Using Probe Data to Understand the Impact of the Covid-19 Pandemic on Roadway Safety

Following the onset of the COVID-19 pandemic there was an observed decrease in traffic safety in the United Sates. New England was no exception to this, with traffic fatality rates increasing in Maine and Connecticut. This increase was attributed to the possibility that drivers had more opportunities to speed following the implementation of COVID-19 stay-at-home orders on roads with drastically reduced volume and decreased speed enforcement. To determine the state of research into the pandemic\u27s effect on traffic safety around the world, an extensive critical review was conducted. The reviewed studies showed that roadways did indeed become less safe with increased crash rates, increased crash severities, and increased rates of drivers engaging in dangerous behavior such as aggressive driving, drunk driving, distracted driving, and speeding. The review also went further to examine the effects on bicycle and pedestrian safety as well as transit. These represent alternative modes to roadway safety, or in the case of bikes and pedestrians, interact with cars and roadways regularly. Examining how the other modes were affected by the pandemic can be important to finding out where gaps exist in the current level of research. Next, this thesis evaluates how speeding changed during and after the stay-at-home orders in the states of Maine and Connecticut. Emerging probe data were used along with mixed effect logistic regression models to find out how the odds of speeding were affected. The findings revealed that there was a significant increase in the odds of speeding by more than 10, 15, and 20 mph in both Maine and Connecticut, with a more pronounced effect in Connecticut. Operational data were combined with geometric characteristics of the roadway so we could also model how traffic densities, and the geometric characteristics of the roadways affect speeding. It was found that lower traffic densities, such as Level of Service (LOS) of A and B are associated with more speeding than greater traffic densities (LOS D or E). This shows a potential conflict between transportation agencies goals of improving roadway performance and safety as roadways that are less susceptible to jamming could be more susceptible to speeding. Lastly, this thesis evaluates the effect of the COVID-19 pandemic on crash occurrence. Random effect logit models are developed with all crashes (KABCO) and fatal-injury crashes (KABC). Speed data was included in the models in the forms of average hourly speed and the Coefficient of Variation (CV) of speed to capture speed variability. It was found that while average speed was not significant in most cases, the variability of speed was associated with increases in the odds of crashes. Furthermore, the models included dummy variables for 2021 and 2022, the post-pandemic periods. The dummies indicated that there were increases in the odds of crash occurrence post-covid for certain crash types and road types, as well as identifying a shift in crashes on urban roadways from morning onto off-peak and evening peak hours

A helium-3 refrigerator employing capillary confinement of liquid cryogen

A condensation refrigerator suitable for operation in a zero gravity space environment was constructed. The condensed liquid refrigerant is confined by surface tension inside a porous metal matrix. Helium-4 and helium-3 gases were condensed and held in a copper matrix. Evaporative cooling of confined liquid helium-4 resulted in a temperature of 1.4K. Using a zeolite adsorption pump external to the cryostat, a temperature of 0.6 K was achieved through evaporative cooling of liquid helium-3. The amount of time required for complete evaporation of a controlled mass of liquid helium-4 contained in the copper matrix was measured as a function of the applied background power. For heating powers below 18 mW the measured times are consistent with the normal boiling of the confined volume of liquid refrigerant. At background powers above 18 mW the rapid rise in the temperature of the copper matrix the signature of the absence of confined liquid occurs in a time a factor of two shorter than that expected on the basis of an extrapolation of the low power data

Two receptors are required for antibody-dependent enhancement of human immunodeficiency virus type 1 infection: CD4 and Fc gamma R

Evidence of antibody-dependent enhancement of human immunodeficiency virus type 1 (HIV-1) infection via Fc receptor (FcR) was published previously (A. Takeda, C. U. Tuazon, and F. A. Ennis, Science 242:580-583, 1988). To define the entry mechanism of HIV-1 complexed with anti-HIV-1 antibody, we attempted to determine the receptor molecules responsible for mediating enhancement of HIV-1 infection of monocytic cells. Monoclonal antibodies to FcRI for immunoglobulin G substantially blocked antibody-dependent enhancement of HIV-1 infection. Furthermore, we demonstrate a requirement for the CD4 molecule in antibody-enhanced HIV-1 infection via FcR. Soluble CD4 prevented infection by HIV-1 antibody-treated virus, and enhancement of infection of virus-antibody complexes was abrogated by a monoclonal antibody to CD4 (anti-Leu3a antibody). Treatment of human macrophages with an anti-CD4 antibody also inhibited antibody-enhanced HIV-1 infection of macrophages, supporting our contention that antibody-dependent enhancement of HIV-1 infection via FcR requires CD4 interaction with the virus glycoprotein

Characteristics of GABAergic and cholinergic neurons in perinuclear zone of mouse supraoptic nucleus

The perinuclear zone (PNZ) of the supraoptic nucleus (SON) contains some GABAergic and cholinergic neurons thought to innervate the SON proper. In mice expressing enhanced green fluorescent protein (eGFP) in association with glutamate decarboxylase (GAD)65 we found an abundance of GAD65-eGFP neurons in the PNZ, whereas in mice expressing GAD67-eGFP, there were few labeled PNZ neurons. In mice expressing choline acetyltransferase (ChAT)-eGFP, large, brightly fluorescent and small, dimly fluorescent ChAT-eGFP neurons were present in the PNZ. The small ChAT-eGFP and GAD65-eGFP neurons exhibited a low-threshold depolarizing potential consistent with a low-threshold spike, with little transient outward rectification. Large ChAT-eGFP neurons exhibited strong transient outward rectification and a large hyperpolarizing spike afterpotential, very similar to that of magnocellular vasopressin and oxytocin neurons. Thus the large soma and transient outward rectification of large ChAT-eGFP neurons suggest that these neurons would be difficult to distinguish from magnocellular SON neurons in dissociated preparations by these criteria. Large, but not small, ChAT-eGFP neurons were immunostained with ChAT antibody (AB144p). Reconstructed neurons revealed a few processes encroaching near and passing through the SON from all types but no clear evidence of a terminal axon arbor. Large ChAT-eGFP neurons were usually oriented vertically and had four or five dendrites with multiple branches and an axon with many collaterals and local arborizations. Small ChAT-eGFP neurons had a more restricted dendritic tree compared with parvocellular GAD65 neurons, the latter of which had long thin processes oriented mediolaterally. Thus many of the characteristics found previously in unidentified, small PNZ neurons are also found in identified GABAergic neurons and in a population of smaller ChAT-eGFP neurons

The Behavior of Granular Materials under Cyclic Shear

The design and development of a parallel plate shear cell for the study of large scale shear flows in granular materials is presented. The parallel plate geometry allows for shear studies without the effects of curvature found in the more common Couette experiments. A system of independently movable slats creates a well with side walls that deform in response to the motions of grains within the pack. This allows for true parallel plate shear with minimal interference from the containing geometry. The motions of the side walls also allow for a direct measurement of the velocity profile across the granular pack. Results are presented for applying this system to the study of transients in granular shear and for shear-induced crystallization. Initial shear profiles are found to vary from packing to packing, ranging from a linear profile across the entire system to an exponential decay with a width of approximately 6 bead diameters. As the system is sheared, the velocity profile becomes much sharper, resembling an exponential decay with a width of roughly 3 bead diameters. Further shearing produces velocity profiles which can no longer be fit to an exponential decay, but are better represented as a Gaussian decay or error function profile. Cyclic shear is found to produce large scale ordering of the granular pack, which has a profound impact on the shear profile. There exist periods of time in which there is slipping between layers as well as periods of time in which the layered particles lock together resulting in very little relative motion.Comment: 10 pages including 12 figure

Report of committee studying failure reporting in the SAGE and experimental subsectors

Includes: introduction; present failure reporting methods; reports proposed; analysis of status and failure reports; plan of action; conclusion; appendices; and references.Recommendations of the committee studying failure reporting, appointed at a meeting on 14 June 1955

Nuclear Shell Model by the Quantum Monte Carlo Diagonalization Method

The feasibility of shell-model calculations is radically extended by the Quantum Monte Carlo Diagonalization method with various essential improvements. The major improvements are made in the sampling for the generation of shell-model basis vectors, and in the restoration of symmetries such as angular momentum and isospin. Consequently the level structure of low-lying states can be studied with realistic interactions. After testing this method on $^{24}$Mg, we present first results for energy levels and $E2$ properties of $^{64}$Ge, indicating its large and $\gamma$-soft deformation.Comment: 12 pages, RevTex, 2 figures, to be published in Physical Review Letter

Japanese encephalitis virus-specific proliferative responses of human peripheral blood T lymphocytes

The T lymphocytes play an important role in prevention and recovery from viral infections. To characterize T lymphocyte responses to Japanese encephalitis (JE) virus infections, we analyzed JE virus-specific T lymphocytes in peripheral blood mononuclear cells (PBMC) obtained from seven JE patients and 10 vaccinees who had received a formalin-inactivated, purified JE virus vaccine (Biken vaccine). These PBMC were examined for proliferative responses against live JE virus, a glutaraldehyde-fixed lysate of cells infected with JE virus, and extracellular particles (EPs; subviral membrane vesicles released from cells infected with recombinant vaccinia viruses encoding the JE virus premembrane and envelope proteins). Japanese encephalitis virus-specific T cell proliferation was demonstrated with PBMC from both patients and vaccinees after stimulation with infectious JE virus or the lysate of JE virus-infected cells. Proliferating PBMC included CD4+ T lymphocytes and CD8+ T lymphocytes in responses to either form of JE viral antigens. Responses to EPs were observed only with PBMC from some American vaccinees whose PBMC also responded to the virus and lysate. These results indicate that JE virus infection and immunization with an inactivated JE vaccine induce JE virus-specific CD4+ and CD8+ T memory lymphocytes that can be induced to proliferate by infectious JE virus and noninfectious JE antigens