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Partner: UNT College of Arts and Sciences
Year: 2003
Language: English
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### Cognitive Scale-Free Networks as a Model for Intermittency in Human Natural Language

Date: 2003
Creator: Allegrini, Paolo; Grigolini, Paolo & Palatella, Luigi
Description: Paper discussing cognitive scale-free networks as a model for intermittency in human natural language. Abstract: We model certain features of human language complexity by means of advanced concepts borrowed from statistical mechanics. Using a time series approach, the diffusion entropy method (DE), we compute the complexity of an Italian corpus of newspapers and magazines. We find that the anomalous scaling index is compatible with a simple dynamical model, a random walk on a complex scale-free network, which is linguistically related to Saussurre's paradigms. The model yields the famous Zipf's law in terms of the generalized central limit theorem.
Contributing Partner: UNT College of Arts and Sciences

### Compression and Diffusion: A Joint Approach to Detect Complexity

Date: February 2003
Creator: Allegrini, Paolo; Benci, V. (Vieri); Grigolini, Paolo; Hamilton, P.; Ignaccolo, Massimiliano; Menconi, Giulia et al.
Description: Article discussing a joint approach to detect complexity by combining the Compression Algorithm Sensitive To Regularity (CASToRe) and Complex Analysis of Sequences via Scaling AND Randomness Assessment (CASSANDRA) procedures.
Contributing Partner: UNT College of Arts and Sciences

### Decoherence, wave function collapses and non-ordinary statistical mechanics

Date: August 2003
Creator: Bologna, Mauro; Grigolini, Paolo; Pala, Marco G. & Palatella, Luigi
Description: Article discussing decoherence, wave function collapses, and non-ordinary statistical mechanics. Abstract: We consider a toy model of pointer interacting with a 1/2-spin system, whose $\sigma_{x}$ variable is \emph{measured} by the environment, according to the prescription of decoherence theory. If the environment measuring the variable $\sigma_{x}$ yields ordinary statistical mechanics, the pointer sensitive to the 1/2-spin system undergoes the same, exponential, relaxation regardless of whether real collapses or an entanglement with the environment, mimicking the effect of real collapses, occur. In the case of non-ordinary statistical mechanics the occurrence of real collapses make the pointer still relax exponentially in time, while the equivalent picture in terms of reduced density matrix generates an inverse power law relaxation.
Contributing Partner: UNT College of Arts and Sciences

### Detection of invisible and crucial events: from seismic fluctuations to the war against terrorism

Date: October 28, 2003
Creator: Allegrini, Paolo; Fronzoni, Leone; Grigolini, Paolo; Latora, Vito; Mega, Mirko S.; Palatella, Luigi et al.
Description: Paper discussing the detection of invisible and crucial events. Abstract: We argue that the recent discovery of the non-Poissonian statistics of the seismic main-shocks is a special case of a more general approach to the detection of the distribution of the time increments between one crucial but invisible event and the next. We make the conjecture that the proposed approach can be applied to the analysis of terrorist network with significant benefits for the Intelligence Community.
Contributing Partner: UNT College of Arts and Sciences

### Enthalpies of Vaporization of Organic and Organometallic Compounds, 1880-2002

Date: April 21, 2003
Creator: Chickos, James S. & Acree, William E. (William Eugene)
Description: This article discusses enthalpies of vaporization of organic and organometallic compounds. Abstract: A compendium of vaporization enthalpies published within the period 1910–2002 is reported. A brief review of temperature adjustments of vaporization enthalpies from temperature of measurement to the standard reference temperature, 298.15 K, is included as are recently suggested reference materials. Vaporization enthalpies are included for organic, organo-metallic, and a few inorganic compounds. This compendium is the third in a series focusing on phase change enthalpies. Previous compendia focused on fusion and sublimation enthalpies. Sufficient data are presently available for many compounds that thermodynamic cycles can be constructed to evaluate the reliability of the measurements. A protocol for doing so is described.
Contributing Partner: UNT College of Arts and Sciences

### Fullerene Coalescence in Nanopeapods: A Path to Novel Tubular Carbon

Date: July 1, 2003
Creator: Hernández, E.; Meunier, Vincent; Smith, B. W.; Rurali, R.; Terrones, Humberto; Buongiorno Nardelli, Marco et al.
Description: Article on fullerene coalescence in nanopeapods. Abstract: A fascinating structural transformation occurring inside single-walled carbon nanotubes (SWNTs) is the fullerene coalescence, which is responsible for forming stable zeppelinlike carbon molecules. We report in situ transmission electron microscope (TEM) observations revealing sequences of fullerene coalescence induced by electron irradiation on pristine nanotube peapods, together with extensive theoretical investigations of the microscopic mechanism underlying this process. TEM images indicate that the merging of fullerenes results in stable but corrugated tubules (5 to 7 Å in diameter) confined within SWNTs. These observations have been confirmed using a combination of theoretical approaches based on molecular dynamics, empirical potentials, tight-binding methods, Monte Carlo techniques, and first principles calculations. We have fully elucidated the coalescence mechanism of fullerenes inside SWNTs under electron irradiation and thermal annealing. The process occurs via the polymerization of C₆₀ molecules followed by surface reconstruction, which can be triggered either by the formation of vacancies (created under electron irradiation) or by surface-energy minimization activated by thermal annealing. These novel tubular forms of carbon contain hexagons, pentagons, heptagons, and octagons. The stability, electronic properties, and electron conductance of the novel tubules are strongly affected by the final geometry of the coalesced fullerene complex. ...
Contributing Partner: UNT College of Arts and Sciences

### Functional and Phylogenetic Analyses of a Conserved Regulatory Program in the Phloem of Minor Veins

Date: November 2003
Creator: Ayre, Brian G.; Blair, Jaime E. & Turgeon, Robert
Description: This article discusses functional and phylogenetic analyses of a conserved regulatory program in the phloem of minor veins, which are developmentally and physiologically distinct from the phloem in the rest of the vascular system.
Contributing Partner: UNT College of Arts and Sciences

### Generalized Master Equation Via Aging Continuous-Time Random Walks

Date: 2003
Creator: Allegrini, Paolo; Aquino, Gerardo; Grigolini, Paolo; Palatella, Luigi & Rosa, Angelo
Description: This article discusses the problem of the equivalence between continuous-time random walk (CTRW) and generalized master equation (GME).
Contributing Partner: UNT College of Arts and Sciences

### In the search for the low-complexity sequences in prokaryotic and eukaryotic genomes: how to derive a coherent picture from global and local entropy measures

Date: 2003
Creator: Acquisti, Claudia; Allegrini, Paolo; Bogani, Patrizia; Buiatti, Marcello, 1937-; Catanese, Elena; Fronzoni, Leone et al.
Description: Paper discussing the search for the low-complexity sequences in prokaryotic and eukaryotic genomes and how to derive a coherent picture from global and local entropy measures. Abstract: We investigate on a possible way to connect the presence of Low-Complexity Sequences (LCS) in DNA genomes and the nonstationary properties of base correlations. Under the hypothesis that these variations signal a change in the DNA function, we use a new technique, called Non-Stationarity Entropic Index (NSEI) method, and we prove that this technique is an efficient way to detect functional changes with respect to a random baseline. The remarkable aspect is that NSEI does not imply any training data or fitting parameter, the only arbitrarity being the choice of a marker in the sequence. We make this choice on the basis of biological information about LCS distributions in genomes. We show that there exists a correlation between changing the amount in LCS and the ration of long-to short-range correlation.
Contributing Partner: UNT College of Arts and Sciences

### Jahn - Teller Distortion in the Phosphorescent Excited State of Three-Coordinate Au(I) Phosphine Complexes

Date: November 4, 2003
Creator: Barakat, Khaldoon A.; Cundari, Thomas R., 1964- & Omary, Mohammad A.
Description: This article discusses three-coordinate Au(I) phosphine complexes. Abstract: DFT calculations were used to optimize the phosphorescent excited state of three-coordinate [Au(PR3)3]+ complexes. The results indicate that the complexes rearrange from their singlet ground-state trigonal planar geometry to a T-shape in the lowest triplet luminescent excited state. The optimized structure of the exciton contradicts the structure predicted based on the AuP bonding properties of the ground-state HOMO and LUMO. The rearrangement to T-shape is a Jahn-Teller distortion because an electron is taken from the degenerate e' (5dxy, 5dx2-y2) orbital upon photoexcitation of the ground-state D3h complex. The calculated UV absorption and visible emission energies are consistent with the experimental data and explain the large Stokes' shifts while such correlations are not possible in optimized models that constrained the exciton to the ground-state trigonal geometry.
Contributing Partner: UNT College of Arts and Sciences
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