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Response to "A critique of Abraham and Acree's correlation for deca-1,9-diene/water partition coefficients"
This article is a response to "A critique of Abraham and Acree's correlation for deca-1,9-diene/water partition coefficients." Abstract: The manuscript responds to the critique of Nitsche and Kasting concerning our published correlation for deca-1,9-diene-water partition coefficients. Several statements made in the critique are refuded, and shown to be misrepresentations of ideas contained in our earlier paper. digital.library.unt.edu/ark:/67531/metadc152438/
The Biological and Toxicological Activity of Gases and Vapors
This article discusses the biological and toxicological activity of gases and vapors. Abstract: A large amount of data on the biological and toxicological activity of gases and vapors has been collected from the literature. Processes include sensory irritation thresholds, the Alarie mouse test, inhalation anasthesia, etc. It is shown that a single equation using only five descriptors (properties of the gases and vapors) plus a set of indicator variables for the given processes can correlate 643 biological and non-lethal toxicological activities of 'non-reactive' compounds with a standard deviation of 0.36 log unit. The equation is scaled to sensory irritation thresholds obtained by the procedure of Cometto-Muñiz, and Cain, and provides a general equation for the prediction of sensory irritation thresholds in man. It is suggested that differences in biological/toxicological activity arise primarily from transport from the gas phase to a receptor phase or area, except for odor detection thresholds where interaction with a receptor(s) is important. digital.library.unt.edu/ark:/67531/metadc152441/
IUPAC-NIST Solubility Data Series. 98. Solubility of Polycyclic Aromatic Hydrocarbons in Pure and Organic Solvent Mixtures: Revised and Updated. Part 1. Binary Solvent Mixtures
This article discusses the solubility of polycyclic aromatic hydrocarbons in pure and organic solvent mixtures. Abstract: This work updates Vols. 54, 58, and 59 in the IUPAC Solubility Data Series and presents solubility data for polycyclic aromatic hydrocarbon solutes dissolved in binary organic solvent mixtures. Published solubility data for anthracene, naphthalene, phenanthrene, phenothiazine, and pyrene that appeared in the primary literature between 1995 to the end of 2011 are compiled and critically evaluated. Experimental solubility data for 360 different solute-binary solvent systems are included in the volume. Solubility data published prior to 1995 were contained in three earlier volumes (Vols. 54, 58, and 59) and are not repeated in this volume. digital.library.unt.edu/ark:/67531/metadc152454/
IUPAC-NIST Solubility Data Series. 98. Solubility of Polycyclic Aromatic Hydrocarbons in Pure and Organic Solvent Mixtures: Revised and Updated. Part 2. Ternary Solvent Mixtures
This article discusses the solubility of polycyclic aromatic hydrocarbons in pure and organic solvent mixtures. Abstract: This work updates Vols. 54, 58, and 59 in the IUPAC Solubility Data Series and presents solubility data for polycyclic aromatic hydrocarbon solutes dissolved in ternary organic solvent mixtures. Published solubility data for anthracene, phenanthrene, and pyrene that appeared in the primary literature between 1995 to the end of 2011 are compiled and critically evaluated. Experimental solubility data for 119 different solute-ternary solvent systems are included in the volume. Solubility data published prior to 1995 were contained in three earlier volumes (Vols. 54, 58, and 59) and are not repeated here. digital.library.unt.edu/ark:/67531/metadc152455/
IUPAC-NIST Solubility Data Series. 98. Solubility of Polycyclic Aromatic Hydrocarbons in Pure and Organic Solvent Mixtures-Revised and Updated. Part 3. Neat Organic Solvents
This article discusses the solubility of polycyclic aromatic hydrocarbons in pure and organic solvent mixtures. Abstract: This work updates Vols. 54, 58, and 59 in the IUPAC Solubility Data Series and presents solubility data for polycyclic aromatic hydrocarbon solutes dissolved in neat organic solvents. Published solubility data for acenaphthene, anthracene, biphenyl, carbazole, dibenzofuran, dibenzothiophene, fluoranthene, fluorene, naphthalene, phenanthrene, phenothiazine, pyrene, thianthrene, and xanthene that appeared in the primary literature from 1995 to the end of 2011 are compiled and critically evaluated. Experimental solubility data for more than 550 different solute-organic solvent systems are included. Solubility data published prior to 1995 were contained in three earlier volumes (Vols. 54, 58, and 59) and are not repeated in this volume. digital.library.unt.edu/ark:/67531/metadc152456/
Solubility of Phenylacetic Acid in Binary Solvent Mixtures
This article discusses the solubility of phenylacetic acid in binary solvent mixtures. Abstract: Solubilities are reported for phenylacetic acid at 25.0 °C in binary mixtures of carbon tetrachloride with cyclohexane, n-heptane, n-octane, or isooctane and mixtures of cyclohexane with n-heptane or isooctane. The results are compared to the predictions of equations developed previously for solubility in systems of purely nonspecific interactions, with phenylacetic acid considered as either monomeric or dimeric molecules in solution. The dimer model provided the more accurate predictions and described the 15-fold range of solubilities in the carbon tetrachloride + isooctane system to within a maximum deviation of 15%. digital.library.unt.edu/ark:/67531/metadc152445/
Thermochemical Investigations of Gas-Liquid Chromatography. Partition Coefficients of Inert Solutes on Self-Associating Binary Solvent Mixtures
This article discusses partition coefficients of inert solutes on self-associating binary solvent mixtures. Abstract: A conventional nonelectrolyte solution model which has led to successful predictive equations for the partial molar excess properties of a solute in simple binary solvent systems is extended to include self-associating solvent components. An expression is developed and tested for its ability to describe gas-liquid partition coefficients in mixed solvents from measurements in the pure solvents. For n-hexane, n-heptane, and cyclohexane on blended mixtures of n-hexadecane and n-octadecane with N,N-dibutyl-2-ethylhexylamide, the newly derived expression is found to describe the chromatographic data to within 2%. digital.library.unt.edu/ark:/67531/metadc152444/
The transfer of neutral molecules, ions and ionic species from water to benzonitrile; comparison with nitrobenzene
This article discusses the transfer of neutral molecules, ions and ionic species from water to benzonitrile; comparison with nitrobenzene. Equations have been constructed for the transfer of 64 neutral solutes from water and from the gas phase to the solvent benzonitrile. The equations contain five descriptors and can be used to predict further values of the water-benzonitrile and gas-benzonitrile partition coefficients for a wide range of solutes. The water-benzonitrile equation has been extended to include ions and ionic species derived from acids by loss of a proton and bases by acceptance of a proton. Only two further descriptors are needed, one for anions and one for cations. A previous equation for transfer of neutral solutes from water to nitrobenzene has also been extended to include ions and ionic species. Comparison of the equations for transfer to benzonitrile and to nitrobenzene shows that the two solvents behave quite similarly, although benzonitrile as a solvent is a stronger hydrogen bond base. digital.library.unt.edu/ark:/67531/metadc157294/
Thermochemical Investigations of Nearly Ideal Binary Solvents. 3. Solubility in Systems of Nonspecific Interactions
This article discusses thermochemical investigations of nearly ideal binary solvents. Abstract: The simple model which has previously led to successful predictive equations for the partial molar excess enthalpy of a solute in nearly ideal binary solvents has been slightly modified for application to the partial molar excess Gibbs free energy (excess chemical potential) of the solute in these systems. Three predictive equations are derived and tested for their ability to predict solubility in mixed solvents from measurements in the pure solvents. The most successful equation involves volumetrically weighted interaction parameters for the excess Gibbs free energy relative to the Flory-Huggins entropy of mixing, and predicts solubility in 22 systems containing naphthalene, iodine, and stannic iodide as solutes with an average deviation of 1.5% and a maximum deviation of 4%, using no adjustable parameters. digital.library.unt.edu/ark:/67531/metadc152443/
Phase Transition Enthalpy Measurements of Organic and Organometallic Compounds. Sublimation, Vaporization and Fusion Enthalpies From 1880 to 2010
This article discusses phase transition enthalpy measurements of organic and organometallic compounds. A compendium of phase change enthalpies published within the period 1880-2010 is reported. Phase change enthalpies including fusion, vaporization, and sublimation are included for organic, organometallic, and a few inorganic compounds. This compendium is a combination of three previous series focusing on phase change enthalpies updated to 2009. Sufficient data are presently available for some compounds to permit thermodynamic cycles to be constructed, an important manner of evaluating the reliability of the measurements. Temperature adjustments of phase change enthalpies from the temperature of measurement to the standard reference temperature, T = 298.15 K, are briefly discussed and a protocol for doing so is illustrated. digital.library.unt.edu/ark:/67531/metadc152426/
Comment on the Prediction of Gas Chromatographic Retention Behavior with Mixed Liquid Phases
This article comments on the prediction of gas chromatographic retention behavior with mixed liquid phases. digital.library.unt.edu/ark:/67531/metadc146582/
Excess Molar Volumes of Binary Mixtures of Cyclohexane and y-Butyrolactone with Aromatic Hydrocarbons
This article discusses excess molar volumes of binary mixtures of cyclohexane and y-butyrolactone with aromatic hydrocarbons. Abstract: Excess molar volumes of cyclohexane + benzene, cyclohexane + toluene, cyclohexane + p-xylene, y-butyrolactone + benzene, y-butyrolactone + toluene, and y-butyrolactone + m-xylene have been measured at 298.15 K. For the first three systems, Vᴱ is positive throughout the entire concentration range. Vᴱ is negative for binary mixtures containing y-butyrolactone, which indicates significant interaction between y-butyrolactone and the aromatic hydrocarbon. digital.library.unt.edu/ark:/67531/metadc152457/
Comments on the Competitive Preferential Solvation Theory
This article offers comments on the competitive preferential solvation theory. Abstract: Simple additive relationships for the physico-chemical properties of a solute dissolved in binary solvent mixtures are developed from the competitive preferential solvation model. Additive expressions for solute mole fraction solubility and logarithm of solute solubility are mathematically identical to equations derived previously from the microscopic partition and basic nearly ideal binary solvent models. Calculated values based on the various additive relationships are compared to carbazole solubilities in ten binary solvent mixtures containing dibutyl ether with n-hexane, n-heptane, n-octane, cyclohexane, cyclo-octane, methylcyclohexane, iso-octane, n-hexadecane, squalane and t-butylcyclohexane. digital.library.unt.edu/ark:/67531/metadc157300/
UMTS Capacity and Throughput Maximization for Different Spreading Factors
This article discusses UMTS capacity and throughput maximization for different spreading factors. An analytical model for calculating capacity in multi-cell UMTS networks is presented. Capacity is maximized for different spreading factors and for perfect and imperfect power control. The authors also design and implement a local call admission control (CAC) algorithm which allows for the simulation of network throughput for different spreading factors and various mobility scenarios. The design of the CAC algorithm uses global information ; it incorporates the call arrival rates and the user mobilities across the network and guarantees the users' quality of service as well as pre-specified blocking probabilities. On the other hand, its implementation in each cell uses local information; it only requires the number of calls currently active in that cell. The capacity and network throughput were determined for signal-to-interference threshold from 5 dB to 10 dB and spreading factor values of 256, 64, 16, and 4. digital.library.unt.edu/ark:/67531/metadc30833/
Mobility-Based CAC Algorithm for Arbitrary Call-Arrival Rates in CDMA Cellular Systems
This paper presents a novel approach for designing a call-admission control (CAC) algorithm for code-division multiple-access (CDMA) networks with arbitrary call-arrival rates. The design of the CAC algorithm uses global information; it incorporates the call-arrival rates and the user mobilities across the network and guarantees the users' quality of service (QoS) as well as prescribed blocking probabilities. On the other hand, its implementation in each cell uses local information; it only requires the number of calls currently active in that cell. The authors present several cases for a nontrivial network topology where their CAC algorithm guarantees QoS and blocking probabilities while achieving significantly higher throughput than that achieved by traditional techniques. The authors also calculate the network capacity, i.e., the maximum throughput for the entire network, for prespecified blocking probabilities and QoS requirements. digital.library.unt.edu/ark:/67531/metadc30821/
Multicell CDMA Network Design
Traditional design rules for cellular networks are not directly applicable to code division multiple access (CDMA) networks where intercell interference is not mitigated by cell placement and careful frequency planning. For transmission quality requirements, a minimum signal-to-interface ratio (SIR) must be achieved. The base-station location, its pilot-signal power (which determines the size of the cell), and the transmission power of the mobiles all affect the received SIR. In addition, because of the need for power control in CDMA networks, large cells can cause a lot of interference to adjacent small cells, posing another constraint to design. In order to maximize the network capacity associated with a design, the authors develop a methodology to calculate the sensitivity of capacity to base-station location, pilot-signal power, and transmission power of each mobile. To alleviate the problem caused by difference cell sizes, the authors introduce the power compensation factor, by which the nominal power of the mobiles in every cell is adjusted. The authors then use the calculated sensitivities in an iterative algorithm to determine the optimal locations of the base stations, pilot-signal powers, and power compensation factors in order to maximize capacity. The authors show examples of how networks using these design techniques provide higher capacity than those designed using traditional techniques. digital.library.unt.edu/ark:/67531/metadc30815/
Non-Uniform Grid-Based Coordinated Routing in Wireless Sensor Networks
This paper presents a non-uniform grid-based coordinated routing design in wireless sensor networks. The conditions leading to network partition and analysis of energy consumption that prolongs the network lifetime are studied. The authors focus on implementing routing in densely populated sensor networks. By maintaining constant values for parameters such as path loss exponent, receiver sensitivity and transmit power, and varying between uniform and non-uniform grids, we observe energy consumption patterns for each of the grid structures and infer from the network lifetime the better suited grids for uniformly and randomly deployed sensor nodes. digital.library.unt.edu/ark:/67531/metadc30848/
Strategies for Retention and Recruitment of Women and Minorities in Computer Science and Engineering
This paper describes the efforts and results of a plan for actively recruiting students to undergraduate computer science and engineering programs at the University of North Texas (UNT). It also describes a series of activities aimed at improving retention rates of students already in computer science and engineering programs at UNT. Such recruitment and retention of students is critical to the country's efforts to increase the number of engineering professionals, and is a priority for the Computer Science and Engineering (CSE) Department at UNT. digital.library.unt.edu/ark:/67531/metadc30855/
Effects of Interference on Capacity in Multi-Cell CDMA Networks
This article discusses the effects of interference on capacity in multi-cell CDMA networks. Abstract: An overwhelming number of models in the literature use average interference for calculation of capacity of a CDMA network. In this paper, we calculate the actual per-user interference and analyze the effect of user-distribution on the capacity of a CDMA network. We show that even though the capacity obtained using average interference is a good approximation to the capacity calculated using actual interference for a uniform user distributions, the deviation can be tremendously large for non-uniform user distributions. We also present an analytical model for approximating the user distributions using 2-dimensional Gaussian distributions by determining the means and the standard deviations of the distributions for every cell. This allows us to calculate the inter-cell interference and the reverse-link capacity of the network. We compare their model with simulation results and show that it is fast and accurate enough to be used efficiently in the planning process of large CDMA networks. digital.library.unt.edu/ark:/67531/metadc30826/
Three Important Things to Consider When Starting Intervention for a Child Diagnosed with Autism
This article discusses important things to consider when starting an intervention for a child diagnosed with autism. The authors discuss questions that one should ask before beginning such an undertaking and important things to consider after the first year of intervention. digital.library.unt.edu/ark:/67531/metadc39324/
Emerging Opportunities in Higher Education: Applied Behavior Analysis and Autism
This article discusses applying behavior analysis to autism. Abstract: The growing number of children diagnosed with autism and the recognized importance of evidence-based interventions has substantially increased the need for well-trained applied behavior analysts. Relative to public/consumer demand, there are very few higher education programs that are equipped to train behavior analysts specializing in autism. Worldwide, there are only a few programs accredited by Association for Behavior Analysis International (ABAI), that have course sequences approved by the Behavior Analysis Certification Board (BACB), and have formal institutional course approval for classes in autism and behavior analysis. The purpose of this paper is to introduce a series of expert commentary on the context, content and systems required to build quality higher education programs in autism and applied behavior analysis. Together the articles in this special section of the European Journal of Applied Behavior Analysis form a resource for faculty and university administrators interested in the development of innovative and socially relevant training programs in higher education. digital.library.unt.edu/ark:/67531/metadc39323/
The Development of Interests in Children with Autism: A Method to Establish Baselines for Analyses and Evaluation
This article discusses development of interests in children with autism. Abstract: By definition, children with autism have limited interests. While considerable efforts have been directed toward the social and communication difficulties faced by children with autism, less attention has been directed towards understanding the development and acquisition of new interests. Such understanding may help autism interventionists-establish increasingly diverse and complex interests thereby increasing reinforcing events, learning opportunities, activity participation, and social engagement. This paper describes an observational system for monitoring reinforcer diversity and event engagement during naturalistic teaching portions of an early intervention program. Data are presented for two children. It is suggested that such measures are necessary for two reasons. First, given the lack of empirical support and the importance of reinforcers, there is a need for measurement systems to monitor the development of interests in early intervention programs for children with autism. Second, there is a paucity of research addressing expansion of interests. Developing measurement systems increases the likelihood that evidence-based practices will emerge. Hopefully, these efforts will increase our knowledge, increase child preference for instruction, and open avenues for enhanced instructional and life opportunities based on expanded interests. digital.library.unt.edu/ark:/67531/metadc39320/
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/
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/
Developing the ICT Infrastructure for Africa: Overview of Barriers to Harnessing the Full Power of the Internet
This article discusses developing the Information Communication Technologies (ICT) for Africa. Abstract: The synergies of numerous emerging trends are shaping creation, access, use and preservation of information resources. The digital library environment provides scholars with access to more diverse and previously unavailable contents that span myriad technologies across institutions and nations. Although the uses of Internet technologies provide new directions for scholarship, there are discrepancies among nations and regions. These technologies have not been fully exploited in Africa in particular. As research and scientific inquiry depend on both the availability of heterogeneous resources from multiple sources and their openness to easy and continued access, addressing the universal access is paramount. This article discusses and provides an overview of some of the barriers or principal factors most likely to influence Africa's efforts in harnessing the full power of the Internet. digital.library.unt.edu/ark:/67531/metadc38890/
Metadata Quality Assurance: The University of North Texas Libraries' Experience
This paper discusses issues related to metadata quality management and demonstrates a number of tools, workflows, and quality assurance mechanisms employed by the University of North Texas Libraries' Digital Projects Unit. digital.library.unt.edu/ark:/67531/metadc29320/
A Metadata Approach to Preservation of Digital Resources: The University of North Texas Libraries' Experience
This article discusses a metadata approach to preservation of digital resources. Preserving long-term access to digital information resources is one of the key challenges facing libraries and information centers today. The University of North Texas (UNT) Libraries has entered into partnership agreements with federal and state agencies to ensure permanent storage and public access to a variety of government information sources. As digital resource preservation encompasses a wide variety of interrelated activities, the UNT Libraries are taking a phased approach to ensure the long-term access to its digital resources. Formulation of preservation policy and creation of preservation metadata for electronic files and digital collections are among the most important steps. This paper discusses the issues related to digital resources preservation and demonstrates the role of preservation metadata in facilitating the preservation activities in general. In particular, it describes the efforts being made by the UNT Libraries to ensure the long-term access and preservation of various digital information resources. digital.library.unt.edu/ark:/67531/metadc29308/
Generalized Master Equation Via Aging Continuous-Time Random Walks
This article discusses generalized master equation via aging continuous-time random walks. Abstract: We discuss the problem of the equivalence between continuous-time random walk (CTRW) and generalized master equation (GME). The walker, making instantaneous jumps from one site of the lattice to another, resides in each site for extended times. The sojourn times have a distribution density ψ(t) that is assumed to be an inverse power law with the power index μ. We assume that the Onsager principle is fulfilled, and we use this assumption to establish a complete equivalence between GME and the Montroll-Weiss CTRW.We prove that this equivalence is confined to the case where ψ(t) is an exponential. We argue that is so because the Montroll-Weiss CTRW, as recently proved by Barkai [E. Barkai, Phys. Rev. Lett. 90, 104101 (2003)], is nonstationary, thereby implying aging, while the Onsager principle is valid only in the case of fully aged systems. The case of a Poisson distribution of sojourn times is the only one with no aging associated to it, and consequently with no need to establish special initial conditions to fulfill the Onsager principle. We consider the case of a dichotomous fluctuation, and we prove that the Onsager principle is fulfilled for any form of regression to equilibrium provided that the stationary condition holds true. We set the stationary condition on both the CTRW and the GME, thereby creating a condition of total equivalence, regardless of the nature of the waiting-time distribution. As a consequence of this procedure the authors create a GME that is a bona fide master equation, in spite of being non-Markov. We note that the memory kernel of the GME affords information on the interaction between system of interest and its bath. The Poisson case yields a bath with infinitely fast fluctuations. We argue that departing from the Poisson form has the effect of creating a condition of infinite memory and that these results might be useful to shed light on the problem of how to unravel non-Markov quantum master equations. digital.library.unt.edu/ark:/67531/metadc67635/
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/
Long- and Short-Time Analysis of Heartbeat Sequences: Correlation with Mortality Risk in Congestive Heart Failure Patients
This paper discusses long- and short-time analysis of heartbeat sequences and the correlation with mortality risk in congestive heart failure patients. Abstract: We analyze RR heartbeat sequences with a dynamic model that satisfactorily reproduces both the long- and the short-time statistical properties of heart beating. These properties are expressed quantitatively by means of two significant parameters, the scaling δ concerning the asymptotic effects of long-range correlation, and the quantity 1 - π establishing the amount of uncorrelated fluctuations. We find a correlation between the position in the phase space (δ,π) of patients with congestive heart failure and their mortality risk. digital.library.unt.edu/ark:/67531/metadc67633/
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/
Dynamical model for DNA sequences
This article discusses a dynamical model for DNA sequences. Abstract: We address the problem of DNA sequences, developing a "dynamical" method based on the assumption that the statistical properties of DNA paths are determined by the joint action of two processes, one deterministic with long-range correlations and the other random and δ-function correlated. The generator of the deterministic evolution is a nonlinear map belonging to a class of maps recently tailored to mimic the processes of weak chaos responsible for the birth of anomalous diffusion. It is assumed that the deterministic process corresponds to unknown biological rules that determine the DNA path, whereas the noise mimics the influence of an infinite-dimensional environment on the biological process under study. We prove that the resulting diffusion process, if the effect of the random process is determined by the joint action of the deterministic and the random process, the correlation effects of the "deterministic dynamics" are canceled on the short-range scale, but show up in the long-range one. We denote their prescription to generate statistical sequences as the copying mistake map (CMM). We carry out their analysis of several DNA sequences and their CMM realizations with a variety of techniques and the authors especially focus on a method of regression to equilibrium, which they call the Onsager analysis. With these techniques the authors establish the statistical equivalence of the real DNA sequences with their CMM realizations. We show that long-range correlations are present in exons as well as in introns, but are difficult to detect, since the exon "dynamics" is shown to be determined by the entanglement of three distinct and independent CMM's. digital.library.unt.edu/ark:/67531/metadc139499/
Scaling Breakdown: A Signature of Aging
In this article, the authors prove that the Lévy walk is characterized by bilinear scaling. This effect mirrors the existence of a form of aging that does not require the adoption of nonstationary conditions. digital.library.unt.edu/ark:/67531/metadc67630/
Compression and Diffusion: A Joint Approach to Detect Complexity
This article discusses a joint approach to detect complexity. Abstract: The adoption of the Kolmogorov-Sinai (KS) entropy is becoming a popular research tool among physicists, especially when applied to a dynamical system fitting the conditions of validity of the Pesin theorem. The study of time series that are a manifestation of system dynamics whose rules are either unknown or too complex for a mathematical treatment, is still a challenge since the KS entropy is not computable, in general, in that case. Here the authors present a plan of action based on the joint action of two procedures, both related to the KS entropy, but compatible with computer implementation through fast and efficient programs. The former procedure, called Compression Algorithm Sensitive To Regularity (CASToRe), establishes the amount of order by the numerical evaluation of algorithmic compressibility. The latter, called Complex Analysis of Sequences via Scaling AND Randomness Assessment (CASSANDRA), establishes the complexity degree through the numerical evaluation of the strength of an anomalous effect. This is the departure, of the diffusion process generated by the observed fluctuations, from ordinary Brownian motion. The CASSANDRA algorithm shares with CASToRe a connection with the Kolmogorov complexity. This makes both algorithms especially suitable to study the transition from dynamics to thermodynamics, and the case of non-stationary time series as well. The benefit of the joint action of these two methods is proven by the analysis of artificial sequences with the same main properties as the real time series to which the joint use of these two methods will be applied in future research work. digital.library.unt.edu/ark:/67531/metadc139462/
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/
Response of Complex Systems to Complex Perturbations: the Complexity Matching Effect
This article discusses the complexity matching effect. The dynamical emergence (and subsequent intermittent breakdown) of collective behavior in complex systems is described as a non-Poisson renewal process, characterized by a waiting-time distribution density ψ(T) for the time intervals between successfully recorded breakdowns. In the intermittent case ψ(t) ~ t-μ, with complexity index μ. The authors show that two systems can exchange information through complexity matching and present theoretical and numerical calculations describing a system with complexity index μs perturbed by a signal with complexity index μp. The analysis focuses on the non-ergodic (non-stationary) case μ ≤ 2 showing that for μs ≥ μp, the system S statistically inherits the correlation function of the perturbation P. The condition μp = μs is a resonant maximum for correlation information exchange. digital.library.unt.edu/ark:/67531/metadc132965/
Site correlation, anomalous diffusion, and enhancement of the localization length
This article discusses site correlation, anomalous diffusion, and enhancement of localization length. Herein the authors study the effects on Anderson localizations of correlations in the energy distribution of the sites of a tight-binding Hamiltonian. The lattice correlations are introduced are introduced by means of classical maps generating anomalous diffusion, that have recently been found to account for the correlated disorder of "biological" lattices. The authors show that the enhancement of localization length takes place on a much wider band of energies than in the case of the random-dimer model if the random walk on the site energies of the tight-binding Hamiltonian is determined by the joint action of short- and long-range correlations. digital.library.unt.edu/ark:/67531/metadc139487/
Fractional Brownian motion as a nonstationary process: An alternative paradigm for DNA sequences
This article discusses fractional Brownian motion as a nonstationary process. Abstract: The long-range correlations in DNA sequences are currently interpreted as an example of stationary fractional Brownian motion (FBM). First the authors show that the dynamics of a dichotomous stationary process with long-range correlations such as that used to model DNA sequences should correspond to Lévy statistics and not to FBM. To explain why, in spite of this, the statistical analysis of the data seems to be compatible with FBM, the authors notice that an initial Gaussian condition, generated by a process foreign to the mechanism establishing the long-range correlations and consequently implying a departure from the stationary condition is maintained approximately unchanged for very long times. This is so because due to the nature itself of the long-range correlation process, it takes virtually an infinite time for the system to reach the genuine stationary state. Then the authors discuss a possible generator of initial Gaussian conditions, based on a folding mechanism of the nucleic acid in the cell nucleus. The model adopted is compatible with the known biological and physical constraints, namely, it is shown to be consistent with the information of current biological literature on folding as well as with the statistical analyses of DNA sequences. digital.library.unt.edu/ark:/67531/metadc75416/
Non-Gaussian statistics of anomalous diffusion: The DNA sequences of prokaryotes
This article discusses non-Gaussian statistics of anomalous diffusion. The authors adopt a non-Gaussian indicator to measure the deviation from Gaussian statistics of a diffusion process generated by dichotomous fluctuations with infinite memory. The authors also make analytical predictions on the transient behavior of the non-Gaussian indicator as well as on its stationary value. The authors then apply this non-Gaussian analysis to the DNA sequences of prokaryotes adopting a theoretical model where the "DNA dynamics" are assumed to be determined by the statistical superposition of two independent generators of fluctuations: a generator of fluctuations with no correlation and a generator of fluctuations with infinite correlation "time". The authors study also the influence that the finite length of the observed sequences has on the short-range fluctuation and sequence truncation. Nevertheless, under proper conditions, fulfilled by all the DNA sequences of prokaryotes that have been examined, a non-Gaussian signature remains to signal the correlated nature of the driving process. digital.library.unt.edu/ark:/67531/metadc75418/
Dynamical approach to Lévy processes
This article discusses a dynamical approach to Lévy processes.Abstract: We derive the diffusion process generated by a correlated dichotomous fluctuating variable y starting from a Liouville-like equation by means of a projection procedure. This approach makes it possible to derive all statistical properties of the diffusion process from the correlation function of the dichotomous fluctuating variable Φy(t). Of special interest is that the distribution of the times of sojourn in the two states of the fluctuating process is proportional to d²Φy(t)/dt². Furthermore, in the special case where Φy(t) has an inverse power law, with the index β ranging from 0 to 1, thus making it nonintegrable, the authors show analytically that the statistics of the diffusing variable approximate in the long-time limit the α-stable Lévy distributions. The departure of the diffusion process of dynamical origin from the ideal condition of the Lévy statistics is established by means of a simple analytical expression. We note, first of all, that the characteristic function of a genuine Lévy process should be an exponential in time. We evaluate the correction to this exponential and show it to be expressed by a harmonic time oscillation modulated by the correlation function Φy(t). Since the characteristic function can be given a spectroscopic significance, we also discuss the relevance of the results within this context. digital.library.unt.edu/ark:/67531/metadc139498/
Memory Beyond Memory in Heart Beating, a Sign of a Healthy Physiological Condition
In this article, the authors describe two types of memory and illustrate each using artificial and actual heartbeat data sets. The first type of memory, yielding anomalous diffusion, implies the inverse power-law nature of the waiting time distribution and the second the correlation among distinct times, and consequently also the occurrence of many pseudoevents, namely, not genuinely random events. Using the method of diffusion entropy analysis, the authors establish the scaling that would be determined by the real events alone. The authors prove that the heart beating of healthy patients reveals the existence of many more pseudoevents than in the patients with congestive heart failure. digital.library.unt.edu/ark:/67531/metadc67628/
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/
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/
Strategic Planning of Technology for Education: A Beginning Framework
This article discusses a beginning framework for the strategic planning of technology in education. The strategic planning of technology framework introduced in this paper is broken into five distinct parts: student technology, teacher technology, teacher training, technology planning cycle, and technology cost. This framework is designed to assist technology planners, teachers (academic and vocational), and administrators as they begin planning for future technology implementation in their school district. digital.library.unt.edu/ark:/67531/metadc31066/
Training Older Workers: Implications for HRD/HPT Professionals
This article discusses training older workers. In corporations across America, a race is on to find new ways to maximize human capital. An emphasis on lifelong learning will be vital for the success of our future workforce. As demographic shifts occur, the "older worker" will emerge as a primary target for this human development effort. This article explores the implications of this demographic shift for the human resource development and human performance technology (HRD/HPT) professional and recommends strategies for meeting this business need. First, the authors discuss the realities of this demographic shift and compare our current workforce demographics to those of the future. Next, the authors examine the common myths about the "older worker", as well as what current research reports about this special population. Finally, the authors examine the impact of this trend on our profession. The authors discuss strategies for modifying the workplace environment, reassessing workforce motivational strategies, and altering training practices in order to serve this older worker population. In conclusion, the authors look at the implications for the future in HRD/HPT research. digital.library.unt.edu/ark:/67531/metadc31072/
Retrospective Pretest: A Practical Technique for Professional Development Evaluation
The purpose of this study was to field test an instrument incorporating a retrospective pretest to determine whether it could reliably be used as an evaluation tool for a professional development conference. Based on a prominent evaluation taxonomy, the instrument provides a practical, low-cost approach to evaluating the quality of professional development interventions across a wide variety of disciplines. The instrument includes not only the questions typically associated with measuring participants' reactions but also includes a set of questions to gauge whether and how much learning occurred. Results indicate that the data produced from the instrument were reliable. digital.library.unt.edu/ark:/67531/metadc31084/
Training Employees With Disabilities: Strategies from Corporate Training
This article focuses on the strategies used by corporate trainers to effectively teach populations with disabilities in their corporate workplace. Specifically, training strategies, both methods and training aids, for individuals with physical or mental disabilities are investigated. Both educators and trainers strive to effectively teach all learners. Corporate trainers have challenges that are similar to the challenges seen by educators. This article offers a different perspective for career and technology educators who are looking for new strategies to increase the impact of teaching methods in their classroom. digital.library.unt.edu/ark:/67531/metadc31065/
Investigating the Screwdriver: 25 Years of Technology Change
This article discusses changes in technology. Abstract: Technology can be defined as the utilization of theory, processes, information, and materials to improve the knowledge, skills, and attitudes of a society. Since 1973 there have been many technological changes in the field of vocational education. This article offers a broad look at some of the technology changes in the last 25 years, as well as strategies for implementation and planning in the new millennium. digital.library.unt.edu/ark:/67531/metadc31069/
Copyright and Fair Use: An Issue of Ethics in a Changing Learning Environment
This article discusses copyright issues. Abstract: Copyright infringement is one of the most talked about, yet most misunderstood topics in the curriculum and instructional development areas. The field of copyright protection is fraught with gray areas that undermine an individual's honest ability to discern what might be lawful uses of copyrighted materials. This article begins with a brief history of copyright law in the U.S. and provides examples, references, and discussion of "fair use." Additionally, issues related to the Internet are addressed, including: Web Linking, Framing, Plagiarism, Web-based referencing. Finally, considerations and suggestions for teaching and using ethical practices in the industrial and educational classroom are discussed. Fair use and copyright in educational institutions is largely an ethical issue. Ethics are not dependent on individual's actions. All parties involved must contribute to the ethical nature of an event and must accept both the responsibility for their actions or their non-actions. digital.library.unt.edu/ark:/67531/metadc31081/
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