The H I chronicles of LITTLE THINGS blue compact dwarf galaxies

Star formation occurs when the gas (mostly atomic hydrogen; H I) in a galaxy becomes disturbed, forming regions of high density gas, which then collapses to form stars. In dwarf galaxies it is still uncertain which processes contribute to star formation and how much they contribute to star formation. Blue compact dwarf (BCD) galaxies are low mass, low shear, gas rich galaxies that have high star formation rates when compared to other dwarf galaxies. What triggers the dense burst of star formation in BCDs but not other dwarfs is not well understood. It is often suggested that BCDs may have their starburst triggered by gravitational interactions with other galaxies, dwarf-dwarf galaxy mergers, or consumption of intergalactic gas. However, there are BCDs that appear isolated with respect to other galaxies, making an external disturbance unlikely.^ Here, I study six apparently isolated BCDs from the LITTLE THINGS sample in an attempt to understand what has triggered their burst of star formation. LITTLE THINGS is an H I survey of 41 dwarf galaxies. Each galaxy has high angular and velocity resolution H I data from the Very Large Array (VLA) telescope and ancillary stellar data. I use these data to study the detailed morphology and kinematics of each galaxy, looking for signatures of starburst triggers. In addition to the VLA data, I have collected Green Bank Telescope data for the six BCDs. These high sensitivity, low resolution data are used to search the surrounding area of each galaxy for extended emission and possible nearby companion galaxies.^ The VLA data show evidence that each BCD has likely experienced some form of external disturbance despite their apparent isolation. These external disturbances potentially seen in the sample include: ongoing/advanced dwarf-dwarf mergers, an interaction with an unknown external object, and external gas consumption. The GBT data result in no nearby, separate H I companions at the sensitivity of the data. These data therefore suggest that even though these BCDs appear isolated, they have not been evolving in isolation. It is possible that these external disturbances may have triggered the starbursts that defines them as BCDs.^

Phosphorus enrichment effects on interactions among the ecosystem components in a long-hydroperiod oligotrophic marsh in Everglades National Park

Hydrology and a history of oligotrophy unite the massive landscape comprising freshwater marsh in Everglades National Park. With restoration of water flow to the Everglades, phosphorus (P) enrichment, both from agricultural and domestic sources, may increase nutrient load to the marsh ecosystem. Previous research of P enrichment of Everglades soil, periphyton, and macrophytes revealed each of these ecosystem components responds to increased P loads with increased production and nutrient content. Interactions among these ecosystem components and how P affects the magnitude and direction of interaction are poorly understood and are the focus of my research. Here I present results of a two-year, two-factor experiment of P enrichment and manipulation in Everglades National Park. I quantified biomass, nutrient content, and production for periphyton and macrophyes and found macrophyte removal drives change in nutrient content, biomass, and production of periphyton. Periphyton removal did not appear to control macrophyte dynamics. Soil chemical and physical characteristics were explained primarily by site differences but there was an enrichment effect of soil porewater nitrite + nitrate, nitrite, and soluble reactive phosphorus. Flocculent materials production and depth were significantly affected by macrophyte removal where depth and production were significantly greater with the no macrophyte treatment. The dominant macrophyte of the marsh, Eleocharis cellulosa, increased more in the unenriched marsh than in the enriched marsh. The combination of these findings suggests that dynamics in floc and periphyton are controlled primarily by the presence of periphyton and that this relationship is significantly affected by low-level P enrichment. These results may be valuable in their application to both managers and policy makers who are involved in the Everglades restoration process. ^

Essays on international macroeconomics and conflict analysis

This dissertation addressed two broad problems in international macroeconomics and conflict analysis. The first problem in the first chapter looked at the behavior of exchange rate and its interaction with industry-level tradable goods prices for three countries, USA, UK and Japan. This question has important monetary policy implications. Here, I computed to what extent changes in exchange rate affected prices of consumer, producer, and export goods. I also studied the timing of these changes in these prices. My results, based on thirty-four industrial prices for USA, UK and Japan, supported the view that changes in exchange rates significantly affect prices of industrial and consumer goods. It also provided an insight to the underlying economic process that led to changes in relative prices. ^ In the second chapter, I explored the predictability of future inflation by incorporating shocks to exchange rates and clearly specified the transmission mechanisms that link exchange rates to industry-level consumer and producer prices. Employing a variety of linear and state-of-the-art nonlinear models, I also predicted growth rates of future prices. Comparing levels of inflation obtained from the above approaches showed superiority of the structural model incorporating the exchange rate pass-through effect. ^ The second broad issue addressed in the third chapter of the dissertation investigated the economic motives for conflict, manifested by rebellion and civil war for seventeen Latin American countries. Based on the analytical framework of Garfinkel, Skaperdas and Syropoulos (2004), I employed ordinal regressions and Markov switching for a panel of seventeen countries to identify trade and openness factors responsible for conflict occurrence and intensity. The results suggested that increased trade openness reduced high intensity domestic conflicts but overdependence on agricultural exports, along with a lack of income earning opportunities lead to more conflicts. Thereafter, using the Cox Proportional Hazard model I studied “conflict duration” and found that over-reliance on agricultural exports explained a major part of the length of conflicts in addition to various socio-political factors. ^

Distribution and ecology of amphibians and reptiles in a fragmented landscape, northeastern Bolivia

Habitat loss and fragmentation have been implicated as driving forces behind recent waves of extinction. The regional landscape where this study occurred is a mosaic of forest and grassland, and therefore provides an ideal system with which to investigate the implications of habitat patchiness for the distribution and ecology of organisms. Here I describe patterns of amphibian and reptile distribution among and within habitats at the study site, investigate associations between habitat and community structure, describe nested subset patterns on forest islands, and quantify the relationship between body size and density across ecological scales and taxonomic groups. ^ Species richness did not vary across habitats, between forest island isolation classes or between island edges and cores. In contrast, species composition varied at all three ecological scales, reflecting differences in the distribution of both forest and open-habitat affiliated species. Species composition was associated with multivariate habitat profiles, with differences occurring along the isolation gradient of forest islands rather than the area gradient. The relationship between species composition and habitat was stronger for amphibians than for reptiles, a pattern that may be ascribed to physiological differences between the two groups. Analysis of nested subset pattern of community structure indicated that species composition of islands is nested as a function of isolation. Four species whose distribution on forest islands seems to be dispersal-limited drive the relationship between nestedness and isolation. Although there were several examples of shifts in body size across spatial scales and taxonomic groups, body size was not associated with density as predicted by theory, which may reflect differences between real and habitat islands, or differential responses of poikilothermic vertebrates to changes in density relative to homeotherms. ^ Taken together, the strongest result to emerge from this research is the importance of isolation, rather than area, on community structure in this system. Much evidence suggested that different ecological groups of species show distinct patterns of distribution both within and among habitat types. This suggests that species distributions at this site are not the result of 'neutral' processes at the community level, but rather reflect fundamental differences in the ecology of component species. ^

The relationship between alkaloid-based chemical defenses and diet in dendrobatid poison frogs

Chemical defenses are common among organisms and represent some of the most complex adaptations for avoiding predation, yet our understanding of the ecological nature of these systems remains incomplete. Poison frogs are a group of chemically defended organisms that are dependent entirely on diet for chemical defense. In this study, I identified the dietary arthropods responsible for chemical defense in poison frogs, described spatial and temporal patterns in alkaloid composition of poison frogs, and established links between patterns of variation in alkaloid defense and arthropod diet in poison frogs. Identifying dietary sources and studying patterns of variation in alkaloid composition is fundamental to understanding the ecology and evolution of chemical defense in poison frogs. ^ The dendrobatid poison frog Oophaga pumilio shares many alkaloids in common with other poison frogs and is known to vary in alkaloid composition throughout its geographic range. I designed my dissertation to take advantage of these characteristics and use O. pumilio as a model species for the study of chemical defense in poison frogs. Here, I identified siphonotid millipedes as a source for spiropyrrolizidine alkaloids, formicine ants as a source for pumiliotoxin alkaloids, and oribatid mites as dietary sources for the majority of alkaloids found in poison frogs. I found that alkaloid composition varied spatially and temporally, on both small and large scales, within and among populations of O. pumilio. Alkaloid variation between populations was related to geographic distance, and closer populations tended to have alkaloid compositions more similar to each other than to distant populations. ^ The findings of my study suggest that oribatid mites are the most important dietary source of alkaloids in poison frogs. However, overall alkaloid defense in poison frogs is based on a combination of dietary arthropods, including mites, ants, millipedes, and beetles. Variation in chemical defenses of poison frogs is due to (1) spatial and temporal differences in the presence of alkaloids in certain arthropods and (2) differences in the availability of certain alkaloid-containing arthropods, which are likely the result of differences as well as successional changes in forest structure among locations and through time. ^

A Review of the Effects of Altered Hydrology and Salinity on Vertebrate Fauna and Their Habitats in Northeastern Florida Bay

Estuarine productivity is highly dependent on the freshwater sources of the estuary. In Florida Bay, Taylor Slough was historically the main source of fresh water. Beginning in about 1960, and culminating with the completion of the South Dade Conveyance System in 1984, water management practice began to change the quantity and distribution of flow from Taylor Slough into Northeastern Florida Bay. These practices altered salinity and hydrologic parameters that had measurable negative impacts on vertebrate fauna and their habitats. Here, I review those impacts from published and unpublished literature and anecdotal observations. Almost all vertebrates covered in this review have shown some form of population decline since 1984; most of the studies implicate declines in food resources as the main stressor on their populations. My conclusion is that the diversion of fresh water resulted in an ecological cascade starting with hydrologic stresses on primary then secondary producers culminating in population declines at the top of the food web.

Revolutionaries in Space? A Counter-Review of Interstellar

Should the radical Left interpret the Nolans' Interstellar as a tribute to (neo)liberal expansionism or should we view it as a cautionary tale about a future that is just around the corner, which won't be solved by worm holes or time travel? This review takes the latter position against the recent Jacobin review, which argues the former. Here, I show that Interstellar can be productively reinterpreted as a film about a series of things that will NOT save us from our-late-capitalist-selves.

French Truffles and Forest Transitions

Truffle production in France has declined by more than 90% over the last 100 years. Commonly cited causes include a massive rural exodus that led to more open canopy forests becoming less intensively managed and reverting to closed canopy forests, the latter which do not favor truffle production. Scholars have labeled such a process as a forest transition, when a location goes from previously losing forest cover to regrowth and net gains in forest cover. Scholars have single out France as a place with a marked forest transition. Commonly these increases in forest cover are assumed to be a beneficial public good. Here, I question if it is accurate to view forest transitions as being universally beneficial, especially considering that this changing ecology has had strongly deleterious impacts on truffle production and those who rely on it for revenue. In this study I will use remote sensed images to examine if a forest transition did in fact occur in the department of Lot, France and what are the impacts forest trends have had on truffle cultivation. I will further estimates potential losses of revenue from truffle production which has resulted from any existing forest transition.

Vowels in the 305: A First Pass at Miami Latino English

In this paper, I present preliminary findings of the first-large scale, systematic study of English Latino vowels in Miami. Sociolinguistic interviews were conducted with 25 Miami-born participants: 10 Anglo Whites and 15 Latinos with varying degrees of Spanish fluency. Here I focus on the vowel quality (/i, ɪ, ai, æ, ɔ, u /) in the speech of the 2nd and 3rd generations to examine the nature of influence of Spanish on English in Miami over the past 60 years. I conduct an in-depth analysis of the vowel productions of two female speakers, Maria & Blaze, to show the range of vowel productions in Miami Latino English. The vocalic analysis is comprised of a minimum of 15 non-repeating tokens of each vowel. These vowels were extracted from interview data and analyzed for F1, F2, and F3 values using PRAAT. Two allophones of /æ/ were considered: pre-nasal and pre-non-nasal, since Latinos in other regions have shown to resist pre-nasal /æ/ raising (Thomas 2001).

Race Relations & Politics in Venezuela during Punto Fijo (1958 – 1998)

In 1998, Hugo Chávez Frías’ presidential candidacy brought race to national discussion in Venezuela for first time since 1945. For long, the country’s politics had abided by the myth of racial harmony and racial democracy. This approach pointed to institutional separation in the United States and Africa as examples of true racism. Latin America was largely void of such atrocities. Nonetheless, Chávez claimed the present political parties (Acción Democrática, Copei and Unión Republicana Democrática) disenfranchised the common, colored Venezuelan. He continued to assert the opposition’s racism during his presidency. And his political fanbase agrees. A variety of scholars have studied the break from Punto Fijo politics to the Bolivarian Revolution. Yet, few have linked the obvious class struggle to race. Here, I seek to explain how racial identity has shaped class identity in Venezuela by closely examining the Punto Fijo era (1958-1998). The essay begins with an overview of historical race relations, moving to the period in focus. Then, I examine systematic and institutional exclusion under Punto Fijo politics. The object is to understand the merit of Chávez’s racial claims since 1998. Hence, the study also sees democracy in action and the consequences of racial exclusion. The study will be accomplished through secondary research, considering the limitations brought by working abroad. In the end, this study serves as first step in analyzing the fall of what was once considered Latin America’s most durable democracy.

Race Relations & Politics in Venezuela during Punto Fijo (1958 – 1998)

In 1998, Hugo Chávez Frías’ presidential candidacy brought race to national discussion in Venezuela for first time since 1945. For long, the country’s politics had abided by the myth of racial harmony and racial democracy. This approach pointed to institutional separation in the United States and Africa as examples of true racism. Latin America was largely void of such atrocities. Nonetheless, Chávez claimed the present political parties (Acción Democrática, Copei and Unión Republicana Democrática) disenfranchised the common, colored Venezuelan. He continued to assert the opposition’s racism during his presidency. And his political fanbase agrees. A variety of scholars have studied the break from Punto Fijo politics to the Bolivarian Revolution. Yet, few have linked the obvious class struggle to race. Here, I seek to explain how racial identity has shaped class identity in Venezuela by closely examining the Punto Fijo era (1958-1998). The essay begins with an overview of historical race relations, moving to the period in focus. Then, I examine systematic and institutional exclusion under Punto Fijo politics. The object is to understand the merit of Chávez’s racial claims since 1998. Hence, the study also sees democracy in action and the consequences of racial exclusion. The study will be accomplished through secondary research, considering the limitations brought by working abroad. In the end, this study serves as first step in analyzing the fall of what was once considered Latin America’s most durable democracy.

Simply Genre Films: Extracting “King Lear” from “House of Strangers” and “Broken Lance"

The purpose of this thesis is to evaluate and refute Yvonne Griggs’ claims that the films “House of Strangers” (1949) and “Broken Lance” (1954) are as Griggs deems “genre-based adaptations” of William Shakespeare’s “King Lear.” I argue that the films, although they have some essential elements of “King Lear,” lack intentionality and reception, pivotal components in determining viability as a Shakespearean film adaptation. Using Griggs’ book as my critical background, I will show that these films are better classified under their respective genre categories, Western and film noir, not as “King Lear” genre adaptations. I will also suggest criteria for determining the level of canonicity of a “King Lear” film adaptation. Popularity of films does not determine validity, and a film does not need purported Shakespearean provenance to validate its ratings. Some films, like these, merely reference or pay homage to Shakespeare through use of essential elements of “King Lear”; here, I deem such affinities to be more unintentional than intentional.

Recent Changes in Central and Eastern Pacific El Niño

Recent research indicates that characteristics of El Niño and the Southern Oscillation (ENSO) have changed over the past several decades. Here, I examined different flavors of El Niño in the observational record and the recent changes in the character of El Niño events. The fundamental physical processes that drive ENSO were described and the Eastern Pacific (EP) and Central Pacific (CP) types or flavors of El Niño were defined. Using metrics from the peer-reviewed literature, I examined several historical data sets to interpret El Niño behavior from 1950-2010. A Monte Carlo Simulation was then applied to output from coupled model simulations to test the statistical significance of recent observations surrounding EP and CP El Niño. Results suggested that EP and CP El Niño had been occurring in a similar fashion over the past 60 years with natural variability, but no significant increase in CP El Niño behavior.