Digital Commons Network^™

Warnings Of An “Insect Apocalypse” Are Premature, Timothy D. Schowalter, Michael R. Willig, Stephen J. Presley, Manoj Pandey

Faculty Publications

No abstract provided.

Effect Of Two Digestive Enzymes And Ph On The Dsrna Of Endornaviruses Of Bell Pepper And Melon Under In Vitro Conditions, Adair Mccanless, Allison Hultgren, Cesar Escalante, Alyssa Ardt, Rodrigo A. Valverde

Faculty Publications

Purpose: The objective of this investigation was to determine the in vitro effect of two common digestive enzymes, amylase and pepsin, and pH on the integrity of the RI dsRNA of bell pepper endornavirus (BPEV) and Cucumis melo endornavirus (CmEV) evaluated by gel electrophoresis and reverse-transcription PCR (RT-PCR). Methods: We conducted experiments on the in vitro effect of two common digestive enzymes, amylase and pepsin, and pH on the structural integrity of the replicative intermediate (RI) dsRNA of bell pepper endornavirus (BPEV) and Cucumis melo endornavirus (CmEV), evaluated by gel electrophoresis and reverse-transcription polymerase chain reaction. Result: The effect of …

Fertilizer Source And Irrigation Depth A¡Ect Nutrient Leaching During Coleus Container Production, Kayla R. Sanders, Jeffrey S. Beasley, Edward W. Bush, Stacia L. Conger

Faculty Publications

Nutrient leaching during nursery container production can have negative effects on plant growth and the environment. The objective of this study was to evaluate effects of fertilizer source at two irrigation depths on nutrient leaching during coleus [Plectranthus scutellarioides (L.) Codd] ‘Solar Sunrise’ container production to develop best management practices. Coleus received no fertilizer, a controlled-release fertilizer (CRF), or a water-soluble fertilizer (WSF) applied at 0.30 kg N and P per m3 (0.02 lb per ft3) and were irrigated at 1.9 or 3.8 cm.day1 (0.7 or 1.5 in.day1) for 56 days after planting (DAP). Leachate was analyzed every 7 DAP …

Survival And Inactivation Of Salmonella Enterica Serovar Typhimurium On Food Contact Surfaces During Log, Stationary And Long-Term Stationary Phases, Dorra Djebbi-Simmons, Wenqing Xu, Marlene Janes, Joan King

Faculty Publications

One of the most important transmission routes of foodborne pathogens is through contaminated food contact surfaces. In this study, we investigated the survival and inactivation of Salmonella enterica serovar Typhimurium on frequently used food contact surfaces in household settings, including plastic cutting board (CB), formica laminate (LA), and stainless steel (SS) surfaces. S. Typhimurium at log (6 h), stationary (24 h), or long-term stationary (LTS) (14 days) phases were evaluated. Results showed that, at medium and high microbial loads, LTS phase cells had significantly higher survivor population compared to log and stationary phase cells at 24 h after inoculation (p < 0.05). Disinfection study showed that LTS phase cells were very resilient to sodium hypochlorite when the initial microbial load was high with disinfection efficacy ranging from 26 to 35%. Scanning electron microscopy of these surfaces at 24 h after inoculation with a high microbial load revealed an early biofilm structure.

In-Line Spectral Interferometry In Shortwave-Infrared Laser Filaments In Air, Xiaoming Ren, Yang Wang, Zenghu Chang, James Welch, Aaron Bernstein, Michael Downer, Jeffrey Brown, Mette Gaarde, Arnaud Couairon, Miroslav Kolesik, Pavel Polynkin

Faculty Publications

We investigate the nonlinear propagation of intense, two-cycle, carrier-envelope phase (CEP) stable laser pulses at 1.7  μm center wavelength in air. We observe CEP-dependent spectral interference in the visible part of the forward-propagating white light generated on propagation. The effect is robust against large fluctuations of the input pulse energy. This robustness is enabled by rigid clamping of both the peak optical field and the phase of the propagating waveform, which has been revealed by numerical simulations. The CEP locking can enhance the yield of the CEP-dependent strong-field processes in gaseous media with long-wavelength drivers, while the observed spectral interference …

Measurement Of The Energy Spectra And Of The Angular Distribution Of The Transition Radiation With A Silicon Strip Detector, F. Loparco, J. Alozy, N. Belyaev, M. Campbell, M. Cherry, F. Dachs, S. Doronin, K. Filippov, P. Fusco, F. Gargano, E. Heijne, S. Konovalov, D. Krasnopevtsev, X. Llopart, V. Mascagna, M. N. Mazziotta, H. Pernegger, D. Ponomarenko, M. Prest, D. Pyatiizbyantseva, R. Radomskii, C. Rembser, A. Romaniouk, A. A. Savchenko, D. Schaefer, E. J. Schioppa, D. Shchukin, D. Yu Sergeeva, E. Shulga, S. Smirnov, Y. Smirnov, M. Soldani, P. Spinelli

Faculty Publications

We plan to develop an advanced Transition Radiation Detector (TRD) for hadron identification in the TeV momentum range, based on the simultaneous measurement of the energies and of the emission angles of the Transition Radiation (TR) X-rays with respect to the radiating particles. To study the feasibility of this project, we have carried out a beam test campaign at the CERN SPS facility with 20 GeV/c electrons and muons up to 300 GeV/c. To detect the TR X-rays and the radiating particles, we used a 300 μm thick double-sided silicon strip detector, with a strip readout pitch of 50 μm. …

Amphiphilic Polypeptoids Rupture Vesicle Bilayers To Form Peptoid-Lipid Fragments Effective In Enhancing Hydrophobic Drug Delivery, Yueheng Zhang, Zahra Heidari, Yang Su, Tianyi Yu, Sunting Xuan, Marzhana Omarova, Yucel Aydin, Srikanta Dash, Donghui Zhang, Vijay John

Faculty Publications

Copyright © 2019 American Chemical Society. Peptoids are highly biocompatible pseudopeptidic polyglycines with designable substituents on the nitrogen atoms. The therapeutic and drug-carrying potential of these materials requires a fundamental understanding of their interactions with lipid bilayers. In this work, we use amphiphilic polypeptoids with up to 100 monomeric units where a significant fraction (26%) of the nitrogen atoms are functionalized with decyl groups (hydrophobes) that insert into the lipid bilayer through the hydrophobic effect. These hydrophobically modified polypeptoids (HMPs) insert their hydrophobes into lipid bilayers creating instabilities that lead to the rupture of vesicles. At low HMP concentrations, such …

@Houstonpolice: An Exploratory Case Of Twitter During Hurricane Harvey, Seungwon Yang, Brenton Stewart

Faculty Publications

Abstract

Purpose

The purpose of this paper is to examine the Houston Police Department (HPD)’s public engagement efforts using Twitter during Hurricane Harvey, which was a large-scale urban crisis event.

Design/methodology/approach

This study harvested a corpus of over 13,000 tweets using Twitter’s streaming API, across three phases of the Hurricane Harvey event: preparedness, response and recovery. Both text and social network analysis (SNA) techniques were employed including word clouds, n-gram analysis and eigenvector centrality to analyze data.

Findings

Findings indicate that departmental tweets coalesced around topics of protocol, reassurance and community resilience. Twitter accounts of governmental agencies, such as …

The Societal Collapse Of The Southern Lowland Maya Civilization: Don’T Miss The Forest For The Trees, Dwayne Hinton

Honors Capstones

No abstract provided.

Modeling And Simulations Of Peptoids, Pu Du

LSU Doctoral Dissertations

Polypeptoids, or poly-N-substituted glycines, are a class of sequence defined polymers that are structural mimics of polypeptides. Polypeptoids currently have received a growing interest due to their improved thermal stability, larger chemical diversity, and easier synthetic pathways as compared to peptides. Their lack of backbone hydrogen bonding and stereochemistry coupled with their easily tunability make them an ideal prototypical model system to study the effect of secondary/non-covalent interactions on self-assembly in solution. In order to develop a molecular level understanding of the effect of secondary interactions on polypeptoid self-assembly, systematic studies were carried out using molecular dynamics simulations on several …

Race, Geography, And News Coverage Of The Opioid Epidemic, Nicholas B. Robert

LSU Master's Theses

The opioid epidemic is the deadliest drug epidemic in United States history. During the early stages of the epidemic, the focus was on white victims in rural and suburban areas. Using the geo-ethnic framework developed from immigration research, this study examines if geography and race impacted the framing of the opioid epidemic in newspapers. The study finds there to be a low level of geo-ethnic influenced framing in news coverage of the opioid epidemic from 2016-2018.

Supporting The Algebra I Curriculum With An Introduction To Computational Thinking Course, Michelle M. Laskowski

LSU Master's Theses

The Louisiana Workforce Commission predicts a 33.6% increase in computer science and mathematical occupations by 2022 and the Bureau of Labor Statistics foresees a 16% increase in computer scientists from 2018-2028. Despite these opportunities for job and financial security, the number of Louisiana students enrolled in a nationally accredited computing course is less than 1%, compared to national leaders California and Texas which have 3% and 3.8% of students respectively. Furthermore, the international assessments of mathematical literacy, PISA and TIMMS, both report American students continue to fall further behind their international peers in mathematics achievement.

This thesis rejects these statistics …

Effective Fuzzing Framework For The Sleuthkit Tools, Shravya Paruchuri

LSU Master's Theses

The fields of digital forensics and incident response have seen significant growth over the last decade due to the increasing threats faced by organizations and the continued reliance on digital platforms and devices by criminals. In the past, digital investigations were performed manually by expert investigators, but this approach has become no longer viable given the amount of data that must be processed compared to the relatively small number of trained investigators. These resource constraints have led to the development and reliance on automated processing and analysis systems for digital evidence. In this paper, we present our effort to develop …

Hierarchical Conjugated Polymer Systems Prepared By Controlled Chain-Growth Polymerization, Chunwa Peter Kei

LSU Doctoral Dissertations

π-Conjugated polymer materials may have a significant economic impact on society by providing means for designing affordable, flexible, and portable organic electronic devices. Their successful commercialization will depend on major scientific advancements, which will challenge human society to seek out ever more detailed and fundamental processes to command. Controlled polymerization affords such a power; allowing for the design of meticulous and precisely defined systems granting detailed insight into structure-property relationships in the polymer materials and bettering understanding of novel physical phenomena.

This dissertation primarily focuses on development and preparation of well-defined hierarchically organized macromolecular systems. The novel chain-growth polymerization methodologies …

Mini-Actors, Mega-Stages: Examining The Use Of Theatre Among Children And Youth In U.S. Evangelical Megachurches, Carla Elisha Lahey

LSU Doctoral Dissertations

How do children and youth first encounter the performing arts? While schools may stand out as an obvious answer, a recent study conducted by the U.S. Department of Education shows that the percentage of public schools offering theatre classes dropped at both the primary and secondary level from 2000-2010 (Brenchley). Yet, even as arts offerings experience a decline in some public schools, many students are being introduced to performance through another venue – the evangelical megachurch.

Since the birth of the church growth movement in the 1970s, megachurches (defined as Protestant congregations that average at least 2,000 weekly attendees) have …

Social Justice Through Social Media: The Use Of Twitter As A Tool For Activism In The #Metoo #Blacklivesmatter Era, Laura L. Coleman

LSU Master's Theses

This study focuses on social justice and how people on Twitter chose to talk about it. The rise of social media has allowed Twitter users to speak more freely in more spaces than one. The study compared two different sexual assault cases between Judge Brett Kavanaugh and Professor Christine Blasey; and Virginia’s Lt. Governor Justin Fairfax and Vanessa Tyson. Applying the social responsibility theory, which allows free press without any censorship, I then can see the tone of which Black Twitter users have when talking about two separate sexual assault cases. This study compares the use of the #BlackTwitter hashtag …

The Use Of Social Media In Emergency Management By Public Agencies And Non-Governmental Organizations: Lessons Learned From Areas Affected By Hurricanes Isaac, Sandy, And Harvey, Ryan Hamilton Kirby

LSU Doctoral Dissertations

Natural disasters are increasingly costly for the United States. The literature suggests emergency managers may improve disaster outcomes and enhance disaster resilience by supplementing their official public-communications methods with more bi-directional communication tactics using social media. This study aims to understand how social media is used within the “whole community” of emergency management in areas affected by recent hurricanes. The first research objective examines how social media is used by governmental and non-governmental organizations across the four phases of emergency management (preparedness, response, recovery, mitigation). The second objective is to identify challenges governmental and non-governmental groups have encountered and strategies …

Bio-Mechanical Characterization Of Adherent Cell Layers With A Pdms Cantilever, Merrel Truly Holley

LSU Doctoral Dissertations

In the last few decades, the mechanical characteristics of human cells has been linked to many physiological processes and pathological conditions, illustrating the importance as effective biomarkers. Mounting research has shown the mechanical force between cells and the extracellular matrix (ECM) plays a vital role in cellular processes such as tissue homeostasis, wound healing, cancer metastasis, and the progression of various diseases. This mechanical force, or the force that a cell produces on its surroundings, is termed as the cellular traction force (CTF). Precise characterization of the CTF can expand our knowledge of these important cellular processes as well as …

Transgenic Control Of Aflatoxin Contamination In Maize Through Host-Induced Gene Silencing Targeting Aspergillus Flavus Genes Encoding Polygalacturonase (P2c) And Versicolorin Dehydrogenase (Aflm), Yenjit Raruang

LSU Doctoral Dissertations

Maize (Zea mays L.) is susceptible to Aspergillus flavus infection and subsequent contamination with aflatoxins, the most potent naturally produced carcinogenic secondary metabolites. Here, the A. flavus gene aflM encoding the versicolorin dehydrogenase in aflatoxin biosynthesis and the p2c gene encoding the polygalacturonase that is involved in infection were selected as targets for suppression through host induced gene silencing (HIGS). A HIGS vector targeting these genes was constructed and introduced into immature B104 maize embryos. Thirteen out of fifteen p2c transformation events and six out of seven aflM events were confirmed positive by PCR. Kernels containing the p2c gene …

Effect Of Storage Temperature On The Survival Or Growth Of Listeria Monocytogenes On Whole And Fresh-Cut Produce, Juan F. Moreira Calix

LSU Master's Theses

Whole and fresh-cut produce are minimally processed and, therefore susceptible to microbial contamination. This study examined the survival or growth of Listeria monocytogenes on whole, and fresh-cut produce at different storage temperatures. Fresh fruits (cantaloupes, pears, pineapples, papayas, and watermelon) and vegetables (broccoli, cauliflower, lettuce, kale, and green bell peppers) were cut into 25 g pieces and were spot inoculated with 0.5 mL (8 Log CFU/mL) of Listeria monocytogenes. Inoculated fresh-cut samples were stored at 4°C or 13°C for 6 days. To represent the outer surface of the produce, cantaloupes and green bell pepper disks (20 cm2) were cut with …

Habitat Associations And Reproduction Of Fishes On The Northwestern Gulf Of Mexico Shelf Edge, Elizabeth Marie Keller

LSU Doctoral Dissertations

Several of the northwestern Gulf of Mexico (GOM) shelf-edge banks provide critical hard bottom habitat for coral and fish communities, supporting a wide diversity of ecologically and economically important species. These sites may be fish aggregation and spawning sites and provide important habitat for fish growth and reproduction. Already designated as habitat areas of particular concern, many of these banks are also under consideration for inclusion in the expansion of the Flower Garden Banks National Marine Sanctuary. This project aimed to gain a more comprehensive understanding of the communities and fish species on shelf-edge banks by way of gonad histology, …

Andrew T. Hatcher: Press, Public Information & Perception For A Nation In Transition Historical Content Analysis On The First African American To Serve As A White House Associate Press Secretary, Nayita Wilson

LSU Master's Theses

Andrew T. Hatcher rose to one of the highest positions in U.S. government when he became the first African American to serve as associate White House press secretary in 1960 under the administration of President John F. Kennedy and during the peak of the Civil Rights Movement. This is a historical content analysis that analyzes Hatcher’s role through primary sources, presidential archives, and select national, local, and minority newspapers.

The overarching purpose of this study was to ascertain Hatcher’s role as associate White House press secretary during civil rights. This study provides further insight into: 1) to what extent did …

A Deda Family Membrane Protein Is Required For Burkholderia Thailandensis Colistin Resistance, Pradip R. Panta, Sujeet Kumar, Caroline F. Stafford, Caitlin E. Billiot, Martin V. Douglass, Carmen M. Herrera, M. Stephen Trent, William T. Doerrler

Faculty Publications

© Copyright © 2019 Panta, Kumar, Stafford, Billiot, Douglass, Herrera, Trent and Doerrler. Colistin is a “last resort” antibiotic for treatment of infections caused by some multidrug resistant Gram-negative bacterial pathogens. Resistance to colistin varies between bacterial species. Some Gram-negative bacteria such as Burkholderia spp. are intrinsically resistant to very high levels of colistin with minimal inhibitory concentrations (MIC) often above 0.5 mg/ml. We have previously shown DedA family proteins YqjA and YghB are conserved membrane transporters required for alkaline tolerance and resistance to several classes of dyes and antibiotics in Escherichia coli. Here, we show that a DedA family …

Organophilic, Superparamagnetic, And Reversibly Thermoresponsive Silica-Polypeptide Core-Shell Particles, Sibel Turksen-Selcuk, Cornelia Rosu, Alyssa Blake, Erick Soto-Cantu, Jianhong Qiu, Yan Wu, J. F. Ditusa, Amanda Steffens, Paul S. Russo

Faculty Publications

Particles with a superparamagnetic cobalt inner core, silica outer core, and covalently bound homopolypeptide shell were investigated under thermal and magnetic stimuli. The homopolypeptide was poly(ϵ-carbobenzyloxy-l-lysine), PCBL, which is known to exhibit a thermoreversible coil → helix transition when dissolved as a pure polymer in m-cresol. Tethering to a core particle did not prevent PCBL from undergoing this conformational transition, as confirmed by dynamic light scattering and optical rotation, but the transition was broadened compared to that of the untethered polymer. The Co@SiO2-PCBL hybrid particles retained the superparamagnetic properties of the cobalt inner nougat. Indeed, some response remains even after …

The Impact Of Experimentally-Induced Perceived Discrimination On Substance Use, Kimberlye Elise Dean

LSU Doctoral Dissertations

Substance use disorders (SUDs) are among the most debilitating psychiatric disorders. Although prevalence rates of SUDs are similar between White and Black adults, these groups experience differential treatment outcomes (e.g., Black adults with SUDs are more likely to report greater pre- and post-treatment substance use). Examining culture-specific correlates of racial differences in substance use is vital to improve understanding of the etiological and maintaining mechanisms of SUDs among Black adults. Perceived racial discrimination (PRD) is prospectively related to various substance use-related outcomes. Thus, some may use substances to alleviate psychological distress (e.g., anxiety) associated with PRD, which may over time …

Ruddlesden–Popper Perovskites: Synthesis And Optical Properties For Optoelectronic Applications, Xupeng Gao, Xiangtong Zhang, Wenxu Yin, Hua Wang, Yue Hu, Qingbo Zhang, Zhifeng Shi, Vicki L. Colvin, William W. Yu, Yu Zhang

Faculty Publications

© 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Ruddlesden–Popper perovskites with a formula of (A′)2(A)n−1BnX3n+1 have recently gained widespread interest as candidates for the next generation of optoelectronic devices. The variations of organic cation, metal halide, and the number of layers in the structure lead to the change of crystal structures and properties for different optoelectronic applications. Herein, the different synthetic methods for 2D perovskite crystals and thin films are summarized and compared. The optoelectronic properties and the charge transfer process in the devices are also delved, in particular, for light-emitting diodes and solar cells.

The Power Of Wording: An Evaluation Of Framing Effects, Chelsea Romph

Honors Capstones

No abstract provided.

The Ability Of Β-Hairpin Peptides To Function As Degradation-Resistant, Cell-Penetrating Peptides And Their Potential As Proteolysis Targeted Chimeras, Jeffery C. Anderson

Honors Capstones

No abstract provided.

Review Of Naturally Occurring Ammonia In Groundwater And Its Effect On Using Chloramines For Drinking Water Disinfection In Louisiana, Athena Lindsay

Honors Capstones

No abstract provided.

Prevalence And Control Of Salmonella Spp. And Sanitary Indicator Microorganisms In Wild Caught And Farm Raised Catfish (Ictalurus Punctatus), Bilan Costley Jessie

LSU Doctoral Dissertations

Catfish inspections have transitioned from the U.S. Food and Drug Administration (FDA) to the United States Department of Agriculture (USDA). The USDA Food Safety and Inspection Service (FSIS) and Food Emergency Response Network (FERN) consider it important to assess the food safety risk associated with consuming catfish in the United States. Surveillance of farm-raised and wild-caught catfish for pathogens is relevant as a public safety protocol. The purpose of this study was to detect the prevalence of Salmonella spp., identify and examine isolates for antibiotic resistance to clinical treatments, evaluate the effectiveness of antimicrobial chemical treatments against Salmonella enterica, and …