- Toxicological Case Study of Dallas' Central Wastewater Treatment Plant Effluent and Ambient Trinity River Samples: 1989, 1990, 1991
- "This study was implemented voluntarily by personnel at Dallas Water Utilities in response to concerns that the Dallas Central Wastewater Treatment Plant was adversely affecting downstream water quality." The treatment plant was studied to determine whether it was "discharging toxic materials in toxic amounts to the Trinity River" (p. 1). digital.library.unt.edu/ark:/67531/metadc29402/
- Remote Sensing and GIS for Nonpoint Source Pollution Analysis in the City of Dallas' Eastern Watersheds
- This report describes the findings of a study conducted on the Eastern Watersheds of Lake Lavon, Lake Ray Hubbard, Lake Tawakoni, Lake Palestine and Lake Fork, which are located within the Blackland Prairie, Post Oak Savannah and Pineywoods provinces. These watersheds are among nine that provide drinking water to Dallas, Texas. The study examines the potential benefit of "remote sensing and geographic information systems (GIS) for watershed management" in these five watersheds (p. iii). digital.library.unt.edu/ark:/67531/metadc29400/
- Remote Sensing and GIS for Nonpoint Source Pollution Analysis in the City of Dallas' Western Watersheds
- This report describes the findings of a study conducted on the watersheds of "Lake Lewisville, Lake Ray Roberts, Lake Grapevine and the Elm Fork of the Trinity River between Lake Lewisville and Frazier Dam," which are all part of the upper Trinity drainage basin (p. 31). The study examines the potential benefit of "remote sensing and geographic information systems (GIS) for watershed management" in and around Dallas, Texas (p. i). digital.library.unt.edu/ark:/67531/metadc29399/
- Historic Archaeology of the Johnson and Jones Farmsteads in the Ray Roberts Lake Area: 1850-1950
- This study represents the findings of research done on the Jones and Johnson farms, "situated in Johnson Branch Park in the north-central portion of the Ray Roberts Lake area." The purpose of the study was to offset future disturbances and damages to these farmsteads, and it includes "archival investigations, architectural documentation, oral-history interviews of long-time area residents and family members, farm equipment and artifact analyses, archaeological excavations, stabilization measures, and the development of interpretative exhibits for area schools, museums, and the general public" (p. i). digital.library.unt.edu/ark:/67531/metadc29393/
- Young Latinos Use of Mobile Phones: A Cross-Cultural Study
- This article is about a study designed to analyze how young people, operationalized in this study as people of Latino descent between the ages of 18-25, are using their mobile phone for various applications and what particular gratifications they derive from using the phone. But this study takes on a much larger dimension, because it involves a cross-cultural strategy. Research partners were recruited in five Latin American countries: Mexico, Colombia, Argentina, Chile and Uruguay, in order to collect data and compare it to other countries and to what is happening in the United States. digital.library.unt.edu/ark:/67531/metadc30853/
- The Media and Communication Industries: A 21st Century Perspective
- This article discusses the media and communication industry. Abstract: The media and communication industries are experiencing unprecedented change and evolution in the 21st century. This article examines this process with a case study method by analyzing the traditional and new media sectors using the following criteria: the markets in which they are engaged, the leaders in each of the respective industries, the economic potential of these industries, and their continuing evolution and transforming processes. The article argues that the media and communications industries can no longer be identified in terms of core sectors such as broadcasting or newspapers, but rather to a different structure of activities involving such areas as content, distribution, and search features. Further, the paper posits that new theoretical and methodological tools are needed by scholars to better understand the massive changes and transformation occurring across the media sector. A series of propositions concludes the paper, offering a framework on which to build future research and analysis. digital.library.unt.edu/ark:/67531/metadc30854/
- Reversing the Bricks: The Evolution of ETDs at UNT
- This presentation discusses electronic theses and dissertations (ETDs). Beginning in fall 1999, UNT has required the submission of theses and dissertations in electronic format. As an early adopter of what was to become the electronic thesis and dissertation (ETD) movement in higher education, UNT encountered and overcame several challenges in the pursuit of providing greater public access to the scholarship conducted at the University. Dr. Terrell was there from the very beginning, and will share her unique perspective on how far the ETD movement has come, and what challenges remain. digital.library.unt.edu/ark:/67531/metadc32968/
- UNT Wellness Initiative
- This presentation is part of the faculty lecture series UNT Speaks Out, the Symposium on Well-Being. In this presentation, the author discusses the importance of quality of life to achieve happiness and wellness. digital.library.unt.edu/ark:/67531/metadc33119/
- U.S. Mexico Migration
- This presentation is part of the faculty lecture series UNT Speaks Out on Unauthorized Immigration. This presentation discusses immigration, specifically between the United States and Mexico. digital.library.unt.edu/ark:/67531/metadc33118/
- Who Are These Unauthorized Immigrants and What Are We Going To Do About Them?
- This presentation is part of the faculty lecture series UNT Speaks Out on Unauthorized Immigration. This presentation discusses immigration in the United States, unauthorized immigration, and policies in place on immigration. digital.library.unt.edu/ark:/67531/metadc36278/
- The History Engine: Doing History with Digital Tools
- This article discusses the History Engine project. One of the primary goals of the History Engine project has been to design a research and writing exercise modest enough in its analytical scope and its length that it allows students to "do history" long before a senior seminar or capstone course. Another important goal, discussed in this article, is to capture this research to amass a large history archive. digital.library.unt.edu/ark:/67531/metadc36311/
- Peer Review and the Ex Ante Assessment of Societal Impacts
- This article discusses peer review. Funding agencies and research councils around the world rely on peer review to assess the potential impacts of proposed research. This article compares the procedures of two major public science agencies - the US National Science Foundation and the European Commission's 7th Framework Programme - for evaluating ex ante the potential societal impact of research proposals. In this paper the authors survey the state of the art and discuss some of the conceptual questions that arise in using ex ante peer review to assess the societal impact of scientific research. digital.library.unt.edu/ark:/67531/metadc38888/
- Discourse Variations Between Usability Tests and Usability Reports
- This article discusses the discourse variations between usability tests and usability reports. Abstract: While usability evaluation and usability testing has become an important tool in artifact assessment, little is known about what happens to usability data as it moves from usability session to usability report. In this ethnographic case study, the author investigates the variations in the language used by usability participants in user-based usability testing sessions as compared to the language used by novice usability testers in their oral reports of that usability testing session. In these comparative discourse analyses, the author assesses the consistency and continuity of the usability testing data within the purview of the individual testers conducting "do-it-yourself" usability testing. This case study of a limited population suggests that findings in oral usability reports may or may not be substantiated in the evaluations themselves, that explicit or latent biases may affect the presentation of the findings in the report, and that broader investigations, both in terms of populations and methodologies, are warranted. digital.library.unt.edu/ark:/67531/metadc38891/
- The Sword of Data: Does Human-Centered Design Fulfill Its Rhetorical Responsibility?
- This article discusses human-centered design. For more than two decades, user-centered design (UCD) has been the guiding philosophy and process in the field of design from both practice and pedagogy perspectives. Although there is no singular agreement on just what constitutes UCD and many different names for and "flavors" of UCD have emerged - human-centered design, just to name a few-nearly every version relies on an early and continual interaction with people who will actually use the product. Designers then use findings from the interactions (e.g. surveys, focus groups, card sorting exercises, document reviews, scenario-based testing, and plus-mining testing) to guide the design solutions. digital.library.unt.edu/ark:/67531/metadc38883/
- Defending Design Decisions With Usability Evidence: A Case Study
- This paper discusses a case study on defending design decisions with usability evidence. This case study takes a close look at what novice designers discursively use as evidence to support design decisions. User-centered design has suggested that all design decisions should be made with the concern for the user at the forefront, and, ideally, this concern should be represented by findings discovered within user-centered research. However, the data from a 12-month longitudinal study suggests that although these novice designers are well versed with user-centered design theory, in practice they routinely do not use user-centered research findings to defend their design decisions. Instead these novice designers use less definitive and more designer-centered forms of evidence. This move away from the user, though perhaps unintentional, may suggest that design pedagogy may need to be re-evaluated to ensure that novice designers continue to adhere to the implications of user-centered research throughout the design process. digital.library.unt.edu/ark:/67531/metadc38900/
- Decision-Making Strategies in Design Meetings
- This paper is about research on decision-making strategies in design meetings. Abstract: This project aims to further our understanding of the practice of user-centered design (UCD) by observing the argumentation strategies used by designers in face-to-face meetings in the critical periods between usability research and prototype iteration. In order to conduct such an investigation, the author recorded ten meetings of graduate student designers charged with redesigning documents for the United States Postal Service. The author then used discourse analysis techniques to determine how the designers used findings from research phases as evidence to support proposed design decisions in meetings concerning prototype alterations. Results show that these designers overwhelmingly do not support their design decisions with specific evidence from usability studies. This neglect of research-based evidence may indicate that these novice UCD designers may resort to designer-centric design behaviors in decision-making periods. The authors' analysis will focus on the rhetorical reasons why designers may avoid research-based evidence. digital.library.unt.edu/ark:/67531/metadc38899/
- [Review] Communications and Management at Work
- This book review discusses 'Communication and Management at Work' by Thomas Klikauer. The book, intended primarily for scholars of management, business, and organizational communication, invokes the theories of Kant, Habermas, Orwell, and Marx to assess at a macro level the historical and contemporary relationships between communication and control in the workplace. digital.library.unt.edu/ark:/67531/metadc38898/
- [Review] Nexus of Empire: Negotiating Loyalty and Identity in the Revolutionary Borderlands
- This book review discusses 'Nexus of Empire: Negotiating Loyalty and Identity in the Revolutionary Borderlands' edited by Gene Allen Smith and Sylvia L. Hilton. The book examines the individuals who inhabited the Gulf of Mexico regions, analyzing the ways in which these people defined and redefined themselves amid a world of competing loyalties. digital.library.unt.edu/ark:/67531/metadc39329/
- Examining Error in the Technical Communication Editing Test
- This paper discusses examining errors in technical communication. Abstract: Usage error is a popular topic for technical communicators. However, its anecdotal discussions remain the best source of information on the errors that technical communicators might value over others. In this paper, the author reports the types and frequencies of errors found in 41 editing tests administered to prospective technical writers and editors. Results indicate that misspellings and faulty/missing capitalization were the most frequent and dispersed errors. Eight of the most frequent errors related to style; however, grammar punctuation errors remain the most dispersed. A larger dataset will better determine how technical communicators prioritize specific errors. digital.library.unt.edu/ark:/67531/metadc39326/
- Unions of Slavery: Slavery, Politics, and Secession in the Valley of Virginia
- This book chapter discusses slavery, politics, and secession in the Valley of Virginia. digital.library.unt.edu/ark:/67531/metadc39316/
- Correlation Function and Generalized Master Equation of Arbitrary Age
- This article discusses correlation function and generalized master equation of arbitrary age. Abstract: We study a two-state statistical process with a non-Poisson distribution of sojourn times. In accordance with earlier work, we find that this process is characterized by aging and we study three different ways to define the correlation function of arbitrary age of the corresponding dichotomous fluctuation. These three methods yield exact expressions, thus coinciding with the recent result by Godrèche and Luck [J. Stat. Phys. 104, 489 (2001)]. Actually, non-Poisson statistics yields infinite memory at the probability level, thereby breaking any form of Markovian approximation, including the one adopted herein, to find an approximated analytical formula. For this reason, we check the accuracy of this approximated formula by comparing it with the numerical treatment of the second of the three exact expressions. We find that, although not exact, a simple analytical expression for the correlation function of arbitrary age is very accurate. We establish a connection between the correlation function and a generalized master equation of the same age. Thus this formalism, related to models used in glassy materials, allows us to illustrate an approach to the statistical treatment of blinking quantum dots, bypassing the limitations fo the conventional Liouville treatment. digital.library.unt.edu/ark:/67531/metadc40401/
- Brain, Music, and Non-Poisson Renewal Processes
- This article discusses brain, music, and non-Poisson renewal processes. Abstract: In this paper we show that both music composition and brain function, as revealed by the electroencephalogram (EEG) analysis, are renewal non-Poisson processes living in the nonergodic dominion. To reach this important conclusion the authors process the data with the minimum spanning tree method, so as to detect significant events, thereby building a sequence of times, which is the time series to analyze. The the authors show that in both cases, EEG and music composition, these significant events are the signature of a non-Poisson renewal process. This conclusion is reached using a technique of statistical analysis recently developed by the authors' group, the aging experiment (AE). First, the authors find that in both cases the distances between two consecutive events are described by nonexponential histograms, thereby proving the non-Poisson nature of these processes. The corresponding survival probabilities ψ(t) are well fitted by stretched exponentials [ψ(t) ∝ exp (-(yt)a), with 0.5<a<1.] The second step rests on the adoption of AE, which shows that these are renewal processes. The authors show that the stretched exponential, due to its renewal character, is the emerging tip of an iceberg, whose underwater part has slow tails with an inverse power law structure with power index μ=1+ơ. Adopting the AE procedure, the authors find that both EEG and music composition yield μ<2. On the basis of the recently discovered complexity driving signal P with μp⩽μs, the authors conclude that the results of their analysis may explain the influence of music on the human brain. digital.library.unt.edu/ark:/67531/metadc40398/
- Control of Root Architecture and Nodulation by the LATD/NIP Transporter
- This article discusses root architecture and nodulation. Abstract: The Medicago truncatula LATD/NIP gene is essential for the development of lateral and primary root and nitrogen-fixing nodule meristems as well as for rhizobial invasion of nodules. LATD/NIP encodes a member of the NRT1(PTR1) nitrate and di-and tri-peptide transporter family, suggesting that its function is to transport one of these or another compound(s). Because latd/nip mutants can have their lateral and primary root defects rescued by ABA, ABA is a potential substrate for transport. LATD/NIP expression in the root meristem was demonstrated to be regulated by auxin, cytokinin and abscisic acid, but not by nitrate. LATD/NIP's potential function and its role in coordinating root architecture and nodule formation are discussed. digital.library.unt.edu/ark:/67531/metadc40391/
- The AGC Kinase MtIRE: A Link to Phospholipid Signaling During Nodulation?
- This article discusses the AGC Kinase gene MtIRE. Abstract: The development of nitrogen fixing root nodules is complex and involves an interplay of signaling processes. During maturation of plant host cells and their endocytosed rhizobia in symbiosomes, host cells and symbiosomes expand. This expansion is accompanied by a large quantity of membrane biogenesis. The authors recently characterized an AGC kinase gene, MtIRE, that could play a role in this expansion. MtIRE's expression coincides with host cell and symbiosome expansion in the proximal side of the invasion zone in developing Medicago truncatula nodules. MtIRE's closest homolog is the Arabidopsis AGC kinase family IRE gene, which regulates root hair elongation. AGC kinases are regulated by phospholipid signaling in animals and fungi as well as in the several instances where they have been studied in plants. Here we suggest that a phospholipid signaling pathway may also activate MtIRE activity and propose possible upstream activators of MtIRE protein's presumed AGC kinase activity. digital.library.unt.edu/ark:/67531/metadc40414/
- Beyond the Death of Linear Response: 1/f Optimal Information Transport
- This article discusses linear response and 1/f optimal information transport. Article: Nonergodic renewal processes have recently been shown by several authors to be insensitive to periodic perturbations, thereby apparently sanctioning the death of linear response, a building block of nonequilibrium statistical physics. The authors show that it is possible to go beyond the "death of linear response" and establish a permanent correlation between an external stimulus and the response of a complex network generating nonergodic renewal processes, by taking as stimulus a similar nonergodic process. The ideal condition of 1/f noise corresponds to a singularity that is expected to be relevant in several experimental conditions. digital.library.unt.edu/ark:/67531/metadc40407/
- Complexity and Synchronization
- This article discusses complexity and synchronization. Abstract: We study a fully connected network (cluster) of interacting two-state units as a model of cooperative decision making. Each unit in isolation generates a Poisson process with rate g. We show that when the number of nodes is finite, the decision-making process becomes intermittent. The decision-time distribution density is characterized by inverse power-law behavior with index μ=1.5 and is exponentially truncated. We find that the condition of perfect consensus is recovered by means of a fat tail that becomes more and more extended with increasing numbers of nodes N. The intermittent dynamics of the global variable are described by the motion of a particle in a double well potential. The particle spends a portion of the total time τs at the top of the potential barrier. Using theoretical and numerical arguments it is proved that τs ∝ (1/g)1n(const X N). The second portion of its time, τk, is spent by the particle at the bottom of the potential well and it is given by τk=(1/g)exp(const X N). We show that the time τk is responsible for the Kramers fat tail. This generates a stronger ergodicity breakdown than that generated by the inverse power law without truncation. The authors establish that the condition of partial consensus can be transmitted from one cluster to another provided that both networks are in a cooperative condition. No significant information transmission is possible if one of the two networks is not yet self-organized. We find that partitioning a large network into a set of smaller interacting clusters has the effect of converting the fat Kramers tail into an inverse power law with μ=1.5. digital.library.unt.edu/ark:/67531/metadc40410/
- Dynamics of Electroencephalogram Entropy and Pitfalls of Scaling Detection
- This article discusses dynamics of electroencephalogram entropy and pitfalls of scaling detection. Abstract: In recent studies a number of research groups have determined that human electroencephalograms (EEG) have scaling properties. In particular, a crossover between two regions with different scaling exponents has been reported. Herein the authors study the time evolution of diffusion entropy to elucidate the scaling of EGG time series. For a cohort of 20 awake healthy volunteers with closed eyes, the authors find that the diffusion entropy of EEG increments (obtained from EEG waveforms by differencing) exhibits three features: short-time growth, an alpha wave related oscillation whose amplitude gradually decays in time, and asymptotic saturation which is achieved after approximately 1 s. This analysis suggests a linear, stochastic Ornstein-Uhlenbeck Langevin equation with a quasiperiodic forcing (whose frequency and/or amplitude may vary in time) as the model for the underlying dynamics. This model captures the salient properties of EEG dynamics. In particular, both the experimental and simulated EEG time series exhibit short-time scaling which is broken by a strong periodic component, such as alpha waves. The saturation of EEG diffusion entropy precludes the existence of asymptotic scaling. We find that the crossover between two scaling regions seen in detrended fluctuation analysis (DFA) of EEG increments does not originate from the underlying dynamics but is merely an artifact of the algorithm. This artifact is rooted in the failure of the "trend plus signal" paradigm of DFA. digital.library.unt.edu/ark:/67531/metadc40408/
- Dynamical Origin of Memory and Renewal
- This article discusses a dynamical origin of memory and renewal. Abstract: We show that the dynamic approach to fractional Brownian motion (FBM) establishes a link between a non-Poisson renewal process with abrupt jumps resetting to zero the system's memory and correlated dynamic processes, whose individual trajectories keep a nonvanishing memory of their past time evolution. It is well known that the recrossings of the origin by an ordinary one-dimensional diffusion trajectory generates a Lévy (and thus renewal) process of index θ=1/2. We prove with theoretical and numerical arguments that this is the special case of a more general condition, insofar as the recrossings produced by the dynamic FBM generates a Lévy process with 0<θ<1. This result is extended to produce a satisfactory model for the fluorescent signal of blinking quantum dots. digital.library.unt.edu/ark:/67531/metadc40399/
- Memory Effects in Fractional Brownian Motion with Hurst Exponent H<1/3
- In this article, the authors study the regression to the origin of a walker driven by dynamically generated fractional Brownian motion (FBM) and the authors prove that when the FBM scaling, i.e., the Hurst exponent H<1/3, the emerging inverse power law is characterized by a power index that is a compelling signature of the infinitely extended memory of the system. Strong memory effects leads to the relation H=θ/2 between the Hurst exponent and the persistent exponent θ, which is different from the widely used relation H=1 - θ. The latter is valid for 1/3<H<1 and is known to be compatible with the renewal assumption. digital.library.unt.edu/ark:/67531/metadc40405/
- Temporal Complexity of the Order Parameter at the Phase Transition
- In this article, the authors study a decision making model in a condition where it is equivalent to the two-dimensional Ising model, and the authors show that at the onset of phase transition it generates temporal complexity, namely, nonstationary and nonergodic fluctuations. The authors argue that this is a general property of criticality, thereby opening the door to the application of the recently discovered phenomenon of complexity matching: For an efficient transfer of information to occur, a perturbing complex network must share the same temporal complexity as the perturbed complex network. digital.library.unt.edu/ark:/67531/metadc40402/
- Renewal, Modulation, and Superstatistics in Times Series
- In this article, the authors consider two different approaches, to which the authors refer to as renewal and modulation, to generate time series with a nonexponential distribution of waiting times. The authors show that different time series with the same waiting time distribution are not necessarily statistically equivalent, and might generate different physical properties. Renewal generates aging and anomalous scaling, while modulation yields no significant aging and either ordinary or anomalous diffusion, according to the dynamic prescription adopted. The authors show, in fact, that the physical realization of modulation generates two classes of events. The events of the first class are determined by the persistent use of the same exponential time scale for an extended lapse of time, and consequently are numerous; the events of the second class are identified with the abrupt changes from one to another exponential prescription, and consequently are rare. The events of the second class, although rare, determine the scaling of the diffusion process, and for this reason the authors term them as crucial events. According to the prescription adopted to produce modulation, the distribution density of the time distances between two consecutive crucial events might have, or not, a diverging second moment. In the former case the resulting diffusion process, although going through a transition regime very extended in time, will eventually become anomalous. In conclusion, modulation rather than ruling out the action of renewal events, produces crucial events hidden by clouds of exponential events, thereby setting the challenge for their identification. digital.library.unt.edu/ark:/67531/metadc40400/
- Transmission of Information Between Complex Systems: 1/ f resonance
- In this article, the authors study the transport of information between two complex systems with similar properties. Both systems generate non-Poisson renewal fluctuations with a power-law spectrum 1/f 3-μ, the case μ=2 corresponding to ideal 1/f noise. The authors denote by μs and μp the power-law indexes of the system of interest S and the perturbing system P, respectively. By adopting a generalized fluctuation-dissipation theorem (FDT) the authors show that the ideal condition of 1/f noise for both systems corresponds to maximal information transport. The authors prove that to make the system S respond when μs < 2 the authors have to set the condition μp < 2. In the latter case, if μp < μs, the system S inherits the relaxation properties of the perturbing system. In the case where μp > 2, no response and no information transmission occurs in the long-time limit. The authors consider two possible generalizations of the fluctuation dissipation theorem and show that both lead to maximal information transport in the condition of 1/f noise. digital.library.unt.edu/ark:/67531/metadc40404/
- Spontaneous Brain Activity as a Source of Ideal 1/f Noise
- In this article, the authors study the electroencephalogram (EEG) of 30 closed-eye subjects with a technique of analysis recently proposed to detect punctual events signaling rapid transitions between different metastable states. After single-EEG-channel event detection, the authors study global properties of events simultaneously occurring among two or more electrodes termed coincidences. The authors convert the coincidences into a diffusion process with three distinct rules that can yield the same μ only in the case where the coincidences are driven by a renewal process. The authors establish that the time interval between two consecutive renewal events driving the coincidences has a waiting-time distribution with inverse power-law index μ≈2 corresponding to ideal 1/f noise. The authors argue that this discovery, shared by all subjects of our study, supports the conviction that 1/f noise is an optimal communication channel for complex networks as in art or language and may therefore be the channel through which the brain influences complex processes and is influenced by them. digital.library.unt.edu/ark:/67531/metadc40409/
- Non-Poisson Dichotomous Noise: Higher-Order Correlation Functions and Aging
- In this article, the authors study a two-state symmetric noise, with a given waiting time distribution ψ(τ), and focus their attention on the connection between the four-time and two-time correlation functions. The transition of ψ(τ) from the exponential to the nonexponential condition yields the breakdown of the usual factorization condition of high-order correlation functions, as well as the birth of aging effects. The authors discuss the subtle connections between these two properties and establish the condition that the Liouville-like approach has to satisfy in order to produce a correct description of the resulting diffusion process. digital.library.unt.edu/ark:/67531/metadc40403/
- Rapid Analysis of Legume Root Nodule Development Using Confocal Microscopy
- This article discusses the rapid analysis of legume root nodule development using confocal microscopy. A rapid method for detailed analysis of nodule formation has been developed. Inoculated root tissues were stained with SYTO 13, a cell-permeant fluorescent nucleic acid-binding dye, and visualized using confocal laser scanning microscopy (CLSM). Structures with high concentrations of DNA and RNA, such as plant cell nuclei and bacteria, labeled strongly. The autofluorescent properties of cell walls made it possible to use CLSM to visualize both plant and rhizobial structures and generate a three-dimensional reconstruction of the root and invading bacteria. This method allowed clear observation of stages and structures important in nodule formation, such as rhizobial attachment to root hairs, hair deformation, infection thread ramification, nodule primordium development and nodule cell invasion. Bacteroid structures were easily were easily assessed without the need for fixation that might alter cellular integrity. Plant nodulation mutants with phenotypic differences in thread growth, cellular invasion and plant defense response were also documented. Multiple samples can be assessed using detailed microscopy without the need for extensive preparative work, labor-intensive analysis, or the generation of genetically modified samples. digital.library.unt.edu/ark:/67531/metadc40415/
- A Putative Transporter is Essential for Integrating Nutrient and Hormone Signaling with Lateral Root Growth and Nodule Development in Medicago truncatula
- This article discusses a putative transporter for integrating nutrient and hormone signaling with lateral root growth and nodule development in Medicago truncatula. Legume root architecture involves not only elaboration of the root system by the formation of lateral roots but also the formation of symbiotic root nodules in association with nitrogen-fixing soil rhizobia. The Medicago truncatula LATD/NIP gene plays an essential role in the development of both primary and lateral roots as well as nodule development. We have cloned the LATD/NIP gene and show that it encodes a member of the NRT1(PTR) transporter family. LATD/NIP is expressed throughout the plant. pLATD/NIP-GFP promoter-reporter fusions in transgenic roots establish the spatial expression of LATD/NIP in primary root, lateral root and nodule meristems and the surrounding cells. Expression of LATD/NIP is regulated by hormones, in particular by abscisic acid which has been previously shown to rescue the primary and lateral root meristem arrest of latd mutants. latd mutants respond normally to ammonium but have defects in responses of the root architecture to nitrate. Taken together, these results suggest that LATD/NIP may encode a nitrate transporter or transporter of another compound. digital.library.unt.edu/ark:/67531/metadc40412/
- Sun-Climate Complexity Linking
- This article discusses sun-climate complexity linking. It is known that Earth's short-term temperature anomalies share the same complexity index μ as solar flares. The authors show that this property is not accidental and is a consequence of the phenomenon of information transfer based on the crucial role of non-Poisson renewal events in complex networks. digital.library.unt.edu/ark:/67531/metadc40396/
- Non-Markovian Nonstationary Completely Positive Open-Quantum-System Dynamics
- This article discusses non-Markovian nonstationary completely positive open-quantum-system dynamics. By modeling the interaction of a system with an environment through a renewal approach, the authors demonstrate that completely positive non-Markovian dynamics may develop some unexplored nonstandard statistical properties. The renewal approach is defined by a set of disruptive events, consisting in the action of a completely positive superoperator over the system density matrix. The random time intervals between events are described by an arbitrary waiting-time distribution. The authors show that, in contrast to the Markovian case, if one performs a system preparation (measurement) at an arbitrary time, the subsequent evolution of the density-matrix evolution is modified. The nonstationary character refers to the absence of an asymptotic master equation even when the preparation is performed at arbitrary long times. In spite this property, the authors demonstrate that operator expectation values and operators correlations have the same dynamical structure, establishing the validity of a nonstationary quantum regression hypothesis. The nonstationary property of the dynamics is also analyzed through the response of the system to an external weak perturbation. digital.library.unt.edu/ark:/67531/metadc40393/
- Publisher's Note: Beyond the Death of Linear Response: 1/f Optimal Information Transport [Phys. Rev. Lett. 105,040601 (2010)]
- This is a Publisher's Note for the article 'Beyond the Death of Linear Response: 1/f Optimal Information Transport' [Phys. Rev. Lett. 105, 040601 (2010)]. digital.library.unt.edu/ark:/67531/metadc40406/
- Criticality and Transmission of Information in a Swarm of Cooperative Units
- This article discusses criticality and transmission of information in a swarm of cooperative units. Abstract: We show that the intelligence of a swarm of cooperative units (birds) emerges at criticality, as an effect of the joint action of frequent organizational collapses and of spatial correlation as extended as the flock size. The organizational collapses make the birds become independent of one another, thereby allowing the flock to follow the direction of the lookout birds. Long-range correlation violates the principle of locality, making the lookout birds transmit information on either danger or resources with a time delay determined by the time distance between two consecutive collapses. digital.library.unt.edu/ark:/67531/metadc40392/
- Event-Driven Power-Law Relaxation in Weak Turbulence
- This article discusses event-driven power-law relaxation in weak turbulence. Abstract: We characterize the spectral properties of weak turbulence in a liquid crystal sample driven by an external electric field, as a function of the applied voltage, and we find a 1/f noise spectrum S(f) ∝ 1/fn within the whole range 0< ɳ <2. We theoretically explore the hypothesis that the system complexity is driven by non-Poisson events resetting the system through creation and annihilation of coherent structures, retaining no memory of previous history (crucial events). The authors study the time asymptotic regime by means of the density ψ(τ) of the time distances between two crucial events, yielding ɳ = 3 - μ, where μ is defined through the long-time form ψ(τ) ∝ 1/τµ, with 1 < µ < 3. The system regression to equilibrium after an abrupt voltage change experimentally confirms the theory, proving violations of the ordinary linear response theory for both ɳ > 1 and ɳ < 1. digital.library.unt.edu/ark:/67531/metadc40395/
- Experimental Quenching of Harmonic Stimuli: Universality of Linear Response Theory
- This article discusses experimental quenching of harmonic stimuli. Abstract: We show that liquid crystals in the weak turbulence electroconvective regime respond to harmonic perturbations with oscillations whose intensity decay with an inverse power law of time. We use the results of this experiment to prove that this effect is the manifestation of a form of linear response theory (LRT) valid in the out-of-equilibrium case, as well as at thermodynamic equilibrium where it reduces to the ordinary LRT. We argue that this theory is a universal property, which is not confined to physical processes such as turbulent or excitable media, and that it holds true in all possible conditions, and for all possible systems, including a complex networks, thereby establishing a bridge between statistical physics and all the fields of research in complexity. digital.library.unt.edu/ark:/67531/metadc40394/
- Fluctuation-Dissipation Theorem for Event-Dominated Processes
- This article discusses fluctuation-dissipation theorem for event-dominated processes. Abstract: We study a system whose dynamics are driven by non-Poisson, renewal, and nonergodic events. We show that external perturbations influencing the times at which these events occur violate the standard fluctuation-dissipation prescription due to renewal aging. The fluctuation-dissipation relation of this Letter is shown to be the linear response limit of an exact expression that has been recently proposed to account for the luminescence decay in a Gibbs ensemble of semiconductor nanocrystals, with intermittent fluorescence. digital.library.unt.edu/ark:/67531/metadc40397/
- An IRE-Like AGC Kinase Gene, MtIRE, Has Unique Expression in the Invasion Zone of Developing Root Nodules in Medicago truncatula
- This article discusses AGC kinase genes. Abstract: The AGC protein kinase family (cAMP-dependent protein kinases A, cGMP-dependent protein kinases G, and phospholipid-dependent protein kinases C) have important roles regulating growth and development in animals and fungi. They are activated via lipid second messengers by 3-phosphoinositide-dependent protein kinase coupling lipid signals to phosphorylation of the AGC kinases. These phosphorylate downstream signal transduction protein targets. AGC kiinases are becoming better studied in plants, especially in Arabidopsis (Arabidopsis thaliana), where specific AGC kinases have been shown to have key roles in regulating growth signal pathways. The authors report here the isolation and characterization of the first AGC kinase gene identified in Medicago truncatula, MtIRE. It was cloned by homology with the Arabidopsis INCOMPLETE ROOT HAIR ELONGATION (IRE) gene. Semiquantitative reverse transcription-polymerase chain reaction analysis shows that, unlike its Arabidopsis counterpart, MtIRE is not expressed in uninoculated roots, but is expressed in root systems that have been inoculated with Sinorhizobium meliloti and are developing root nodules. MtIRE expression is also found in flowers. Expression analysis of a time course of nodule development and of nodulating root systems of many Medicago nodulation mutants shows MtIRE expression correlates with infected cell maturation during nodule development. During the course of these experiments, nine Medicago nodulation mutants, including sli and dnf1 to 7 mutants, were evaluated for the first time for their microscopic nodule phenotype using S. meliloti constitutively expressing lacZ. Spatial localization of a pMtIRE-gusA transgene in transformed roots of composite plants showed that MtIRE expression is confined to the proximal part of the invasion zone, zone II, found in indeterminate nodules. This suggests MtIRE is useful as an expression marker for this region of the invasion zone. digital.library.unt.edu/ark:/67531/metadc40389/
- LIN, a Medicago truncatula Gene Required for Nodule Differentiation and Persistence of Rhizobial Infections
- This article discusses LIN, a Medicago truncatula gene. Abstract: Ethyl methanesulfonate mutagenesis of the model legume Medicago truncatula has previously identified several genes required for early steps in nodulation. Here, the authors describe a new mutant that is defective in intermediate steps of nodule differentiation. The lin (lumpy infections) mutant is characterized by a 4-fold reduction in the number of infections, all of which arrest in the root epidermis, and by nodule primordia that initiate normally but fail to mature. Genetic analyses indicate that the symbiotic phenotype is conferred by a single gene that maps to the lower arm of linkage group 1. Transcriptional markers for early Nod factor responses (RIP1 and ENOD40) are induced in lin, as is another early nodulin, ENOD20, a gene expressed during the differentiation of nodule primordia. By contrast, other markers correlated with primordium differentiation (CCS52A), infection progression (MtN6), or nodule morphogenesis (ENOD2 and ENOD8) show reduced or no induction in homozygous lin individuals. Taken together, these results suggest that LIN functions in maintenance of rhizobial infections and differentiation of nodules from nodule primordia. digital.library.unt.edu/ark:/67531/metadc40388/
- Absorption and Emission in the Non-Poissonian Case
- This article discusses absorption and emission in the Non-Poissonian Case. Abstract: This Letter addresses the challenging problems posed to the Kubo-Anderson (KA) theory by the discovery of intermittent resonant fluorescence with a nonexponential distribution of waiting times. We show how to extend the KA theory from aged to aging systems, aging for a very extended time period or even forever, being a crucial consequence of non-Poisson statistics. digital.library.unt.edu/ark:/67531/metadc67641/
- Aging and Rejuvenation with Fractional Derivatives
- This article discusses aging rejuvenation with fractional derivatives. Abstract: We discuss a dynamic procedure that makes a fractional derivatives emerge in the time asymptotic limit of non-Poisson processes. We find that two-state fluctuations, with an inverse power-law distribution of waiting times, finite first moment, and divergent second moment, namely, with the power index μ in the interval 2<μ<3, yield a generalized master equation equivalent to the sum of an ordinary Markov contribution and a fractional derivative term. We show that the order of the fractional derivative depends on the age of the process under study. If the system is infinitely old, the order of the fractional derivative, o, is given by o=3-μ. A brand new system is characterized by the degree o=μ-2. If the system is prepared at time -tₐ<0 and the observation begins at time t=0, we derive the following scenario. For times 0<t«tₐ the system is satisfactorily described by the fractional derivative with o=3-μ. Upon time increase the system undergoes a rejuvenation process that in the time limit t⪢tₐ yields o=μ-2. The intermediate time regime is probably incompatible with a picture based on fractional derivatives, or, at least, with a mono-order fractional derivative. digital.library.unt.edu/ark:/67531/metadc67638/
- What's Wrong with Processed Food?
- This presentation is part of the faculty lecture series UNT Speaks Out on the Food We Eat. The topics include what processed food is, genetically-modified foods, functional foods, and the impacts of processed foods. digital.library.unt.edu/ark:/67531/metadc67609/
- Diffusion Entropy and Waiting Time Statistics of Hard-X-Ray Solar Flares
- This article discusses diffusion entropy and waiting time statistics of hard-x-ray solar flares. Abstract: We show at work a technique of scaling detection based on evaluating the Shannon entropy of the diffusion process obtained by converting the time series under study into trajectories. This method, called diffusion entropy, affords information that cannot be derived from the direct evaluation of waiting times. We apply this method to the analysis of the distribution of time distance τ between two nearest-neighbor solar flares. This traditional part of the analysis is based on the direct evaluation of the distribution function ψ(τ), or of the probability ψ(τ), that no time distance smaller than a given τ is found. We adopt the paradigm of the inverse power-law behavior, and the authors focus on the determination of the inverse power index μ, without ruling out different asymptotic properties that might be revealed, at larger scales, with the help of richer statistics. We then use the DE method, with three different walking rules, and the authors focus on the regime of transition to scaling. This regime of transition and the value of the scaling parameter itself, δ, depends on the walking rule adopted, a property of interest to shed light on the slow process of transition from dynamics to thermodynamics often occurring under anomalous statistical conditions. With the first two rules the transition regime occurs through-out a large time interval, and the information contained in the time series is transmitted, to a great extent, to it, as well as to the scaling regime. By using the third rule, on the contrary, the same information is essentially conveyed to the scaling regime, which, in fact, emerges very quickly after a fast transition process. We show that the DE method not only causes to emerge the long-range correlation with a given μ<3, and so a basin of attraction different from the ordinary Gaussian one, but it also reveals the presence of memory effects induced by the time dependence of the solar flare rate. When this memory is annihilated by shuffling, the scaling parameter δ is shown to fit the theoretically expected function of μ. All this leads us to the compelling conclusion that μ=2.138±0.01. digital.library.unt.edu/ark:/67531/metadc67629/
- Scaling Detection in Time Series: Diffusion Entropy Analysis
- This article discusses scaling detection in time series. The methods currently used to determine the scaling exponent of a complex dynamic process described by a time series are based on the numerical evaluation of variance. This means that all of them can be safely applied only to the case where ordinary statistical properties hold true even if strange kinetics are involved. The authors illustrate a method of statistical analysis based on the Shannon entropy of the diffusion process generated by the time series, called diffusion entropy analysis (DEA). The authors adopt artificial Gauss and Lévy time series, as prototypes of ordinary and anomalous statistics, respectively, and the authors analyze them with the DEA and four ordinary methods of analysis, some of which are very popular. The authors show that the DEA determines the correct scaling exponent even when the statistical properties, as well as the dynamic properties, are anomalous. The other four methods produce correct results in the Gauss case but fail to detect the correct scaling in the case of Lévy statistics. digital.library.unt.edu/ark:/67531/metadc67632/