An Investigation of the Airborne Particulate Matter Related Health Hazards Present in Makerspaces

Airborne particulate matter poses several health hazards ranging from pulmonary inflammation to cardiovascular disease. Particulate matter is produced through many fabrication processes common to makerspaces, such as 3D printing and laser cutting. The danger of these particles is worsened when makerspaces are retrofitted into spaces not designed with good ventilation or safety controls, such as libraries and public schools. This thesis evaluates the relationship between makerspaces and hazardous particle generation with both continuous and motion sensor controlled ventilation, showing that the latter creates unsafe working conditions. Both observational and controlled studies were conducted in Bucknell’s Mooney Lab makerspace monitoring particle concentration and size distributions. A model was created based upon this data to help predict particle concentration and removal rates under a wider range of conditions than studied here. Continuous ventilation reduced peak particle concentrations to a third of motion sensor controlled ventilation levels and brought concentrations back near baseline levels 3.5 times faster. Based upon the findings of this study, makerspaces should not be established in any location without a properly sized ventilation system or to run ventilation systems in any configuration other than continuous flow

Irrelevant Interactions without Composite Operators - A Remark on the Universality of Second Order Phase Transitions

We study the critical behaviour of symmetric $\phi^4_4$ theory including irrelevant terms of the form $\phi^{4+2n}/\Lambda_0^{2n}$ in the bare action, where $\Lambda_0$ is the UV cutoff (corresponding e.g. to the inverse lattice spacing for a spin system). The main technical tool is renormalization theory based on the flow equations of the renormalization group which permits to establish the required convergence statements in generality and rigour. As a consequence the effect of irrelevant terms on the critical behaviour may be studied to any order without using renormalization theory for composite operators. This is a technical simplification and seems preferable from the physical point of view. In this short note we restrict for simplicity to the symmetry class of the Ising model, i.e. one component $\phi^4_4$ theory. The method is general, however.Comment: 13 page

Electronic nematic correlations in the stress free tetragonal state of BaFe2−x_{2-x}Nix_{x}As2_{2}

We use transport and neutron scattering to study electronic, structural, and magnetic properties of the electron-doped BaFe$_{2-x}$Ni$_x$As$_2$ iron pnictides in the external stress free detwinned state. Using a specially designed in-situ mechanical detwinning device, we demonstrate that the in-plane resistivity anisotropy observed in the uniaxial strained tetragonal state of BaFe$_{2-x}$Ni$_x$As$_2$ below a temperature $T^\ast$, previously identified as a signature of the electronic nematic phase, is also present in the stress free tetragonal phase below $T^{\ast\ast}$ ($<T^\ast$). By carrying out neutron scattering measurements on BaFe$_2$As$_2$ and BaFe$_{1.97}$Ni$_{0.03}$As$_2$, we argue that the resistivity anisotropy in the stress free tetragonal state of iron pnictides arises from the magnetoelastic coupling associated with antiferromagnetic order. These results thus indicate that the local lattice distortion and nematic spin correlations are responsible for the resistivity anisotropy in the tetragonal state of iron pnictides.Comment: 5 pages, 4 figure

Epitaxial (111) Films of Cu, Ni, and CuxNi_xNi_yonα−Al on {\alpha}-Al_2OO_3$(0001) for Graphene Growth by Chemical Vapor Deposition

Films of (111)-textured Cu, Ni, and Cu$_x$Ni$_y$ were evaluated as substrates for chemical vapor deposition of graphene. A metal thickness of 400 nm to 700 nm was sputtered onto a substrate of $\alpha-$Al$_2$O$_3$(0001) at temperatures of 250 C to 650 C. The films were then annealed at 1000 C in a tube furnace. X-ray and electron backscatter diffraction measurements showed all films have (111) texture but have grains with in-plane orientations differing by $60^{\circ}$. The in-plane epitaxial relationship for all films was $[110]_{metal}$||$[10\bar{1}0]_{{Al}_{2}{O}_{3}}$. Reactive sputtering of Al in O$_2$ before metal deposition resulted in a single in-plane orientation over 97 % of the Ni film but had no significant effect on the Cu grain structure. Transmission electron microscopy showed a clean Ni/Al$_2$O$_3$ interface, confirmed the epitaxial relationship, and showed that formation of the $60^{\circ}$ twin grains was associated with features on the Al$_2$O$_3$ surface. Increasing total pressure and Cu vapor pressure during annealing decreased the roughness of Cu and and Cu$_x$Ni$_y$ films. Graphene grown on the Ni(111) films was more uniform than that grown on polycrystalline Ni/SiO$_2$ films, but still showed thickness variations on a much smaller length scale than the distance between grains

Design requirements for a cloud-based automated red team in a cyber range for security operations training

Competitions for students, novices, and professionals to practice hacking and cyber defense skills (Conklin 2005; White et al. 2010). In cyber defense competitions teams design, implement, manage, and defend a network of computers and services (Schepens and James 2003). Cyber defense competitions are great learning opportunities for students and professionals. Typically, as in the case of the National Collegiate Cyber Defense Competition (https://www.nationalccdc.org/), the competitions consist of multiple blue teams of contestants and multiple red teams that attacks the services and systems that blue team is trying to counteract. An automated attack system needs to be intelligent, have low overhead, be realistic, and be modular (Miller et al. 2018). The components of automated attack systems vary. A patent for a very high-level design of an automated penetration system uses simulators (virtual machines or software that mimics the behavior of computers or networks), an exploit database, storage for scenarios, configuration files, and a penetration testing framework (Futoransky et al. 2013). Other systems can simulate network and user traffic (Rossey et al. 2002). We have so far identified four high-level design requirements: 1) ability to perform many types of attacks, 2) ability to follow a good process, 3) possession of a high-level situational understanding of the scenario, and 4) ease of sanitation and reuse of the simulation. Our continued work will identify more design requirements and areas of research that are needed to further the technological abilities and efficiency of automated red team design

First Science Results From SOFIA/FORCAST: Super-Resolution Imaging of the S140 Cluster at 37\micron

We present 37\micron\ imaging of the S140 complex of infrared sources centered on IRS1 made with the FORCAST camera on SOFIA. These observations are the longest wavelength imaging to resolve clearly the three main sources seen at shorter wavelengths, IRS 1, 2 and 3, and are nearly at the diffraction limit of the 2.5-m telescope. We also obtained a small number of images at 11 and 31\micron\ that are useful for flux measurement. Our images cover the area of several strong sub-mm sources seen in the area -- SMM 1, 2, and 3 -- that are not coincident with any mid-infrared sources and are not visible in our longer wavelength imaging either. Our new observations confirm previous estimates of the relative dust optical depth and source luminosity for the components in this likely cluster of early B stars. We also investigate the use of super-resolution to go beyond the basic diffraction limit in imaging on SOFIA and find that the van Cittert algorithm, together with the "multi-resolution" technique, provides excellent results

(Non) Gauge Invariance of Wilsonian Effective Actions in (Supersymmetric) Gauge Theories : A Critical Discussion

We give a detailed critical discussion of the properties of Wilsonian effective actions, defined by integrating out all modes above a given scale $\mu$. In particular, we provide a precise and relatively convenient prescription how to implement the infrared cutoff $\mu$ in any loop integral that is manifestly Lorentz invariant and also preserves global linear symmetries such as e.g. supersymmetry. We discuss the issue of gauge invariance of effective actions in general and in particular when using background field gauge. Our prescription for the IR cutoff (as any such prescription) breaks the gauge symmetry. Using our prescription, we have explicitly computed, at one loop, many terms of the Wilsonian effective action for general gauge theories, involving bosonic and fermionic matter fields of arbitrary masses and in arbitrary representations, exhibiting the non-gauge invariant (as well as the gauge invariant) terms. However, for supersymmetric gauge theories all non-gauge invariant terms cancel within each supermultiplet. This is strong evidence that in supersymmetric gauge theories this indeed defines a Lorentz, susy and gauge invariant Wilsonian effective action. As a byproduct, we obtain the explicit one-loop Wilsonian couplings for all higher-derivative terms $F D^{2n}F$ in the effective action of arbitrary supersymmetric gauge theories.Comment: 39 pages, 3 figures; several comments in sect. 2.6 and references are adde

Critical Exponents without the Epsilon Expansion

We argue that the sharp-cutoff Wilson renormalization group provides a powerful tool for the analysis of second-order and weakly first-order phase transitions. In particular, in a computation no harder than the calculation of the 1-loop effective potential, we show that the Wilson RG yields the fixed point couplings and critical exponents of 3-dimensional $O(N)$ scalar field theory, with results close to those obtained in high-order \ep-% expansion and large-$N$ calculations. We discuss the prospects for an even more precise computation.Comment: 8 pages, CLNS 94/1279, late