The Effects of Household Substrates on the Evaporation of Ignitable Liquids at Temperatures up to 210℃

In fire debris analysis, ignitable liquid residues are commonly identified using gas chromatography-mass spectrometry (GC-MS). The detection and identification of an ignitable liquid can help arson investigators determine whether a fire was intentional or accidental. To assist with the identification of ignitable liquid residues, chromatograms of questioned samples are typically compared to those of known ignitable liquids that have been weathered (evaporated) to different extents. Practitioners typically perform such weathering at room temperature and to a limited number of extents of weathering, so their database of weathered residues is likely to deviate markedly from casework residues. The ultimate goal of this project is to assist fire investigations by providing a stronger scientific basis for the observed weathering of ignitable liquid residues in casework samples. The experiments were designed to elucidate the effects of three different weathering factors on the distribution of residues: 1) the temperature at which weathering occurs, and 2) the porosity of the substrate, and 3) the penetration depth of an ignitable liquid in the substrate. A nine-component synthetic gasoline simulant was experimentally evaporated to different extents at different temperatures on four different substrates, including cotton fabric, nylon carpet, plywood and pine wood. Additional experiments were conducted in which 30-s or 30-min delays were implemented between spiking the gasoline simulant on each substrate and initiating the weathering at 210℃. The weathered residues in the different substrates were collected using solid-liquid extraction in pentane and analyzed using gas chromatography-mass spectrometry (GC-MS). The distribution of experimentally weathered residues were compared to a thermodynamic model that was previously developed by our group. In the absence of a substrate, the model provides accurate predictions of the relative peak areas for weathering conducted from 30-210℃ and up to 95% weathering. For example, the root mean squared error of predictions (RMSEPs) of the model was on the order of 2% for N=180 predicted peak areas at 210℃. Although the weathering temperature significantly alters the relative distribution of volatiles remaining in the weathered residues, the model accounts for the effect of temperature and the accuracy remains quite constant at ~2% between 30-210℃. The presence of a relatively non-porous substrate like cotton fabric had a small effect on the accuracy of the model; the RMSEPs increased to ~2.9% for N=117 predictions. However, in the presence of more porous substrates, like pine wood and plywood, the RMSEPs increased to a low of 3.7% for pine wood with no delay between spiking and weathering to 7.8% for plywood with a 30-minute delay. The prediction errors indicate that porous substrates like untreated wood prevent the volatile components from evaporating at their normal rates, and that the relative distribution of weathered residues hardly changes beyond 50% weathering. The results indicate that the entrapment of ignitable liquids in porous substrates make them appear less weathered than one would expect for a thermodynamic model

The Relationship Between Chronic Low Back Pain and Functional Movement

ABSTRACT Movements of the spine are different in those who have chronic low back pain (CLBP) compared to those who do not. By using inertial measurement units (IMUs), we assessed the angular acceleration of L5 and the sacrum in both healthy and CLBP individuals. PURPOSE: To determine if there is a difference in the movement patterns of L5 and the sacrum during spinal flexion in those with CLBP compared to those without. METHODS: Movement acceleration patterns were evaluated in 10 individuals between the ages of 35-65 years of age. 5 of the individuals reported having CLBP so they were categorized into the CLBP group and the other 5 were used as controls since they reported having no LBP. While the subjects were in the standing position, the IMUs were placed on the spinous process of L5 and S1. Participants were then asked to do forward flexion for 6 repetitions as quickly as they were able to. Angular acceleration was determined by using the output given by the gyroscope feature of the IMU. This feature measures changes in angular velocity. Changes in angular velocity were taken over changes in time to calculate angular acceleration ( ). RESULTS: Data showed that there was no statistical difference between the CLBP group and controls for both lumbar (p = 0.90) and sacral (p = 0.68) angular acceleration. CONCLUSION: Our study found that those with CLBP did not have a difference in how their L5 and sacrum moved during spinal flexion compared to those with no LBP. However, spinal flexion was the only movement measured. This could mean there is the possibility that if more movements of the spine were to be measured a difference in movement of L5 and the sacrum could be seen. The IMUs may also not be the best at measuring spinal movement, so a different method of measuring could better help us to determine if movement of the spine is different in CLBP individuals. Further research would need to be done to determine this

Co-expression of Gbeta 5 Enhances the Function of Two Ggamma Subunit-like Domain-containing Regulators of G Protein Signaling Proteins

Regulators of G protein signaling (RGS) stimulate the GTPase activity of G protein Galpha subunits and probably play additional roles. Some RGS proteins contain a Ggamma subunit-like (GGL) domain, which mediates a specific interaction with Gbeta 5. The role of such interactions in RGS function is unclear. RGS proteins can accelerate the kinetics of coupling of G protein-coupled receptors to G-protein-gated inwardly rectifying K+ (GIRK) channels. Therefore, we coupled m2-muscarinic acetylcholine receptors to GIRK channels in Xenopus oocytes to evaluate the effect of Gbeta 5 on RGS function. Co-expression of either RGS7 or RGS9 modestly accelerated GIRK channel kinetics. When Gbeta 5 was co-expressed with either RGS7 or RGS9, the acceleration of GIRK channel kinetics was strongly increased over that produced by RGS7 or RGS9 alone. RGS function was not enhanced by co-expression of Gbeta 1, and co-expression of Gbeta 5 alone had no effect on GIRK channel kinetics. Gbeta 5 did not modulate the function either of RGS4, an RGS protein that lacks a GGL domain, or of a functional RGS7 construct in which the GGL domain was omitted. Enhancement of RGS7 function by Gbeta 5 was not a consequence of an increase in the amount of plasma membrane or cytosolic RGS7 protein

RGS9-1 is required for normal inactivation of mouse cone phototransduction

Purpose: To test the hypothesis that Regulator of G-protein Signaling 9 (RGS9-1) is necessary for the normal inactivation of retinal cones. Methods: Mice having the gene RGS9-1 inactivated in both alleles (RGS9-1 -/-) were tested between the ages 8-10 weeks with electroretinographic (ERG) protocols that isolate cone-driven responses. Immunohistochemistry was performed with a primary antibody against RGS9-1 (anti-RGS9-1c), with the secondary conjugated to fluorescein isothiocyanate, and with rhodamine-conjugated peanut agglutinin. Results: (1) Immunohistochemistry showed RGS9-1 to be strongly expressed in the cones of wildtype (WT is C57BL/6) mice, but absent from the cones of RGS9-1 mice. (2) Cone-driven b-wave responses of dark-adapted RGS9-1 -/- mice had saturating amplitudes and sensitivities in the midwave and UV regions of the spectrum equal to or slightly greater than those of WT (C57BL/6) mice. (3) Cone-driven b-wave and a-wave responses of RGS9-1 -/- mice recovered much more slowly than those of WT after a strong conditioning flash: for a flash estimated to isomerize 1.2% of the M-cone pigment and 0.9% of the UV-cone pigment, recovery of 50% saturating amplitude was approximately 60-fold slower than in WT. Conclusions: (1) The amplitudes and sensitivities of the cone-driven responses indicate that cones and cone-driven neurons in RGS9-1 -/- mice have normal generator currents. (2) The greatly retarded recovery of cone-driven responses of RGS9-1 -/- mice relative to those of WT mice establishes that RGS9-1 is required for normal inactivation of the cone phototransduction cascades of both UV- and M-cones

THERMODYNAMIC APPROACH TO MODELING BIOFUELS PRODUCTION FROM MICROALGAE AND CYANOBACTERIA: THE ROLE OF ELECTROCHEMICAL POTENTIAL

Biofuels from 3rd-generation feed-stocks like microalgae and cyanobacteria are considered possible replacements of fossil fuels and a means to reduce emissions of the greenhouse gas CO2. There is a need to understand how to control microbial growth by manipulating environmental conditions to increase photosynthetic biofuel productivity and/or reduce manufacturing costs. A novel, non-equilibrium, bio-thermodynamic-based model was developed here to fundamentally link electrochemical potential, membrane electric potential, trans-membrane pH gradient, and external temperature with microbial proliferation and bio-system behaviour

RGS9, a GTPase Accelerator for Phototransduction

AbstractThe rod outer segment phototransduction GAP (GTPase-accelerating protein) has been identified as RGS9, a member of the RGS family of Gα GAPs. RGS9 mRNA expression is specific for photoreceptor cells, and RGS9 protein colocalizes with other phototransduction components to photoreceptor outer segment membranes. The RGS domain of RGS9 accelerates GTP hydrolysis by the visual G protein transducin (Gαt), and this acceleration is enhanced by the γ subunit of the phototransduction effector cGMP phosphodiesterase (PDEγ). These unique properties of RGS9 match those of the rod outer segment GAP and implicate it as a key element in the recovery phase of visual transduction

Transformer neural networks for human activity recognition

Master of ScienceDepartment of Computer ScienceArslan MunirHuman activity recognition is an emerging and important area in computer vision which seeks to determine the activity an individual or group of individuals are performing. The applications of this field ranges from generating highlight videos in sports, to intelligent surveillance and gesture recognition. Most activity recognition systems rely on a combination of convolutional neural networks (CNNs) to perform feature extraction from the data and recurrent neural networks (RNNs) to determine the time dependent nature of the data. This paper proposes and designs two transformer neural networks for human activity recognition: a recurrent transformer, a specialized neural network used to make predictions on sequences of data, as well as a vision transformer, a transformer optimized for extracting salient features from images, to improve speed and scalability of activity recognition. We have provided an extensive comparison of the proposed transformer neural networks with the contemporary CNN and RNN-based human activity recognition models in terms of speed and accuracy

Coevolutionary Signals in Metabotropic Glutamate Receptors Capture Residue Contacts and Long-Range Functional Interactions

Upon ligand binding to a G protein-coupled receptor, extracellular signals are transmitted into a cell through sets of residue interactions that translate ligand binding into structural rearrangements. These interactions needed for functions impose evolutionary constraints so that, on occasion, mutations in one position may be compensated by other mutations at functionally coupled positions. To quantify the impact of amino acid substitutions in the context of major evolutionary divergence in the G protein-coupled receptor subfamily of metabotropic glutamate receptors (mGluRs), we combined two phylogenetic-based algorithms, Evolutionary Trace and covariation Evolutionary Trace, to infer potential structure-function couplings and roles in mGluRs. We found a subset of evolutionarily important residues at known functional sites and evidence of coupling among distinct structural clusters in mGluR. In addition, experimental mutagenesis and functional assays confirmed that some highly covariant residues are coupled, revealing their synergy. Collectively, these findings inform a critical step toward understanding the molecular and structural basis of amino acid variation patterns within mGluRs and provide insight for drug development, protein engineering, and analysis of naturally occurring variants

Modules in the photoreceptor RGS9-1•Gβ5L GTPase-accelerating protein complex control effector coupling, GTPase acceleration, protein folding, and stability

RGS (regulators of G protein signaling proteins regulate G protein signaling by accelerating GTP hydrolysis, but little is known about regulation of GTPase-accelerating protein (GAP) activities or roles of domains and subunits outside the catalytic cores. RGS9-1 is the GAP required for rapid recovery of light responses in vertebrate photoreceptors and the only mammalian RGS protein with a defined physiological function. It belongs to an RGS subfamily whose members have multiple domains, including G gamma -like domains that bind G(beta5) proteins. Members of this subfamily play important roles in neuronal signaling, Within the GAP complex organized around the RGS domain of RGS9-1, we have identified a functional role for the G gamma -like-G(beta 5L) complex in regulation of GAP activity by an effector subunit, cGMP phosphodiesterase gamma and in protein folding and stability of RGS9-1, The C-terminal domain of RGS9-1 also plays a major role in conferring effector stimulation. The sequence of the RGS domain determines whether the sign of the effector effect will be positive or negative. These roles were observed in, vitro using full-length proteins or fragments for RGS9-1, RGS7, G(beta 5S), and G(beta 5s), The dependence of RGS9-1 on Gp, co-expression for folding, stability, and function has been confirmed in vivo using transgenic Xenopus laevis, These results reveal how multiple domains and regulatory polypeptides work together to fine tune G(t alpha) inactivation