The Early Evolution of Primordial Pair-Instability Supernovae

The observational signatures of the first cosmic explosions and their chemical imprint on second-generation stars both crucially depend on how heavy elements mix within the star at the earliest stages of the blast. We present numerical simulations of the early evolution of Population III pair-instability supernovae with the new adaptive mesh refinement code CASTRO. In stark contrast to 15 - 40 Msun core-collapse primordial supernovae, we find no mixing in most 150 - 250 Msun pair-instability supernovae out to times well after breakout from the surface of the star. This may be the key to determining the mass of the progenitor of a primeval supernova, because vigorous mixing will cause emission lines from heavy metals such as Fe and Ni to appear much sooner in the light curves of core-collapse supernovae than in those of pair-instability explosions. Our results also imply that unlike low-mass Pop III supernovae, whose collective metal yields can be directly compared to the chemical abundances of extremely metal-poor stars, further detailed numerical simulations will be required to determine the nucleosynthetic imprint of very massive Pop III stars on their direct descendants.Comment: submitted to ApJ, comments welcom

Energy Harvesting for Residential Microgrid Distributed Sensor Systems

Microgrids are localized, independent power grids that can operate while connected to the larger electrical grid. These systems make intelligent decisions regarding power management and use an array of components to monitor power generation, consumption, and environmental conditions. While this technology can save end users money, the complexity of installation and maintenance has limited the adoption of microgrids in residential spaces. To simplify this technology for end users, the next evolution of microgrid components includes sensors that are wireless and ambiently powered. Even with a microgrid installed, significant energy is wasted in residential spaces. To address this loss, energy harvesting circuits can be incorporated into microgrid sensors, enabling them to recapture otherwise wasted environmental energy. Light, heat, radio frequency (RF) energy, mechanical energy, and 60 Hz noise from power lines are all abundant in most residential spaces and can be harvested to power microgrid components. Equipping microgrid sensors with energy harvesters simplifies the end user experience by eliminating the need for cable routing. Implementing energy harvesting techniques results in a microgrid that is easier to deploy, cleaner, and requires less maintenance. Developing this type of sensor is not only feasible, but sensible and can be constructed using off-the-shelf components. My research led me to conclude that the most effective strategy for designing an energy harvesting sensor is to combine energy harvesting technologies with battery power. By delegating smaller loads away from the harvesting integrated circuit (IC), its full harvesting potential is utilized, maximizing energy collection for the power-hungry transmitter. Simultaneously, a small coin-cell battery can sustain the remaining components, ensuring over a decade of functionality. This thesis explores the feasibility and design of a hybrid battery and energy harvesting sensor. The developed system block diagram allows for the swapping of components within each block, catering to the varying needs of the end user. The system is data and energy-aware, allowing it to make intelligent decisions regarding data transmission and enable communication as reliable as that of a traditional wire-line powered sensor. The hybrid sensor module underwent testing with a small monocrystalline solar cell as its energy source, delivering consistent power throughout the testing period. It accumulated surplus energy in a super capacitor storage unit, ensuring the system’s reliable operation even at night when the energy source was not available. While the tests utilized a photovoltaic (PV) cell, the design accommodates any energy harvesting source that can generate a minimum of 40 µW of power

Addressing a global epidemic: Opportunities for adult education to assist suicide loss survivors

Globally 800,000 people die by suicide every year. The worldwide prevalence of suicide has led to an increase in suicide prevention educational programming, but suicide bereavement education is rarely addressed. The upward trend of suicide rates has direct implications at the personal, community, societal, and global levels. The purpose of this literature review is to bring together empirical studies of those bereaved by suicide from various fields, so that researchers in adult education have a direction for this much-needed area of exploration. Three themes emerged during this research: (a) unique bereavement challenges, (b) barriers to obtaining support, and (c) sources of effective support. The studies were conducted in the fields of death and dying, mental health, public health, nursing, and suicidology with only one study conducted in the field of adult education. The results of this literature review can serve as a starting point for synergistic endeavors between adult education researchers and scholars in these fields to create programing that will serve the needs of suicide loss survivors. Such endeavors will bridge the gap between adult education theories and praxis

Generalised Umbral Moonshine

Umbral moonshine describes an unexpected relation between 23 finite groups arising from lattice symmetries and special mock modular forms. It includes the Mathieu moonshine as a special case and can itself be viewed as an example of the more general moonshine phenomenon which connects finite groups and distinguished modular objects. In this paper we introduce the notion of generalised umbral moonshine, which includes the generalised Mathieu moonshine [Gaberdiel M.R., Persson D., Ronellenfitsch H., Volpato R., Commun. Number Theory Phys. 7 (2013), 145-223] as a special case, and provide supporting data for it. A central role is played by the deformed Drinfel'd (or quantum) double of each umbral finite group $G$, specified by a cohomology class in $H^3(G,U(1))$. We conjecture that in each of the 23 cases there exists a rule to assign an infinite-dimensional module for the deformed Drinfel'd double of the umbral finite group underlying the mock modular forms of umbral moonshine and generalised umbral moonshine. We also discuss the possible origin of the generalised umbral moonshine

Hexabromocyclododecane decreases the lytic function and ATP levels of human natural killer cells

This study investigates the effect of hexabromocyclododecane (HBCD) on the lytic function of human natural killer (NK) cells and on ATP levels in NK cells. NK cells are capable of lysing tumor cells, virally infected cells, and antibody-coated cells. HBCD is a brominated cyclic alkane used primarily as an additive flame retardant. If HBCD interferes with NK cell function, this could increase risk of tumor development and/or viral infection. NK cells were exposed to various concentrations of HBCD for 24 and 48 h and 6 days before determining lytic function and ATP levels. ATP levels and lytic function were also determined in NK cells that were exposed to HBCD for 1 h followed by 24 and 48 h, and 6 days in HBCD-free media. The results indicated that exposure of NK cells to 10 µm HBCD for 24 h causes a very significant decrease in both NK cell lytic function and ATP levels (93.5 and 90.5%, respectively). Exposure of NK cells to 10 µm HBCD for 1 h followed by 24 h in HBCD-free media showed a progressive and persistent loss of lytic function (89.3%) as well as a decrease in ATP levels (46.1%). The results indicate that HBCD exposures decreased lytic function as well as ATP levels. However, a decrease in lytic function was not necessarily accompanied by a similar decrease in ATP. Importantly, these results also indicate that a brief (1 h) exposure to HBCD causes a progressive loss of lytic function over a 6 day period