CHARTING A NEW (DIS)COURSE: DEFINITIONS, METAPHORS, AND IDENTITY IN POLARIZATION AND POLITICS

The United States is more politically divided than any other wealthy democracy in modern history. This thesis examines the role of discourse in the polarization process and suggests a way to change course. Using a social constructionist approach and an analytical framework focusing on definitions, metaphors, and identity, it analyzes the discourse of the Civil War and 9/11 to understand how these elements influence the understanding and outcomes of sociocultural events. It then examines the current political landscape, including the events at the Capitol on January 6, 2021, through the same discursive lens. This thesis finds that today’s political discourse is strikingly similar to that of the Civil War and 9/11, pitting the “true heirs” of the nation against an evil “other” using the same rhetorical devices. This similarity suggests that the language of division is consistent, and that the framework is broadly applicable. Given the catastrophic outcomes of the Civil War and 9/11 and the subsequent Global War on Terror (GWOT), the nation must take steps to change its discourse. This thesis concludes by providing recommendations that take advantage of the transformative potential of the framework’s components, which include pragmatic definitions, generative metaphors, and complex identities.Civilian, City of Tamarac Fire RescueApproved for public release. Distribution is unlimited

Impact of Line-of-Sight and Unequal Spatial Correlation on Uplink MU-MIMO Systems

Closed-form approximations of the expected per-terminal signal-to-interference-plus-noise-ratio (SINR) and ergodic sum spectral efficiency of a multiuser multiple-input multiple-output system are presented. Our analysis assumes spatially correlated Ricean fading channels with maximum-ratio combining on the uplink. Unlike previous studies, our model accounts for the presence of unequal correlation matrices, unequal Rice factors, as well as unequal link gains to each terminal. The derived approximations lend themselves to useful insights, special cases and demonstrate the aggregate impact of line-of-sight (LoS) and unequal correlation matrices. Numerical results show that while unequal correlation matrices enhance the expected SINR and ergodic sum spectral efficiency, the presence of strong LoS has an opposite effect. Our approximations are general and remain insensitive to changes in the system dimensions, signal-to-noise-ratios, LoS levels and unequal correlation levels.Comment: 4 pages, 2 figures, accepted for publication in the IEEE Wireless Communications Letters, Vol. 6, 201

Taphonomic evidence for Late Pleistocene transitions in coral reef community composition, San Salvador, Bahamas

Over the past 20 years, the composi­ tion of Caribbean coral reef communities has changed drastically. The ecology of modern reefs, however, has only been studied since the late 1950\u27s. Thus, only a thirty year data set on changes in coral community composi­ tion exists with which to assess the current faunal transition. The need for longer term data has been recognized by marine ecologists as essential for determining whether the cur­ rent transition is part of a long tenn cycle or itself is an unprecedented phenomenon. On Telephone Pole Reef, San Salva­ dor, Bahamas, a transition from Acropora cer­ vicornis dominance to that of Porites porites has been observed in recent years. Dead A. cervicornisa specimens found at this locality display high levels of taphonomic alteration, which may serve as a marker for prior transi­ tions of this type in other reefs. It is not known, however, if a transition of this nature occurred in the past. The fossil record provides precisely the database required for answering this ques­ tion. A detailed examination of the fossil reef at Cockburn Town, San Salvador, Bahamas, has been performed in order to evaluate whether it preserves evidence of community transitions analogous to those occurring today. Specimens of fossil corals were collected from six stratigraphic horizons and a variety of ta-phonomic were obtained. Although different styles of preservation characterize specific ho­ rizons in the fossil reef, evidence does not ex­ ist for a Pleistocene precedent for the transi­ tion currently observed offshore

Indistinguishability and Interference in the Coherent Control of Atomic and Molecular Processes

The subtle and fundamental issue of indistinguishability and interference between independent pathways to the same target state is examined in the context of coherent control of atomic and molecular processes, with emphasis placed on possible "which-way" information due to quantum entanglement established in the quantum dynamics. Because quantum interference between independent pathways to the same target state occurs only when the independent pathways are indistinguishable, it is first shown that creating useful coherence (as defined in the paper) between nondegenerate states of a molecule for subsequent quantum interference manipulation cannot be achieved by collisions between atoms or molecules that are prepared in momentum and energy eigenstates. Coherence can, however, be transferred from light fields to atoms or molecules. Using a particular coherent control scenario, it is shown that this coherence transfer and the subsequent coherent phase control can be readily realized by the most classical states of light, i.e., coherent states of light. It is further demonstrated that quantum states of light may suppress the extent of phase-sensitive coherent control by leaking out some which-way information while "incoherent interference control" scenarios proposed in the literature have automatically ensured the indistinguishability of multiple excitation pathways. The possibility of quantum coherence in photodissociation product states is also understood in terms of the disentanglement between photodissociation fragments. Results offer deeper insights into quantum coherence generation in atomic and molecular processes.Comment: 26 pages, based on one Chapter from first author's Ph.D thesis in 200

Nucleosynthesis during the Early History of the Solar System

Abundances in terrestrial and meteoritic matter indicate that the synthesis of D^2, Li^6, Li^7, Be^9, B^(10) and B^(11) and possibly C^(13) and N^(15) occurred during an intermediate stage in the early history of the solar system. In this intermediate stage, the planetary material had become largely separated, but not completely, from the hydrogen which was the main constituent of primitive solar material. Appropriate physical conditions were satisfied by solid planetesimals of dimensions from 1 to 50 metres consisting of silicates and oxides of the metals embedded in an icy matrix. The synthesis occurred through spallation and neutron reactions simultaneously induced in the outer layers of the planetesimals by the bombardment of high energy charged particles, mostly protons, accelerated in magnetic flares at the surface of the condensing Sun. The total particle energy was approximately 10^(45) ergs while the average energy was close to 500 MeV per nucleon. Recent studies of the abundance of lithium in young T Tauri stars serve as the primary astronomical evidence for this point of view. The observed abundances of lithium and beryllium in the surface of the Sun are discussed in terms of the astronomical and nuclear considerations brought forward. The isotope ratios D^2/H^1 = 1.5 × 10^(−4), Li^6/L^i7 = 0.08, and B^(10)/B^(11) = 0.23 are the basic data leading to the requirement that 10 per cent of terrestrial-meteoritic material was irradiated with a thermal neutron flux of 10^7 n/cm^2 s for an interval of 10^7 years. The importance of the (n, α) reactions on Li^6 and B^(10) is indicated by the relatively low abundances of these two nuclei. It is shown that the neutron flux was sufficient to produce the radioactive Pd^(107) and I^(129) necessary to account for the radiogenic Ag^(107) and Xe^(129) anomalies recently observed in meteorites. The short time interval, ∼ 6 × 10^7 years, required for the radioactive decays to be effective applies to the interval between the end of nucleosynthesis in the solar system and the termination of fractionation processes in the parent bodies of the meteorites. It is not necessary to postulate a short time interval between the last event of galactic nucleosynthesis and the formation of large, solid bodies in the solar nebula

Quantum mechanics explained

The physical motivation for the mathematical formalism of quantum mechanics is made clear and compelling by starting from an obvious fact - essentially, the stability of matter - and inquiring into its preconditions: what does it take to make this fact possible?Comment: 29 pages, 5 figures. v2: revised in response to referee comment

Towards More Accurate Molecular Dynamics Calculation of Thermal Conductivity. Case Study: GaN Bulk Crystals

Significant differences exist among literature for thermal conductivity of various systems computed using molecular dynamics simulation. In some cases, unphysical results, for example, negative thermal conductivity, have been found. Using GaN as an example case and the direct non-equilibrium method, extensive molecular dynamics simulations and Monte Carlo analysis of the results have been carried out to quantify the uncertainty level of the molecular dynamics methods and to identify the conditions that can yield sufficiently accurate calculations of thermal conductivity. We found that the errors of the calculations are mainly due to the statistical thermal fluctuations. Extrapolating results to the limit of an infinite-size system tend to magnify the errors and occasionally lead to unphysical results. The error in bulk estimates can be reduced by performing longer time averages using properly selected systems over a range of sample lengths. If the errors in the conductivity estimates associated with each of the sample lengths are kept below a certain threshold, the likelihood of obtaining unphysical bulk values becomes insignificant. Using a Monte-Carlo approach developed here, we have determined the probability distributions for the bulk thermal conductivities obtained using the direct method. We also have observed a nonlinear effect that can become a source of significant errors. For the extremely accurate results presented here, we predict a [0001] GaN thermal conductivity of 185 $\rm{W/K \cdot m}$ at 300 K, 102 $\rm{W/K \cdot m}$ at 500 K, and 74 $\rm{W/K \cdot m}$ at 800 K. Using the insights obtained in the work, we have achieved a corresponding error level (standard deviation) for the bulk (infinite sample length) GaN thermal conductivity of less than 10 $\rm{W/K \cdot m}$, 5 $\rm{W/K \cdot m}$, and 15 $\rm{W/K \cdot m}$ at 300 K, 500 K, and 800 K respectively

Fernandez Bay, San Salvador, Bahamas: A Natural Laboratory for Assessment of the Preservation of Coral Reef Community Structure

Reprinted from: James L. Carew (ed.), Proceedings of the 8th Symposium on the Geology of the Bahamas: San Salvador, Bahamian Field Statio

Comparison of Recent Coral Life and Death Assemblages to Pleistocene Reef Communities: Implications for Rapid Faunal Replacement on Recent Reefs

Marine ecologists and paleoecologists are increasingly recognizing that the Pleistocene and Holocene fossil record of coral reefs is the exclusive database from which an assessment of the long-term responses of reef communities to environmental perturbations may be obtained. The apparent persistence of coral communities in the face of intense fluctuations in sea level and sea surface temperature during glacial and interglacial stages of Pleistocene time is in marked contrast to dramatic fluctuations in reef community structure documented by short-term monitoring studies. We compared the taxonomic structure of live and dead coral communities on a modem patch reef currently undergoing a community transition to late Pleistocene facies exposed in the CockburnTown fossil coral reef. Multidimensional scaling revealed that specific taxa and colony growth forms characterize life, death, and fossil assemblages. The recent decline of thickets of Acropora cervicorn is is represented by their abundance in the death assemblage, while Porites porites dominates the coral life assemblage. Although additional study of Pleistocene reefal facies is required, the greater similarity of the death assemblage to the fossil assemblage suggests that the present Caribbean- wide decline of A. cervicornis is without a historical preceden

Identification of blue high proper motion objects in the Tycho-2 and 2MASS catalogues using Virtual Observatory tools

With available Virtual Observatory tools, we looked for new bright blue high proper motion objects in the entire sky: white dwarfs, hot subdwarfs, runaway OB stars, and early-type stars in nearby young moving groups. We performed an all-sky cross-match between the optical Tycho-2 and near-infrared 2MASS catalogues with Aladin, and selected objects with proper motions >50mas/yr and colours Vt-Ks<-0.5mag with TOPCAT. We also collected multi-wavelength photometry, constructed the spectral energy distributions and estimated effective temperatures from fits to atmospheric models with VOSA for the most interesting targets. We assembled a sample of 32 bright blue high proper motion objects, including ten sdO/B subdwarfs, nine DA white dwarfs, five young early-type stars (two of which are runaway stars), two blue horizontal branch stars, one star with poor information, and five objects reported for the first time in this work. These last five objects have magnitudes Bt~11.0-11.6mag, effective temperatures ~24,000-30,000K, and are located in the region of known white dwarfs and hot subdwarfs in a reduced proper motion-colour diagram. We confirmed the hot subdwarf nature of one of the new objects, Albus 5, with public far-ultraviolet spectroscopic data obtained with FUSE.Comment: Published in Astronomy & Astrophysic