the context of autonomic efferent and afferent contributions and how disruption of these networks leads to poor health outcomes. Finally, we discuss treatment approaches based on our theoretical model of PTSD

Formation of Millisecond Pulsars from Accretion Induced Collapse and Constraints on Pulsar Gamma Ray Burst Models

We study accretion induced collapse of magnetized white dwarfs as an origin of millisecond pulsars. We apply magnetized accretion disk models to the pre-collapse accreting magnetic white dwarfs and calculate the white dwarf spin evolution. If the pulsar magnetic field results solely from the flux-frozen fossil white dwarf field, a typical millisecond pulsar is born with a field strength $\sim 10^{11}-10^{12}G$. The uncertainty in the field strength is mainly due to the uncertain physical parameters of the magnetized accretion disk models. A simple correlation between the pulsar spin $\Omega_*$ and the magnetic field $B_*$, $(\Omega_*/10^4s^{-1})\sim (B_{*}/10^{11}G)^{-4/5}$, is derived for a typical accretion rate \sim 5\times 10^{-8}M_{\sun}/yr. This correlation remains valid for a wide pre-collapse physical conditions unless the white dwarf spin and the binary orbit are synchronized prior to accretion induced collapse. We critically examine the possibility of spin-orbit synchronization in close binary systems. Using idealized homogeneous ellipsoid models, we compute the electromagnetic and gravitational wave emission from the millisecond pulsars and find that electromagnetic dipole emission remains nearly constant while millisecond pulsars may spin up rather than spin down as a result of gravitational wave emission. We also derive the physical conditions under which electromagnetic emission from millisecond pulsars formed by accretion induced collapse can be a source of cosmological gamma-ray bursts. We find that relativistic beaming of gamma-ray emission and precession of gamma-ray emitting jets are required unless the dipole magnetic field strengths are $>10^{15}$G; such strong dipole fields are in excess of those allowed from the accretion induced collapse formation process except in spin-orbit synchronization.Comment: 36 pages, AASLATEX, 4 ps figures, Ap

The Effects of Global Change Upon United States Air Quality

To understand more fully the effects of global changes on ambient concentrations of ozone and particulate matter with aerodynamic diameter smaller than 2.5 μm (PM2.5) in the United States (US), we conducted a comprehensive modeling effort to evaluate explicitly the effects of changes in climate, biogenic emissions, land use and global/regional anthropogenic emissions on ozone and PM2.5 concentrations and composition. Results from the ECHAM5 global climate model driven with the A1B emission scenario from the Intergovernmental Panel on Climate Change (IPCC) were downscaled using the Weather Research and Forecasting (WRF) model to provide regional meteorological fields. We developed air quality simulations using the Community Multiscale Air Quality Model (CMAQ) chemical transport model for two nested domains with 220 and 36 km horizontal grid cell resolution for a semi-hemispheric domain and a continental United States (US) domain, respectively. The semi-hemispheric domain was used to evaluate the impact of projected global emissions changes on US air quality. WRF meteorological fields were used to calculate current (2000s) and future (2050s) biogenic emissions using the Model of Emissions of Gases and Aerosols from Nature (MEGAN). For the semi-hemispheric domain CMAQ simulations, present-day global emissions inventories were used and projected to the 2050s based on the IPCC A1B scenario. Regional anthropogenic emissions were obtained from the US Environmental Protection Agency National Emission Inventory 2002 (EPA NEI2002) and projected to the future using the MARKet ALlocation (MARKAL) energy system model assuming a business as usual scenario that extends current decade emission regulations through 2050. Our results suggest that daily maximum 8 h average ozone (DM8O) concentrations will increase in a range between 2 to 12 parts per billion (ppb) across most of the continental US. The highest increase occurs in the South, Central and Midwest regions of the US due to increases in temperature, enhanced biogenic emissions and changes in land use. The model predicts an average increase of 1–6 ppb in DM8O due to projected increase in global emissions of ozone precursors. The effects of these factors are only partially offset by reductions in DM8O associated with decreasing US anthropogenic emissions. Increases in PM2.5 levels between 4 and 10 μg m−3 in the Northeast, Southeast, Midwest and South regions are mostly a result of increase in primary anthropogenic particulate matter (PM), enhanced biogenic emissions and land use changes. Changes in boundary conditions shift the composition but do not alter overall simulated PM2.5 mass concentrations

Faint High Latitude Carbon Stars Discovered by the Sloan Digital Sky Survey: Methods and Initial Results

We report the discovery of 39 Faint High Latitude Carbon Stars (FHLCs) from Sloan Digital Sky Survey commissioning data. The objects, each selected photometrically and verified spectroscopically, range over 16.6 < r* < 20.0, and show a diversity of temperatures as judged by both colors and NaD line strengths. At the completion of the Sloan Survey, there will be many hundred homogeneously selected and observed FHLCs in this sample. We present proper motion measures for each object, indicating that the sample is a mixture of extremely distant (>100 kpc) halo giant stars, useful for constraining halo dynamics, plus members of the recently-recognized exotic class of very nearby dwarf carbon (dC) stars. Motions, and thus dC classification, are inferred for 40-50 percent of the sample, depending on the level of statistical significance invoked. The new list of dC stars presented here, although selected from only a small fraction of the final SDSS, doubles the number of such objects found by all previous methods. (Abstract abridged).Comment: Accepted for publication in The Astronomical Journal, Vol. 124, Sep. 2002, 40 pages, 7 figures, AASTeX v5.

Development and Validation of a 28-gene Hypoxia-related Prognostic Signature for Localized Prostate Cancer.

BACKGROUND: Hypoxia is associated with a poor prognosis in prostate cancer. This work aimed to derive and validate a hypoxia-related mRNA signature for localized prostate cancer. METHOD: Hypoxia genes were identified in vitro via RNA-sequencing and combined with in vivo gene co-expression analysis to generate a signature. The signature was independently validated in eleven prostate cancer cohorts and a bladder cancer phase III randomized trial of radiotherapy alone or with carbogen and nicotinamide (CON). RESULTS: A 28-gene signature was derived. Patients with high signature scores had poorer biochemical recurrence free survivals in six of eight independent cohorts of prostatectomy-treated patients (Log rank test P \u3c .05), with borderline significances achieved in the other two (P \u3c .1). The signature also predicted biochemical recurrence in patients receiving post-prostatectomy radiotherapy (n = 130, P = .007) or definitive radiotherapy alone (n = 248, P = .035). Lastly, the signature predicted metastasis events in a pooled cohort (n = 631, P = .002). Prognostic significance remained after adjusting for clinic-pathological factors and commercially available prognostic signatures. The signature predicted benefit from hypoxia-modifying therapy in bladder cancer patients (intervention-by-signature interaction test P = .0026), where carbogen and nicotinamide was associated with improved survival only in hypoxic tumours. CONCLUSION: A 28-gene hypoxia signature has strong and independent prognostic value for prostate cancer patients