Near-Infrared Kinetic Spectroscopy of the HO_2 and C_2H_5O_2 Self-Reactions and Cross Reactions

The self-reactions and cross reactions of the peroxy radicals HO_2 and C_2H_5O_2 and HO_2 were monitored using simultaneous independent spectroscopic probes to observe each radical species. Wavelength modulation (WM) near-infrared (NIR) spectroscopy was used to detect HO_2, and UV absorption monitored HO_2 and C_2H_5O_2. The temperature dependences of these reactions were investigated over a range of interest to tropospheric chemistry, 221−296 K. The Arrhenius expression determined for the cross reaction, k_2(T) = (6.01^(+1.95)_(−1.47)) × 10^(−13) exp((638 ± 73)/T) cm^3 molecules^(−1) s^(−1) is in agreement with other work from the literature. The measurements of the HO_2 self-reaction agreed with previous work from this lab and were not further refined.(1) The C_2H_5O_2 self-reaction is complicated by secondary production of HO_2. This experiment performed the first direct measurement of the self-reaction rate constant, as well as the branching fraction to the radical channel, in part by measurement of the secondary HO_2. The Arrhenius expression for the self-reaction rate constant is k_3(T) = (1.29^(+0.34)_(−0.27)) × 10^(−13)exp((−23 ± 61)/T) cm^3 molecules^(−1) s^(−1), and the branching fraction value is α = 0.28 ± 0.06, independent of temperature. These values are in disagreement with previous measurements based on end product studies of the branching fraction. The results suggest that better characterization of the products from RO_2 self-reactions are required

Dating the Morris House: A Study of Heritage Value in Nova Scotia

In 2009, a group of concerned citizens in Halifax rallied to the banner of The Heritage Trust of Nova Scotia and the Ecology Action Centre to save an 18th century building from demolition. Their case for preserving the building hinged on its unique heritage value, it having formerly housed the office of Charles Morris,Nova Scotia’s first Chief Surveyor. Thanks to their efforts, the Morris House was temporarily relocated to a nearby vacant lot while a new apartment building gradually rose in its place. Although researchers had believed the Morris House pre-dated 1781, the year of Charles Morris’s death, its precise age was unknown at the time of the move. Through a combination of dendroarchaeological, cartographic, and documentary evidence, our research significantly alters previous understandings of the building’s history and complicates the narrative advanced by heritage advocates in its defense. In doing so, it also raises questions about the interface between empirical research and the socio-political factors influencing the determination of heritage value. En 2009, un groupe de citoyen s’est réuni sous les auspices de The Heritage Trust of Nova Scotia et The Ecology Action Centre concerné par la sauvegarde d’un bâtiment du 18e siècle menacé de démolition. Connu sous le nom de Morris Building en raison de liens possibles avec Charles Morris (père), premier chef arpenteur géomètre de la Nouvelle-Écosse, le bâtiment a été déplacé de sa position initiale du 1273 de la rue Hollis de Halifax à un site temporaire à proximité, car un bloc appartement devait y être construit. Bien que les spécialistes croyaient que le Morris Building datait d’avant 1781, son âge exact restait inconnu. Avec la combinaison de recherches dendroarchéologiques, cartographiques et documentaires, notre étude modifie significativement la compréhension de l’histoire du bâtiment et complique le tableau avancé par les défenseurs de la tradition dans la conservation de cet héritage. Ce faisant, la question est posée sur les chevauchements et relations entre la recherche empirique et les facteurs socio-politiques qui influencent la détermination de la valeur historique d’un site

Modeling Marsh‐Forest Boundary Transgression in Response to Storms and Sea‐Level Rise

The lateral extent and vertical stability of salt marshes experiencing rising sea levels depend on interacting drivers and feedbacks with potential for nonlinear behaviors. A two‐dimensional transect model was developed to examine changes in marsh and upland forest lateral extent and to explore controls on marsh inland transgression. Model behavior demonstrates limited and abrupt forest retreat with long‐term upland boundary migration rates controlled by slope, sea‐level rise (SLR), high water events, and biotic‐abiotic interactions. For low to moderate upland slopes the landward marsh edge is controlled by the interaction of these inundation events and forest recovery resulting in punctuated transgressive events. As SLR rates increase, the importance of the timing and frequency of water‐level deviations diminishes, and migration rates revert back to a slope‐SLR‐dominated process

Development of a Surgical Workforce Access Team (SWAT) in the Battle Against COVID-19

In response to the COVID-19 pandemic, our vascular surgery division has implemented a 24/7 vascular access team to provide line placement services throughout our medical center. We believe this model allows us to maximize our skillset while providing an important service for the hospital during this crisis. Additionally, this model allows us to control our own workforce and preserve workforce availability in the likely event that some of our providers contract the disease

Rapid response tools and datasets for post-fire modeling: linking Earth Observations and process-based hydrological models to support post-fire remediation

Preparation is key to utilizing Earth Observations and process-based models to support post-wildfire mitigation. Post-fire flooding and erosion can pose a serious threat to life, property and municipal water supplies. Increased runoff and sediment delivery due to the loss of surface cover and fire-induced changes in soil properties are of great concern. Remediation plans and treatments must be developed and implemented before the first major storms in order to be effective. One of the primary sources of information for making remediation decisions is a soil burn severity map derived from Earth Observation data (typically Landsat) that reflects fire induced changes in vegetation and soil properties. Slope, soils, land cover and climate are also important parameters that need to be considered. Spatially-explicit process-based models can account for these parameters, but they are currently under-utilized relative to simpler, lumped models because they are difficult to set up and require spatially-explicit inputs (digital elevation models, soils, and land cover). Our goal is to make process-based models more accessible by preparing spatial inputs before a fire, so that datasets can be rapidly combined with soil burn severity maps and formatted for model use. We are building an online database (http://geodjango.mtri.org/geowepp /) for the continental United States that will allow users to upload soil burn severity maps. The soil burn severity map is combined with land cover and soil datasets to generate the spatial model inputs needed for hydrological modeling of burn scars. Datasets will be created to support hydrological models, post-fire debris flow models and a dry ravel model. Our overall vision for this project is that advanced GIS surface erosion and mass failure prediction tools will be readily available for post-fire analysis using spatial information from a single online site

In Vivo Clearance of Alpha-1 Acid Glycoprotein Is Influenced by the Extent of Its N-Linked Glycosylation and by Its Interaction with the Vessel Wall

Alpha-1 acid glycoprotein (AGP) is a highly glycosylated plasma protein that exerts vasoprotective effects. We hypothesized that AGP's N-linked glycans govern its rate of clearance from the circulation, and followed the disappearance of different forms of radiolabeled human AGP from the plasma of rabbits and mice. Enzymatic deglycosylation of human plasma-derived AGP (pdAGP) by Peptide: N-Glycosidase F yielded a mixture of differentially deglycosylated forms (PNGase-AGP), while the introduction of five Asn to Gln mutations in recombinant Pichia pastoris-derived AGP (rAGP-N(5)Q) eliminated N-linked glycosylation. PNGase-AGP was cleared from the rabbit circulation 9-fold, and rAGP-N(5)Q, 46-fold more rapidly than pdAGP, primarily via a renal route. Pichia pastoris-derived wild-type rAGP differed from pdAGP in expressing mannose-terminated glycans, and, like neuraminidase-treated pdAGP, was more rapidly removed from the rabbit circulation than rAGP-N(5)Q. Systemic hyaluronidase treatment of mice transiently decreased pdAGP clearance. AGP administration to mice reduced vascular binding of hyaluronic acid binding protein in the liver microcirculation and increased its plasma levels. Our results support a critical role of N-linked glycosylation of AGP in regulating its in vivo clearance and an influence of a hyaluronidase-sensitive component of the vessel wall on its transendothelial passage

Comparison of Methods for the Purification of Alpha-1 Acid Glycoprotein from Human Plasma

Alpha-1 acid glycoprotein (AGP) is a highly glycosylated, negatively charged plasma protein suggested to have anti-inflammatory and/or immunomodulatory activities. Purification of AGP could be simplified if methods that exploit its high solubility under chemically harsh conditions could be demonstrated to leave the protein in its native conformation. Procedures involving exposure of AGP to hot phenol or sulphosalicylic acid (SSA) were compared to solely chromatographic methods. Hot phenol-purified AGP was more rapidly cleared from mice in vivo following intravenous injection than chromatographically purified AGP. In contrast, SSA-purified AGP demonstrated an identical in vivo clearance profile and circular dichroism spectrum to chromatographically purified AGP. Similarly, no differences in susceptibility to enzymatic deglycosylation or reactivity with Sambucus nigra lectin were detected between AGP purified via the two methods. Incorporation of the SSA step in the purification scheme for AGP eliminated the need for a large (4 mL resin/mL of plasma) initial chromatographic step and simplified its purification without causing any detectable distortion in the conformation of the protein. Confirmation that this procedure is nondenaturing will simplify AGP purification and investigation of its possible biological roles in laboratory animals

Agreeing on what? creating joint accounts of strategic change

This paper addresses a fundamental conundrum at the heart of meaning-making: how are multiple meanings accommodated within a joint account, given the plurivocal nature of organizations? While a new strategic initiative introduces new meanings that must coexist within multiple prevailing meanings; studies on meaning-making processes place different emphases on the accommodation of such multiplicity within a joint account. Based on the findings from a longitudinal case study conducted in a university setting, we develop a framework that demonstrates two patterns of meaning-making on the basis of distinct micro processes of expanding, combining and reframing that are involved in the accomplishment of a joint account. Our study offers counter-intuitive insights into the way vested interests enable or constrain the construction of a joint account of meaning. In doing so, we contribute to knowledge about resistance, ambiguity and the role of agreement, or lack of agreement in constructing joint accounts within a plurivocal context

Protection from erosion following wildfire

Abstract. Erosion in the first year after a wildfire can be up to three orders of magnitude greater than the erosion from undisturbed forests. To mitigate potential postfire erosion, various erosion control treatments are applied on highly erodible areas with downstream resources in need of protection. Because postfire erosion rates generally decline by an order of magnitude for each year of recovery, effective erosion mitigation treatments are most needed during the first year or two after a fire. Postfire treatments include broadcast seeding, scarification and trenching, physical erosion barriers such as contour-felled logs and straw wattles, and mulching with wheat straw, wood straw, and hydromulch. This paper summarizes data from more than seven years of studies to evaluate the effectiveness of postfire erosion mitigation treatments at the hillslope and small watershed-scale in the western U.S. Results suggest that some mitigation treatments may help reduce erosion for some, but not all, rainfall events. Generally, mulching is more effective than seeding, scarifying, or erosion barriers. For small rainfall events, reduction in first year erosion rates have been measured for engineered wood straw and straw mulch (60 to 80%), contour-felled log erosion barriers (50 to 70%), and hydromulch (19%). Grass seeding treatments have little effect on first year erosion reduction. For intense rain events (I 10 greater than 40 mm h -1 ) there was little difference between treated and non-treated areas