Physical Sciences and Mathematics Commons^™

The Effect Of Negative-Energy Shells On The Schwarzschild Black Hole, Jeffrey Hazboun, Tevian Dray

Faculty publications

We construct Penrose diagrams for Schwarzschild spacetimes joined by massless shells of matter, in the process correcting minor flaws in the similar diagrams drawn by Dray and ’t Hooft (Commun Math Phys 99:613–625, 1985), and confirming their result that such shells generate a horizon shift. We then consider shells with negative energy density, showing that the horizon shift in this case allows for travel between the heretofore causally separated exterior regions of the Schwarzschild geometry. These drawing techniques are then used to investigate the properties of successive shells, joining multiple Schwarzschild regions. Again, the presence of negative-energy shells leads to …

Failure Detectors For Wireless Sensor-Actuator Systems, Hamza A. Zia, Nigamanth Sridhar, Shivakumar Sastry

Electrical and Computer Engineering Faculty Publications

Wireless sensor-actuator systems (WSAS) offer exciting opportunities for emerging applications by facilitating fine-grained monitoring and control, and dense instrumentation. The large scale of such systems increases the need for such systems to tolerate and cope with failures, in a localized and decentralized manner. We present abstractions for detecting node failures and link failures caused by topology changes in a WSAS. These abstractions were designed and implemented as a set of reusable components in nesC under TinyOS. Results, which demonstrate the performance and viability of the abstractions, based on experiments on an 80 node testbed are presented. In the …

A Sophisticated Library Search Strategy Using Folksonomies And Similarity Matching, William Lund, Yiu-Kai D. Ng, Maria Soledad Pera

Faculty Publications

Libraries, private and public, offer valuable resources to library patrons. As of today the only way to locate information archived exclusively in libraries is through their catalogs. Library patrons, however, often find it difficult to formulate a proper query, which requires using specific keywords assigned to different fields of desired library catalog records, to obtain relevant results. These improperly formulated queries often yield irrelevant results or no results at all. This negative experience in dealing with existing library systems turn library patrons away from library catalogs; instead, they rely on Web search engines to perform their searches first and upon …

Fan Cohomology And Its Application To Equivariant K-Theory Of Toric Varieties, Suanne Au

Department of Mathematics: Dissertations, Theses, and Student Research

Mu-Wan Huang, Mark Walker and I established an explicit formula for the equivariant K-groups of affine toric varieties. We also recovered a result due to Vezzosi and Vistoli, which expresses the equivariant K-groups of a smooth toric variety in terms of the K-groups of its maximal open affine toric subvarieties. This dissertation investigates the situation when the toric variety X is neither affine nor smooth. In many cases, we compute the Čech cohomology groups of the presheaf K_q^T on X endowed with a topology. Using these calculations and Walker's Localization Theorem for equivariant K-theory, we give explicit formulas …

Modeling And Analysis Of Biological Populations, Joan Lubben

Department of Mathematics: Dissertations, Theses, and Student Research

Asymptotic and transient dynamics are both important when considering the future population trajectory of a species. Asymptotic dynamics are often used to determine whether the long-term trend results in a stable, declining or increasing population and even provide possible directions for management actions. Transient dynamics are important for estimating invasion speed of non-indigenous species, population establishment after releasing biocontrol agents, or population management after a disturbance like fire. We briefly describe here the results in this thesis.

(1) We consider asymptotic dynamics using discrete time linear population models of the form n(t + 1) = An(t) where …

Mathematical Beauty And Its Characteristics- A Study On The Student's Point Of View, Astrid Brinkmann

The Mathematics Enthusiast

Based on the statement, that the experience of mathematical beauty has a positive influence on students’ motivations and attitudes towards mathematics and its study, the focus of this paper is the aesthetic component of mathematics. First, the role of aesthetics for perception and education is addressed. The appreciation of the beauty of mathematics is one of the wellsprings of this subject, not only in research but also in school education. This should have implications for the teaching of mathematics. However the beauty making elements have not been very well analysed. In particular, it is not clear to what extent the …

The Contributions Of Comprehension Tests To Cognitive And Affective Development Of Prospective Teachers: A Case Study, Yüksel Dede

The Mathematics Enthusiast

The aim of this study was to investigate the role of comprehension tests while teaching algebra and its effects on students’ success. This study was carried out with 108 third year undergraduate students enrolled in math education in faculty of education. Several data collection instruments were used for gathering data from the participants such as; comprehension test, written documents, semi-structured interviews schedule, and participant and nonparticipant observations sheets. Collected data were subjected to content analysis and triangulation among the data was ensured. Results indicated that three different major categories emerged from the content analysis of the data: (1) measure of …

Cubism And The Fourth Dimension, Elijah Bodish

The Mathematics Enthusiast

When one looks into the subject of geometries that attempt to explain fourthdimensional space, it is inevitable that one encounters references to Cubism. The purpose of this paper is to find what the similarities between this mathematical concept and cubism are. There are many historical arguments as to how the cubists encountered literature about the fourth-dimension, and whether they were exposed to it at all, which I will for the most part omit and instead let the art speak for itself. It is important to see how two fields are interrelated in order to gain a better understanding of both …

If Mathematics Is A Language, How Do You Swear In It?, Dave Wagner

The Mathematics Enthusiast

Swears are words that are considered rude or offensive. Like most other words, they are arbitrary symbols that index meaning: there is nothing inherently wrong with the letters that spell a swear word, but strung together they conjure strong meaning. This reminds us that language has power. This is true in mathematics classrooms too, where language practices structure the way participants understand mathematics and where teachers and students can use language powerfully to shape their own mathematical experience and the experiences of others.

From Trapezoids To The Fundamental Theorem Of Calculus, William Gratzer, Srilal Krishnan

The Mathematics Enthusiast

The philosophy of Mathematics Education undergoes changes from the school to college level and students generally have a tough time coping with the transition. It is our endeavor to impress the importance of introducing college level topics at an early stage, so that students are not lost in the transition. Keeping this in mind, we suggest an early exposure to an important topic from Calculus; approximating the area of a planar region. Traditionally this topic is introduced using Riemann Sums but in this paper we try to follow a student’s natural inclination in approximating areas and explain how this approach …

Sum Of "N" Consecutive Integers, Steve Humble

The Mathematics Enthusiast

For all n , it is always possible to find at least one sum of n consecutive numbers with an equivalent sum of n - 1 consecutive numbers?

On The Use Of Realistic Fermi Problems For Introducing Mathematical Modelling In School, Jonas Bergman Ärlebäck

The Mathematics Enthusiast

In this paper uses an analytical tool refereed to as the MAD (Modelling Activity Diagram) framework adapted from Schoenfeld’s parsing protocol coding scheme to address the issues of how to introduce mathematical modelling to upper secondary students. The work of three groups of students engaged in solving so called realistic Fermi problems were analysed using this framework, and it was observed that the processes involved in a typical mathematical modelling cycle were richly represented in the groups’ solving processes. The importance of the social interactions within the groups was noted, as well as the extensive use of extramathematical knowledge used …

Little Venice Water Quality Monitoring Project: Epa Assistance Agreement X7-96410604-3 And Fdep Contract Sp674 & Sp678, Joseph N. Boyer, Henry O. Briceño

SERC Research Reports

No abstract provided.

Cooper's Green World: Adapting Ecosemiotics To The Mythic Eastern Woodlands, Paul Siewers

Faculty Contributions to Books

James Fenimore Cooper's Leatherstocking Tales situated in a Trans-Atlantic Green World tradition of Anglophone literature, related also to Native American culture.

Iowa Academy Of Science: The New Bulletin, V05n2, Summer 2009, Iowa Academy Of Science

New Bulletin

Inside This Issue:

--Message from the Executive Director

--IJAS Students Speak with NASA Scientists

--Geological Society of Iowa Field Trips

--Announcements, Events & Deadlines

--2009 IJAS Annual Meeting Winners

--2009 IAS Speaker Series at the Saylorville Visitor Center

--Remembering Dr. Thomas Huston Macbride

--Iowa Science Teaching Section Fall Conference

--Project WET

String Resonances At The Large Hadron Collider, Arunava Roy, Marco Cavaglia

Physics Faculty Research & Creative Works

The Large Hadron Collider promises to discover new physics beyond the standard model. An exciting possibility is the formation of string resonances at the TeV scale. In this article, we show how string resonances may be detected at the LHC in the pp →γ + jet channel. Our study is based on event-shape variables, missing energy and momentum, maximum transverse momentum of photons and dijet invariant mass. These observables provide interesting signatures which enable us to discriminate string events from the standard model background.

Accurate Retrieval Of Atomic Structures From High-Order Harmonic Spectra, Toshihito Umegaki, Toru Morishita, Shinichiro Minemoto, Yuichiro Oguchi, Anh-Thu Le, Shinichi Watanabe, Hirofumi Sakai

Physics Faculty Research & Creative Works

We extracted the photorecombination cross sections from the high-order harmonic spectra generated from rare gases by intense femtosecond pulses. By taking the ratio between the observed high-order harmonic spectra and recolliding electron wave packets, we successfully obtained the photorecombination cross sections.

Invasive Species Management Plan For Oswego Lake, Daniel Warren, Mark Sytsma

Environmental Science and Management Professional Master's Project Reports

This Invasive Species Management Plan defines an overarching strategy for the Lake Oswego Corporation (LOC) to mitigate threats from invasive species to Oswego Lake. Invasive species pose a direct risk to recreational and aesthetic uses of the lake, critical LOC infrastructure, and ecological communities within the lake. The Plan is particularly concerned with two bivalve mollusks in the genus Dreissena: the zebra mussel (Dreissena polymorpha) and the quagga mussel (Dreissena bugensis). These mussels grow in dense colonies that damage watercraft and underwater structures as well as displace native species. A recent scientific report found that …

Water Quality Sampling, Analysis And Annual Load Determinations For The Illinois River At Arkansas Highway 59 Bridge, 2008, L.B. Massey, L.W. Cash, B.E. Haggard

Technical Reports

The Arkansas Water Resources Center monitored water quality at the Illinois River at the Arkansas Highway 59 Bridge, just upstream from the Arkansas-Oklahoma state border during base flow and storm events from July 1, 2008 through June 30, 2009. Water samples were collected manually or with an auto-sampler and analyzed for nitrate-nitrogen, ammonia-nitrogen, total nitrogen, total phosphorus, soluble reactive phosphorus, sulfate, chloride and total suspended solids. The U.S. Geological Survey recorded instantaneous stage and discharge at the site, total annual discharge was 1,010,000,000 m³ , with 37% attributed to base flow and 63% attributed to storm flow. Loads were estimated …

Water Quality Sampling, Analysis And Annual Load Determinations For Nutrients And Solids On The Ballard Creek, 2008, L.B. Massey, L.W. Cash, B.E. Haggard

Technical Reports

The Arkansas Water Resources Center monitored water quality at Ballard Creek at the Washington County Road 76 Bridge in northwest Arkansas during base flow and storm events from July 1, 2008 through June 30, 2009. Water samples were collected manually or with an auto-sampler and analyzed for nitrate-nitrogen, ammonia-nitrogen, total nitrogen, total phosphorus, soluble reactive phosphorus, sulfate, chloride and total suspended solids. Instantaneous stage and discharge were recorded at the site; total annual discharge was 55,800,000 m³ , with 27% attributed to base flow and 73% attributed to storm flow. Loads were estimated using the mid-interval integration approach using continuous …

Illinois River Volunteer Monitoring, L.B. Massey, B.E. Haggard

Technical Reports

Understanding how water quality conditions change along a land use gradient and over time is important for sustainable watershed management. Therefore, a volunteer monitoring program was created to measure water chemistry at 37 established sites within the Upper Illinois River Watershed and to evaluate changes in water chemistry over the past 15 years. The Illinois River Watershed Partnership (IRWP), a non‐profit organization subcontracted with the Arkansas Water Resources Center at the University of Arkansas, to manage the volunteer monitoring project, train volunteers to collect samples following EPA approved methods, and to analyze the collected samples. The AWRC trained 27 volunteers …

Heterosternuta Sulphuria (Coloptera: Dytiscidae) Occurence In The Sulphur Springs Headwater System And In Buffalo National River Tributaries (Arkansas, Usa): Current Distribution, Habitat Conditions, And Biomonitoring Framework, S.D. Longing, B.E. Haggard

Technical Reports

Heterosternuta sulphuria is an endemic aquatic species of concern in Arkansas, with a priority score of 80 out of 100 and a conservation rank of S1and G1. A need of the Arkansas Wildlife Action Plan (AWAP) was to obtain baseline information on distribution and population status of H. sulphuria. Here, we report new H. sulphuria records for 39 sites across 10 counties in the Ozark Highlands and Boston Mountain ecoregions and a determined habitat type of shallow margins and small bedrock pools of perennial streams and spring seeps. Few habitat patches were observed per site because detection was typically rapid …

Frequency Distributions Of Median Nutrient And Chlorophyll Concentrations Across The Red River Basin, 1996-2006, S.D. Longing, B.E. Haggard

Technical Reports

Acquisition and compilation of water quality data for a ten year time period (1996 – 2006) from 589 stream and river stations was conducted to support nutrient criteria development for the multi–state Red River Basin shared by Arkansas, Louisiana, New Mexico, Oklahoma and Texas, USA. Twenty–three water quality parameters were collected from five data sources (USGS, ADEQ, LDEQ, OCC, OWRB, and TCEQ) and an additional 13 parameters were acquired from at least one source. Data for the primary biological parameter of interest, chlorophyll a, was sparse and available from only two sources. Following compilation of data, medians were calculated for …

Excess Of Glucocorticoid Induces Cardiac Dysfunction Via Activating Angiotensin Ii Pathway, Sreerupa Ghose Roy, Priyanka De, Debasri Mukherjee, Vivek Chander, Aditya Konar, Debasish Bandyopadhyay, Arun Bandyopadhyay

Chemistry Faculty Publications and Presentations

Background: Glucocorticoid is widely used as an anti-inflammatory drug in various diseases however excess of it often causes cardiovascular complications. The present study was undertaken to understand the molecular mechanism of glucocorticoid-induced cardiac dysfunction.

Methods: Rats were treated daily with synthetic glucocorticoid, dexamethasone with or without mifepristone or losartan up to 15 days. Hemodynamic parameters were measured by PV-loop method using Millar's instrument. Cardiac remodelling, fibrosis and oxidative stress were monitored after 15 days.

Results: The systolic blood pressure was increased whereas the heart beat and cardiac output (n=6) were decreased by dexamethasone. Dexamethasone caused increase in the heart …

Reactivity And Chemical Characterization Of Dissolved Organic Matter In An Estuary, Hussain A. Abdulla

OES Theses and Dissertations

This dissertation used Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (¹³C-NMR) data to quantify the changes of major chemical compound classes in high molecular weight (HMW, >1kDa) DOM isolated along a transect from Great Dismal Swamp through the Elizabeth River/Chesapeake Bay system to the coastal Atlantic Ocean off Virginia, USA. Results show that both carboxylic acids and aromatic compounds are lost along the transect, while amide, and carbohydrate moieties could have a mid-transect source.

Addressing the seasonal and spatial changes in the chemical composition of high molecular weight DOM using C/N ratio and δ^{13 …}

A Simulation Study Of Convergence Speed For Distributed Codeword Adaptation Algorithms In Cdma Wireless Systems, Sahana Maharjan

Electrical & Computer Engineering Theses & Dissertations

In this thesis we present a side-by-side comparison of interference avoidance (IA) algorithms for distributed codeword adaptation in Code Division Multiple Access (CDMA) systems. In CDMA systems, the interference is determined by the values of the cross-correlation of codewords assigned to users, and various algorithms can be used for codeword optimization. The IA algorithms for codeword adaptation considered are the eigen-algorithm, the Minimum Mean Square Error (MMSE) update, and the adaptive IA algorithm, for which we investigate convergence speed using the extensive simulations of several uplink CDMA system scenarios. The results of this thesis were presented at the Fourth IEEE …

Virtual Wired Transmission Scheme - A Novel Technique For Efficient Mobile Adhoc Networks, Manikya Vinay Rali

Electrical & Computer Engineering Theses & Dissertations

This thesis proposes a method called virtual wired transmission scheme for ad hoc networks. The scheme is an efficient method to improve network performance parameters such as energy efficiency, capacity, interference, network throughput, etc. Performance parameters improvement can be done at different layers of the network architecture for mobile ad hoc networks. However most of the research efforts are concentrated on Physical, MAC and Network layers. In this thesis, a MAC protocol with a major MAC layer modification is proposed in combination with the usage of directional antennas, developing a novel method called virtual wired transmission scheme. In virtual wired …

Changing Fecundity And Reproductive Output In Females Of A Chesapeake Bay Population Of Blue Crab, Callinectes Sapidus, Shannon L. Wells

OES Theses and Dissertations

The Chesapeake Bay blue crab, Callinectes sapidus, is an important species both ecologically and as a fishery. Fishery dependent and independent data indicate that the population declined abruptly in the mid-1990s and has remained low. Previous work prior to the decline in population abundance found a significant relationship between size and fecundity for mature females. As with many heavily fished populations, this population has experienced a reduction in the size at maturity. The objectives of this study were to reassess the fecundity of the population, determine the lipid and protein energy allocated for reproduction, and to examine the concentrations …

The Use Of Fourier Transform (Ft) Surface-Enhanced Raman Scattering For Biochemical Analysis, Robert Butler Jeffers

Chemistry & Biochemistry Theses & Dissertations

Surface-enhanced Raman scattering (SERS) is a powerful spectroscopic technique that has created exciting opportunities in the field of bioanalytical chemistry, where it combines ultrasensitive detection of biologically relevant molecules with vibrational spectroscopy. Due to the difficulties in preparing reproducible SERS active substrates, SERS has been mainly used as a qualitative tool. In order for SERS to be utilized as a viable tool for quantitative analysis, simple, facile SERS substrates which generate clean, highly reproducible signals must be developed. This dissertation deals with the evaluation of three different methods of SERS that led to the development of a novel substrate for …

An Adaptive Method For Calculating Blow-Up Solutions, Charles F. Touron

Mathematics & Statistics Theses & Dissertations

Reactive-diffusive systems modeling physical phenomena in certain situations develop a singularity at a finite value of the independent variable referred to as "blow-up." The attempt to find the blow-up time analytically is most often impossible, thus requiring a numerical determination of the value. The numerical methods often use a priori knowledge of the blow-up solution such as monotonicity or self-similarity. For equations where such a priori knowledge is unavailable, ad hoc methods were constructed. The object of this research is to develop a simple and consistent approach to find numerically the blow-up solution without having a priori knowledge or resorting …