Alien Registration- Robichaud, Mary M. (Dexter, Penobscot County)

https://digitalmaine.com/alien_docs/11027/thumbnail.jp

Alien Registration- Robichaud, Jane M. (Orono, Penobscot County)

https://digitalmaine.com/alien_docs/5951/thumbnail.jp

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

Order Recall in Verbal Short-Term Memory is Influenced by Semantic Activation

It has recently been suggested that order recall in short-term memory tasks is influenced by the level of activation of items in the lexico-semantic network. According to the Activated Network view, increasing the level of activation of an item would increase the probability of observing a migration of the item toward the beginning of the list (Poirier et al., 2015). We tested this prediction by manipulating the orthographic neighbourhood of to-be-recalled items. In Experiment 1, the first three items of a 7-item list were orthographic neighbours of the target item in Position 5. As predicted, at recall, the target item migrated more toward the beginning of the list than control items. In Experiment 2, all list items were orthographic neighbours of the target item located on Position 4, 5, or 6. Compared to control items, the target item migrated more toward the beginning than the end of the list

Development and Evaluation of High Resolution Simulation Tools to Improve Fire Weather Forecasts

Fire weather forecasts rely on numerical weather simulations where the grid size is 4 km x 4 km or larger. In areas of complex terrain, this model resolution will not capture the details of wind flows associated with complicated topography. Wind channeling in valleys, wind speed-up over mountains and ridges, and enhanced turbulence associated with rough terrain and tall forest canopies are poorly represented in current weather model applications. A number of numerical wind flow models have been developed for simulating winds at high resolution; however, there are limited observational data available at the spatial scales appropriate for evaluating these types of models. In response to this need for high resolution validation data, we collected wind measurements at very high spatial resolution over a range of meteorological conditions from three different types of terrain/landcover features: an isolated mountain covered predominantly by grass and sagebrush, a steep river canyon covered predominantly by grass, and a dissected montane drainage with a tall forest canopy. We used data from the isolated mountain and the steep river canyon to evaluate surface wind predictions from routine weather forecasts and a high resolution wind simulation model, WindNinja, developed specifically for fire behavior applications. Data from the third field site will be used for future model evaluations planned to investigate the effect of tall forest canopies on surface wind predictions. Analyses of observations from the isolated mountain and steep river canyon sites indicate that operational weather model (i.e., with numerical grid resolutions of around 4 km or larger) wind predictions are not likely to be good predictors of local near-surface winds (i.e., at sub-grid scales) in complex terrain. Under periods of weak synoptic forcing, surface winds tended to be decoupled from large-scale flows, and under periods of strong synoptic forcing, variability in surface winds was sufficiently large due to terrain-induced mechanical effects that a large-scale mean flow would not be representative of surface winds at most locations on or within the terrain feature. These findings are reported in a manuscript titled “High Resolution Observations of the Near-Surface Wind Field over an Isolated Mountain and in a Steep River Canyon” submitted for publication in Atmospheric Chemistry and Physics. Links to the observed data from this effort as well as an online interface to query, visualize, summarize, and download subsets of the data are available at: http://www.firemodels.org/index.php/windninja-introduction/windninja-publications. Findings from the model evaluations work indicate that using WindNinja to downscale from numerical weather prediction (NWP) model winds can, in some cases, improve the accuracy of surface wind forecasts in complex terrain. Predictions of surface wind speeds and directions improved with downscaling via WindNinja when flow features induced by large scale effects were adequately captured by the NWP model used to initialize WindNinja. This suggests that WindNinja could be incorporated into current fire forecast methods to provide better short-term forecasts for fire management operations. These findings are reported in a manuscript titled “Downscaling Surface Wind Predictions from Numerical Weather Prediction Models in Complex Terrain with a Mass-consistent Wind Model” that will be submitted to the Journal of Applied Meteorology and Climatology later this spring

Development and Evaluation of High Resolution Simulation Tools to Improve Fire Weather Forecasts

Fire weather forecasts rely on numerical weather simulations where the grid size is 4 km x 4 km or larger. In areas of complex terrain, this model resolution will not capture the details of wind flows associated with complicated topography. Wind channeling in valleys, wind speed-up over mountains and ridges, and enhanced turbulence associated with rough terrain and tall forest canopies are poorly represented in current weather model applications. A number of numerical wind flow models have been developed for simulating winds at high resolution; however, there are limited observational data available at the spatial scales appropriate for evaluating these types of models. In response to this need for high resolution validation data, we collected wind measurements at very high spatial resolution over a range of meteorological conditions from three different types of terrain/landcover features: an isolated mountain covered predominantly by grass and sagebrush, a steep river canyon covered predominantly by grass, and a dissected montane drainage with a tall forest canopy. We used data from the isolated mountain and the steep river canyon to evaluate surface wind predictions from routine weather forecasts and a high resolution wind simulation model, WindNinja, developed specifically for fire behavior applications. Data from the third field site will be used for future model evaluations planned to investigate the effect of tall forest canopies on surface wind predictions. Analyses of observations from the isolated mountain and steep river canyon sites indicate that operational weather model (i.e., with numerical grid resolutions of around 4 km or larger) wind predictions are not likely to be good predictors of local near-surface winds (i.e., at sub-grid scales) in complex terrain. Under periods of weak synoptic forcing, surface winds tended to be decoupled from large-scale flows, and under periods of strong synoptic forcing, variability in surface winds was sufficiently large due to terrain-induced mechanical effects that a large-scale mean flow would not be representative of surface winds at most locations on or within the terrain feature. These findings are reported in a manuscript titled “High Resolution Observations of the Near-Surface Wind Field over an Isolated Mountain and in a Steep River Canyon” submitted for publication in Atmospheric Chemistry and Physics. Links to the observed data from this effort as well as an online interface to query, visualize, summarize, and download subsets of the data are available at: http://www.firemodels.org/index.php/windninja-introduction/windninja-publications. Findings from the model evaluations work indicate that using WindNinja to downscale from numerical weather prediction (NWP) model winds can, in some cases, improve the accuracy of surface wind forecasts in complex terrain. Predictions of surface wind speeds and directions improved with downscaling via WindNinja when flow features induced by large scale effects were adequately captured by the NWP model used to initialize WindNinja. This suggests that WindNinja could be incorporated into current fire forecast methods to provide better short-term forecasts for fire management operations. These findings are reported in a manuscript titled “Downscaling Surface Wind Predictions from Numerical Weather Prediction Models in Complex Terrain with a Mass-consistent Wind Model” that will be submitted to the Journal of Applied Meteorology and Climatology later this spring

Direct Detection of Products from the Pyrolysis of 2-Phenethyl Phenyl Ether

The pyrolysis of 2-phenethyl phenyl ether (PPE, C_6H_5C_2H_4OC_6H_5) in a hyperthermal nozzle (300-1350 °C) was studied to determine the importance of concerted and homolytic unimolecular decomposition pathways. Short residence times (<100 μs) and low concentrations in this reactor allowed the direct detection of the initial reaction products from thermolysis. Reactants, radicals, and most products were detected with photoionization (10.5 eV) time-of-flight mass spectrometry (PIMS). Detection of phenoxy radical, cyclopentadienyl radical, benzyl radical, and benzene suggest the formation of product by the homolytic scission of the C_6H_5C_2H_4-OC_6H_5 and C_6H_5CH_2-CH_2OC_6H_5 bonds. The detection of phenol and styrene suggests decomposition by a concerted reaction mechanism. Phenyl ethyl ether (PEE, C_6H_5OC_2H_5) pyrolysis was also studied using PIMS and using cryogenic matrix-isolated infrared spectroscopy (matrix-IR). The results for PEE also indicate the presence of both homolytic bond breaking and concerted decomposition reactions. Quantum mechanical calculations using CBS-QB3 were conducted, and the results were used with transition state theory (TST) to estimate the rate constants for the different reaction pathways. The results are consistent with the experimental measurements and suggest that the concerted retro-ene and Maccoll reactions are dominant at low temperatures (below 1000 °C), whereas the contribution of the C_6H_5C_2H_4-OC_6H_5 homolytic bond scission reaction increases at higher temperatures (above 1000 °C)

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

An optical tweezer array of ultracold polyatomic molecules

Polyatomic molecules have rich structural features that make them uniquely suited to applications in quantum information science, quantum simulation, ultracold chemistry, and searches for physics beyond the Standard Model. However, a key challenge is fully controlling both the internal quantum state and the motional degrees of freedom of the molecules. Here, we demonstrate the creation of an optical tweezer array of individual polyatomic molecules, CaOH, with quantum control of their internal quantum state. The complex quantum structure of CaOH results in a non-trivial dependence of the molecules' behavior on the tweezer light wavelength. We control this interaction and directly and nondestructively image individual molecules in the tweezer array with >90% fidelity. The molecules are manipulated at the single internal quantum state level, thus demonstrating coherent state control in a tweezer array. The platform demonstrated here will enable a variety of experiments using individual polyatomic molecules with arbitrary spatial arrangement.Comment: 11 pages, 6 figure