Collisional Processes in Extrasolar Planetsimal Disks - Dust Clumps in Fomalhaut's Debris Disk

This paper presents a model for the outcome of collisions between planetesimals in a debris disk and assesses the impact of collisional processes on the structure and size distribution of the disk. The model is presented by its application to Fomalhaut's collisionally replenished dust disk; a recent 450 micron image of this disk shows a clump embedded within it with a flux ~5 per cent of the total. The following conclusions are drawn: (i) SED modelling is consistent with Fomalhaut's disk having a collisional cascade size distribution extending from bodies 0.2 m in diameter down to 7 micron-sized dust. (ii) Collisional lifetime arguments imply that the cascade starts with planetesimals 1.5-4 km in diameter. Any larger bodies must be predominantly primordial. (iii) Constraints on the timescale for the ignition of the cascade are consistent with these primordial planetesimals having a distribution that extends up to 1000km, resulting in a disk mass of 5-10 times the minimum mass solar nebula. (iv) The debris disk is expected to be intrinsically clumpy, since planetesimal collisions result in dust clumps. The intrinsic clumpiness of Fomalhaut's disk is below current detection limits, but could be detectable by future observatories such as the ALMA, and could provide the only way of determining the primordial planetesimal population. (v) The observed clump could have originated in a collision between two runaway planetesimals, both larger than 1400 km diameter. It is unlikely that we should witness such an event unless both the formation of these runaways and the ignition of the collisional cascade occurred within the last ~10 Myr. (vi) Another explanation for Fomalhaut's clump is that ~5 per cent of the planetesimals in the ring are trapped in 1:2 resonance with a planet orbiting at 80 AU.Comment: 21 pages, 13 figures, accepted by MNRA

Autonomous Cars, Electric and Hybrid Cars, and Ridesharing: Perceptions vs. Reality

Autonomous Cars, Electric and Hybrid Cars, and Ridesharing are all important new technologies in today\u27s society that can have potentially large impacts on the environment in the future. This study was conducted to determine the differences in perceptions of Gettysburg College students regarding Autonomous Cars, Electric and Hybrid Cars, and Ridesharing and the reality of these topics in the real world. This paper also compares the perceptions of Environmental Studies majors/minors to the perceptions of other majors at Gettysburg College. The primary research was conducted by analyzing questions that were a part of a survey consisting of 16 questions which was administered to Gettysburg College students via Facebook class group pages and the Environmental Studies majors email alias. The study group consisted of 110 students with 31 of them being Environmental Studies majors/minors and 79 of them being non-Environmental Studies majors/minors. It was determined that there were no statistically significant differences between the Environmental Studies majors/minors and students that are other majors/minors at Gettysburg College. From our survey, we found that there is a distinct gap in knowledge on the current and future impacts on the environment from Autonomous Cars, Electric and Hybrid Cars, and Ridesharing. The questions that ask which power method produces more greenhouse gas emissions as well as the questions about the miles per gallon of participants’ personal vehicles were the most accurately answered. Overall, Gettysburg College students regardless of major or minor were found to have mostly inaccurate perceptions on the topics of Autonomous Cars, Electric and Hybrid Cars, and Ridesharing

Double Jeopardy and Punishment: Why an As Applied Approach, As Applied to Separation of Powers Doctrines, Is Unconstitutional

This Comment will argue that an as applied approach allows the executive branch, whether at the state or federal level, to encroach into the legislative realm by rendering a statute unconstitutional as a result of the way the statute is administered. Section II of this Comment will begin by examining the history of the as applied and on its face double jeopardy approaches during the last 20 years. After a close examination of the decisions in Halper and Hudson in sections II.B and II.C, this Comment will explain why the holding of Hudson, though correct in its result, was not based on sound reasoning. In section II.D, this Comment will examine the Young decision and its departure from the mandates of Hudson. With the Ninth Circuit\u27s holding in Young in direct conflict with the Washington State Supreme Court\u27s holdings in Cambpell and Turay, section III will argue that the United States Supreme Court should overturn Young on separation of powers grounds. Finally, section III will also address the differences between an as applied challenge in the double jeopardy context and an as applied challenge in other constitutional contexts

Hydrodynamic View of Wave-Packet Interference: Quantum Caves

Wave-packet interference is investigated within the complex quantum Hamilton-Jacobi formalism using a hydrodynamic description. Quantum interference leads to the formation of the topological structure of quantum caves in space-time Argand plots. These caves consist of the vortical and stagnation tubes originating from the isosurfaces of the amplitude of the wave function and its first derivative. Complex quantum trajectories display counterclockwise helical wrapping around the stagnation tubes and hyperbolic deflection near the vortical tubes. The string of alternating stagnation and vortical tubes is sufficient to generate divergent trajectories. Moreover, the average wrapping time for trajectories and the rotational rate of the nodal line in the complex plane can be used to define the lifetime for interference features.Comment: 4 pages, 3 figures (major revisions with respect to the previous version have been carried out

Double Jeopardy and Punishment: Why an As Applied Approach, As Applied to Separation of Powers Doctrines, Is Unconstitutional

This Comment will argue that an as applied approach allows the executive branch, whether at the state or federal level, to encroach into the legislative realm by rendering a statute unconstitutional as a result of the way the statute is administered. Section II of this Comment will begin by examining the history of the as applied and on its face double jeopardy approaches during the last 20 years. After a close examination of the decisions in Halper and Hudson in sections II.B and II.C, this Comment will explain why the holding of Hudson, though correct in its result, was not based on sound reasoning. In section II.D, this Comment will examine the Young decision and its departure from the mandates of Hudson. With the Ninth Circuit\u27s holding in Young in direct conflict with the Washington State Supreme Court\u27s holdings in Cambpell and Turay, section III will argue that the United States Supreme Court should overturn Young on separation of powers grounds. Finally, section III will also address the differences between an as applied challenge in the double jeopardy context and an as applied challenge in other constitutional contexts

What was under the McMartin Preschool? A review and behavioral analysis of the tunnels find

The McMartin Preschool child abuse case began in 1983 in Manhattan Beach, California, and was one of the most visible cases in history. Although two trials were conducted and no convictions were obtained, some individuals continue to believe that dozens of children were sexually abused at the preschool. In 1990 an archeologist was hired to determine whether tunnels had existed under the school because some of the children had alleged that some of their abuse took place in tunnels under the building. The archeologist’s report was issued in 1993. It concluded that evidence of back-filled tunnels had been found. This critical analysis of the archeologist’s report concludes otherwise, that what the archeologist found was actually the filled-in remains of a rural family’s trash pit that pre-dated construction of the school. Regarding artifacts discovered in soil under the preschool, alternative interpretations to those of the archeologist are given. A theoretical functional analysis of the variables that may have accounted for the archeologist’s evident misinterpretation is presented

When we were Boy Scouts

Before I was old enough to be a Boy Scout, I yearned in vain to join my scoutmaster-dad as he departed on day hikes and weekend camping trips with the boy and other leaders of Troop 146 in St. Albans. When I moved out of the Cub Scouts at age 11, at last I was in Dad\u27s troop. Today, I recall those times with my father as a special part of my life