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Therefore, for the final portion of our project, we decided to test a completely new estimator called Rojo1. The Rojo1 estimator is a new estimator proposed by Rojo for measuring tail heaviness by estimating the tail index using concepts from the extreme value theory. The Rojo1 estimator is defined to be log(n)/log(Xn), where n is the sample size and Xn is the largest-order statistic. The Rojo1 estimator can be used in many applications, including finance and environmental science. We hoped to explore the accuracy of Rojo1 by testing the computational work and the theoretical properties. We have found that the estimator works well when looking at the bias and MSE of our estimates, and we found Rojo1 to be a useful estimator for tail indices of heavy-tailed distributions. We have just begun to understand the possibilities that Rojo1 can provide us for estimating tail indices; however, there is more
TESTING FOR TAIL BEHAVIOR WITH REFINED SPACINGSofia Velazquez1, Javier Rojo2, Kelsey McCabe3, Torey Tonche4.
Harvard College, Cambridge, MA, 2Rice University, Houston, TX, 3University of Arizona,Tuscon, AZ, 4St. Mary’s 1 University, TX.
The ideas of extreme spacing and blocking were applied to test the hypotheses about tail-heaviness of underlying distributions previously described by Rojo and Ott. The gap between the greatest observations of the underlying distribution was used in constructing a test statistic for tail heaviness. The tests were also run with blocked data, yielding a substantial increase in power. In the case of blocked data, a test statistic was found for each block and then all test statistics were combined into one. In an attempt to further improve Rojo and Ott’s method, a weighted sum of individual block test statistics was considered. Through a simulation in R, values from distributions were generated and then placed into blocks consisting of equal numbers of observations. Within each block, the values were ordered ascendingly and the difference between the two greatest values was used to calculate the test statistic for that block.
A weighted sum of all the test statistics was then used for the defining test statistic. While this new method did yield high power with certain distributions, it was not the case for all, and Rojo and Ott’s method of blocking without weights yielded better results. While this method has yet to prove a better option, further manipulation with the amount of blocks or the value of the weights for each block may yield a better system for classifying tail-heaviness. (This work was supported by the RUSIS project, Directed by Javier Rojo, through NSF REU site grant DMS-1156847 and NSA REU grant H98230-12-1-0284.)
THE DISCOVERY OF UNEXPECTED ULTRAVIOLET EMISSION FROM THE DETACHED SHELL AROUND THE
EVOLVED STAR U HYDRAEEmmanuel Sanchez1, Rodolfo Montez Jr.2, Sofia Ramstedt3, Keivan Stassun2.
Florida State University, Tallahassee, FL, 2Vanderbilt University, Nashville, TN, 3Uppsala University, Uppsala, SE.
1 Most of the ingredients necessary for life are produced in stars during the late stages of their life. During the late stage known as the asymptotic giant branch (AGB), carbon, oxygen, and nitrogen are produced and released into the universe via dense stellar winds. In the AGB star U Hydrae, a substantial amount of material seems to have been lost during a single episode which lead to the formation of a cold, detached shell made of carbon-rich dust. The cold dust emits primarily in the far infrared range of the electromagnetic spectrum, however, using ultraviolet observations taken by the Galaxy Evolution Explorer (GALEX) satellite, we have discovered energetic ultraviolet emission coming from the detached shell and the AGB star. The origin of this energetic emission from the cold, detached shell is unusual but may be due to shocks as the detached shell moves away from the star, excitation of hydrogen molecules, or scattering of light from nearby stars. We use imaging and photometric analysis of the ultraviolet emission to determine the origin of this emission. We intend to follow up this study with a wider sample to study the influence of such energetic emission on the enriched stellar material.
SCATTERED LIGHT MEASUREMENTS FOR ADVANCED LIGO’S OUTPUT MODE CLEANER MIRRORSAdrian Avila-Alvarez, Joshua Smith, Cinthia Padilla, Fabian Magaña-Sandoval.
California State University, Fullerton, Fullerton, CA.
The Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO), with sites in Livingston, Louisiana, and Hanford, Washington, and its international partners, Virgo, GEO600, and KAGRA, are being built to detect
QUASARS PROBING QUASARSJose Lopez, Jason Prochaska.
University of California, Santa Cruz, Santa Cruz, CA.
Quasars are the brightest objects in the Universe, and it is believed that they are powered through the infall of matter onto a supermassive black hole, which is at the center of a massive galaxy. They can be used to answer three of the most important research subjects being studied by cosmologists today: when and how was the universe reionized, how did supermassive black holes grow over cosmic time, and what shuts off star formation in massive elliptical galaxies.
These questions can be addressed by observing close pairs of quasars with an angular separation of less than 1’.
Quasars allow us to study the rarefied matter between Earth and the quasar that is in absorption. Through the use of spectroscopy, the redshift of these quasars can be obtained to answer the questions addressed above. Programs have been created which help us process data obtained at various observatories. We then go on to analyze the data and determine if there is any oxygen (OIII) present in those quasars in the infrared wavelength. The device we are currently working with, the Palomar TripleSpec, will allow us to pin down the redshifts of the background quasars.
THE CAUSES OF IN SITU METHYL CHLORINE ENHANCEMENT IN SOME ANTARCTIC ICE CORESIsis Frausto-Vicencio1, Kristal Verhulst2, Murat Aydin2, Eric Saltzman.
College of the Sequoias, Visalia, CA, 2University of California, Irvine, Irvine, CA.
1 Methyl chloride (CH3Cl) is a naturally occurring ozone-depleting gas. CH3Cl is the most abundant halocarbon in the atmosphere with a global mean abundance of 550 parts per trillion. The sources of CH3Cl are mainly natural including tropical vegetation, oceans, and biomass burning. CH3Cl is sequestered from the atmosphere primarily through reaction with hydroxide with additional loss via microbial degradation in soils and the oceans, resulting in an atmospheric lifetime of about one year. Ice cores can provide a long-term record of the natural variability of atmospheric CH3Cl. Atmospheric CH3Cl is well-preserved in polar ice cores at cold high-altitude sites. Measurements from warm sites provide evidence for in situ production of CH3Cl in ice cores. The goal of this study is to determine the potential causes of in situ CH3Cl production in some Antarctic ice cores. We will examine CH3Cl in three different Antarctic ice cores (Taylor Dome, Siple Dome, and West Antarctic Ice Sheet Divide) to investigate links between the in situ CH3Cl production and the impurity content as well as other physical characteristics of ice cores. Measurements are predominantly from the last 10,000 years. Air is extracted from the ice cores using a dry-extraction technique and analyzed with a gas chromatograph coupled to a high-resolution mass spectrometer. The results of this research will establish the likely causes of CH3Cl production in ice cores. This study will provide a basis to assess the viability of studying long-term atmospheric CH3Cl variability using ice core data.
LINKS BETWEEN REGIONAL MONSOON CIRCULATION AND LOCAL HYDRO-CLIMATE IN SOUTHEAST ASIAManuel Hernandez Jr.1, Caroline Ummenhofer2, Kevin Anchukaitis2.
Texas A&M University, College Station, TX, 2Woods Hole Oceanographic Institute, Woods Hole, MA.
1 The Asian summer monsoon, consisting of 3 major subsystems, is characterized by a distinct seasonal precipitation onset that affects the regions of India, the Indochina peninsula, and East Asia. Current monsoon indices for Southeast Asia and the Indian subcontinent capture the large-scale circulation patterns and, in turn, the hydro-climate of the specified area affected by the Asian Monsoon System. However, their skill in representing regional circulation features and links to the local hydro climate are less understood. Here, we assessed the variability within the Dynamical Indian Monsoon Index, the East Asian Western North Pacific Index, and the South Asian Monsoon Index and their links to regional climate features over Southeast Asia, using various observations and reanalysis products at monthly resolution and an extended 1300-yr pre-industrial control run with the Community Earth System Model (CESM).
The monsoon indices in the model compared well with those in the reanalysis, with similar statistical properties.
Furthermore, composites of precipitation, sea surface temperatures (SST), wind fields, and moisture advection during years with an extreme monsoon index (i.e., top and bottom 10%) were explored for the three monsoon indices in the reanalyses and model, respectively. Composites demonstrate large-scale changes in Indo-Pacific SST, circulation, and moisture advection in Southeast Asia, consistent with effects on seasonal precipitation within the region. Our analysis further investigates the paleo climate of Southeast Asia through the CESM control run to identify natural cold SST periods and their effects on circulation and precipitation patterns to understand extended drought periods identified in tree-ring chronologies in Southeast Asia.
DETECTION OF POLYCYCLIC AROMATIC HYDROCARBONS IN ENVIORNMENTAL SEDIMENT SAMPLESAdrian Gomez, Krishna Foster.
California State University, Los Angeles, Los Angeles, CA.
Water is one of the most vital substances on Earth and is the key ingredient for all possible life. As more and more pollution is being released into the atmosphere, the need for clean water is becoming a greater concern for the human population. Polycyclic aromatic hydrocarbons (PAHs) are virtually everywhere and are abundant in sediments, which are directly in contact with life-sustaining surface waters. The objective of this study is to detect PAHs in sediment samples from Ballona and Fern Dell Creeks. These sediment samples were first extracted with the accelerated solvent extractor (ASE) as well as Soxhlet using a hexane and acetone mixture. Then the samples were analyzed using a gas chromatography-mass spectrometer (GC-MS) as well as the high-performance liquid chromatography
(HPLC) equipped with UV-vis and fluorescence detectors. The GC-MS allows the separation of compounds by mass
232 UNDERGRADUATE POSTER ABSTRACTS
to-charge ratios and will be used for identification. The HPLC will be used as a complementary detection technique.
The data obtained will be compared to PAH standards which will allow us to correctly identify if our samples contain these contaminants or not. Water is able to permeate through sediment making this a vital detection analysis because PAHs are all carcinogenic compounds, and so much of creek runoff goes to habitable plant life that this may hyperaccumulate these bioavailable compounds.
DETERMINING THE VERTICAL DISTRIBUTION OF VOLCANIC PLUMES FROM 2004 TO 2013Jonathan Martinez, Steven Massie.
National Center for Atmospheric Research, Boulder, CO.
The goal of this research is to determine the statistics of volcanic injections of sulfur dioxide (SO2) into the atmosphere during 2004 to 2013. We analyzed data from the Smithsonian Global Volcanism Program as well as satellite data from the Ozone Monitoring Instrument (OMI) to obtain a statistical distribution of volcanic plume heights and SO2 column amounts during 2004 to 2013 organized as a function of latitude. Along with this data, a global average of tropopause heights as a function of latitude was used to determine where the volcanic plumes entered the stratosphere. Our analysis indicates that SO2 column amounts increase as the height of the volcanic plume increases for most of the troposphere. The research focuses on small volcanic eruptions during what is known as a quiet time of no large volcanic eruptions. This allows for the determination of the effects and contributions of the smaller volcanic eruptions injecting SO2 into the stratosphere. Once in the stratosphere, the SO2 released by the volcanos oxidizes to form sulfuric acid (H2SO4), which is the key ingredient of sulfate aerosols. These aerosols have been observed to exist in the stratosphere for up to 2 years, and they have impacts on our climate such as cooling the troposphere. This research will help to distinguish the natural volcanic contributions of SO2 in our atmosphere from anthropogenic sources of SO2 such as those due to thermal power plants.
HOW PRE-STORM AND INFLOW REGION DATA COMPARE AND INFLUENCE CONVECTIVE TRANSPORT OF
CHEMICALS TO THE UPPER TROPOSPHEREMeghan Applegate1, Mary Barth2.
Iowa State University, Van Meter, IA, 2National Center for Atmospheric Research, Boulder, CO.
PACIFIC NORTHWEST ECOSYSTEM RESPONSES TO ATMOSPHERIC CHANGES IN THE 21ST CENTURYGabriela De La Cruz Tello1, Gordon Bonan2.
San Jose State University, San Jose, CA, 2National Center for Atmospheric Research, Boulder, CO.
1 The Pacific Northwest is important for various reasons, one of which is its role in the carbon cycle. The carbon cycle regulates carbon pools and fluxes throughout the Earth system. Currently, the Pacific Northwest is a carbon sink;