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3-Center-4-Electron Bonding in [(silox)2Mo=NtBu]2(μ-Hg) Controls Reactivity while Frontier Orbitals Permit a Dimolybdenum π-Bond Energy Estimate
This article discusses 3-center-4-electron bonding. Abstract: Na/Hg reduction of (silox)2Cl2Mo=NtBu (3) afforded C2h [(silox)2Mo=NtBu]2(μ-Hg) (12-Hg), which consists of two distorted trigonal monoprisms with Hg at the each apex (d(MoHg) = 2.6810(5)Å). Calculations reveal 3c4e bonding in the linear MoHgMo linkage that renders 12-Hg susceptible to nucleophilic cleavage. Exposure to PMe3 and pyridine rapidly (<5 min) affords (silox)2(tBuN)MoLn (L = PMe3, n = 1 (1-PMe3); py, n = 2 (1-py2)), while poorer nucleophiles (L = C2H4, 2-butyne) yield adducts (e.g., 1-C2H4 and 1-C2Me2) after prolonged heating. The HOMO and LUMO of 12-Hg are "stretched" π and π* orbitals from which four states arise: 1Ag (GS), 3Bu, 1Bu, and 1Ag. ∆E = E(1Bu) - E(3Bu) = 2K, where K is the exchange energy. Magnetic studies indicate E(3Bu) - E(1Ag) ≈ 550 cm-1 (calcd 1744 cm-1), and a UV-vis absorption at 10 000 cm-1 is assigned to 1Ag → 1Bu, permitting K to be evaluated as 4725 cm-1. With the π → π* transition in Schrock's [Mo(NAr)(CH2tBu)(OC6F5)]2 (4) assigned at 528 nm, this estimation places its π-bond energy as {E(π2 → π-1 → π*1 in 4) - E(1Ag → 1Bu in 12-Hg)} + E(1Ag → 3Bu in 12-Hg) = 27 kcal/mol. digital.library.unt.edu/ark:/67531/metadc77136/
₁¹H+ - and ₂⁴He+ - induced M-shell x-ray-production cross sections for selected elements in the rare-earth region
This article discusses ₁¹H+ - and ₂⁴He+ -induced M-shell x-ray production cross sections for selected elements in the rare-earth region. Abstract: The measurements of M-shell x-ray-production cross sections induced by ₁¹H+ and ₂⁴He+ ions are compared to the first-Born-approximation and ECPSSR (energy loss, Coulomb-deflection effects; perturbed-stationary-state approximation, with relativistic corrections) theories. Most of the reported experimental data were measured in the authors' laboratory and the other measurements were taken from the literature. The data from the authors' laboratory were for incident H+ and He+ ions in the energy range from 0.25 to 2.5 MeV. The M-shell x-ray-production cross sections were measured for the following thin targets: 59Pr, 60Nd, 63Eu, 64Gd, 66Dy, 67Ho, 68Er, 70Yb, and 72Hf. The data were for the following elements: 54Xe, 59Pr, 60Nd, 62Sm, 63Eu, 64Gd, 65Tb, 66Dy, 67Ho, 68Er, 70Yb, 72Hf, 73Ta, 74W, 78Pt, 79Au, 80Hg, 82Pb, 83Bi, and 92U. The first-born-approximation calculations of the ionization cross section were made using the plane-wave Born approximation for direct ionization and the Oppenheimer-Brinkman-Kramers approximation of Nikolaev for electron capture. The ECPSSR theory of Brandt and Lapicki [Phys. Rev. A 23, 1717 (1981)] goes beyond the first Born approximation and accounts for the energy loss, Coulomb deflection, and relativistic effects in the perturbed-stationary-state theory. The first Born approximation overpredicts all measurements. The ECPSSR theory predicts the M-shell production cross sections correctly for Z2 > 70 and energies per μ > 0.25 MeV/μ. In the rare-earth region the ECPSSR results lie above the data at higher projectile energies and fall off below the data at lower energies. digital.library.unt.edu/ark:/67531/metadc139491/
The 2011 Beta Eta Spring Banquet. Celebration of Rediscovery of the Elements
Article describing an Eta Beta celebration of the completion of James and Virginia Marshall's "Rediscovery of the Elements." Photographs from the event are included. Three separate articles appear on the right side of the page. digital.library.unt.edu/ark:/67531/metadc111260/
The 2012 Republican Primaries
This presentation is part of the faculty lecture series UNT Speaks Out on the 2012 Presidential Primaries. In this presentation, the author gives the audience an overview of the structure of the primaries, and provides a recap of past primaries. The author also speaks about the money, momentum, and media attention in the primaries. digital.library.unt.edu/ark:/67531/metadc83792/
Abraham model correlations for solute partitioning into o-xylene, m-xylene and p-xylene from both water and the gas phase
This article discusses Abraham model correlations for solute partitioning into o-xylene, m-xylene and p-xylene from both water and the gas phase. Abstract: Experimental data have been compiled from the publisher literature on the partition coefficients of solutes and vapors into o-xylene, m-xylene and p-xylene at 298 K. The logarithms of the water-to-xylene partition coefficients, log P, and gas-to-xylene partition coefficients, log K, were correlated with the Abraham solvation parameter model. The derived mathematical expressions described the observed log P and log K data for the three xylene isomers to within average deviations of 0.14 log units or less. digital.library.unt.edu/ark:/67531/metadc155635/
Abraham Model Correlations for Transfer of Neutral Molecules and Ions to Sulfolane
This article discusses Abraham model correlations for the transfer of neutral molecules and ions to sulfolane. Data have been compiled from the published literature on the partition coefficients of solutes and vapors into anhydrous sulfolane. The logarithms of the water-to-sulfolane partition coefficients, log P, and gas-to-sulfolane partition coefficients, log K, were correlated with the Abraham solvation parameter model. The derived correlations described the observed log P and log K values for solutes dissolved in sulfolane to within average standard deviations of 0.14 log units or less. The log P correlation was extended to include the partition of ions by inclusion of a cation-solvent and an anion-solvent term. digital.library.unt.edu/ark:/67531/metadc157293/
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/
An Abstract Index Theorem on Non-Compact Riemannian Manifolds
This article discusses an abstract index theorem on non-compact Riemannian manifolds. Abstract: We prove an abstract index theorem for essentially self-adjoint Fredholm supersymmetric first-order elliptic differential operators on Hermitian vector bundles over complete oriented Riemannian manifolds. According to our main result the supersymmetric L2-index of such an operator can be expressed as the sum of a "local contribution" (the familiar Atiyah-Singer index form, suitably restricted to and integrated over a finite region) and a "boundary contribution" (which depends only on the restriction of the operator at large distances). This is done by splicing together local parametrices and Green's operators defined "at infinity". The result yields (in fact is equivalent to) a generalisation of the relative index theorem of Gromov and Lawson. digital.library.unt.edu/ark:/67531/metadc159527/
Accountable Science: The COMPETES Act Needs to Demonstrate an Accountability Attitude
This article discusses the U.S. National Science Foundation's (NSF) Broader Impacts Merit Review Criterion in relation to the America COMPETES Reauthorization Act of 2010. digital.library.unt.edu/ark:/67531/metadc86163/
Accurate Enthalpies of Formation of Alkali and Alkaline Earth Metal Oxides and Hydroxides: Assessment of the Correlation Consistent Composite Approach (ccCA)
This article discusses accurate enthalpies of formation of alkali and alkaline earth metal oxides and hydroxides. Abstract: Computing the enthalpies of formation for alkali metal and alkaline earth metal oxides (MₓO) and hydroxides [M(OH)n] using the Gaussian-n (Gn) and Weismann-n (Wn) ab initio model chemistries is difficult due to an improper treatment of core-valence electron correlation effects. Using a new model chemistry called the correlation consistent Composite Approach (ccCA), enthalpies of formation were determined for eight different alkali/alkaline earth metal oxides and hydroxides. Unlike the Gn and Wn model chemistries, which must be modified to properly account for core-valence electron correlation, the standard implementations of the ccCA provide acceptable results, and all enthalpies of formation obtained with the ccCA are within the accepted range of recommended values. digital.library.unt.edu/ark:/67531/metadc77173/
Activation of Carbon-Hydrogen and Hydrogen-Hydrogen Bonds by Copper-Nitrenes: A Comparison of Density Functionality Theory with Single- and Multireference Correlation Consistent Composite Approaches
This article discusses a comparison of density functional theory with single- and multireference correlation consistent composite approaches. Abstract: The kinetics and thermodynamics of copper-mediated nitrene insertion into C-H and H-H bonds (the former of methane) have been studied using several levels of theory: B3LYP/6-311++G(d,p), B97-1/cc-pVTZ, PBE1KCIS/cc-pVTZ, and ccCA (correlation consistent Composite Approach). The results show no significant difference among the DFT methods. All three DFT methods predict the ground state of the copper-nitrene model complex, L'Cu(NH), to be a triplet, while single reference ccCA predicts the singlet to be the ground state. The contributions to the total ccCA energy indicate that the singlet state is favored at the MP2/CBS level of theory, while electron correlation beyond this level (CCSD(T)) favors a triplet state, resulting in a close energetic balance between the two states. A multireference ccCA method is applied to the nitrene active species and supports the assignment of a singlet ground state. In general, the largest difference in the model reaction cycles between DFT and ccCA methods is for processes involving radicals and bond dissociation. digital.library.unt.edu/ark:/67531/metadc107767/
Activation of Carbon-Hydrogen Bonds via 1,2-Addition across M-X (X = OH or NH2) Bonds of d6 Transition Metals as a Potential Key Step in Hydrocarbon Functionalization: A Computational Study
This article discusses the activation of carbon-hydrogen bonds. Abstract: Recent reports of 1,2-addition of C-H bonds across Ru-X(X = amido, hydroxo) bonds of TpRu-(PMe₃)X fragments {Tp = hydridotris(pyrazolyl)borate} suggest opportunities for the development of new catalytic cycles for hydrocarbon functionalization. In order to enhance understanding of these transformations, computational examinations of the efficacy of model d6 transition metal complexes of the form [(Tab)M-(PH3)2X]q (Tab = tris-azo-borate; X = OH, NH2; q = -1 to +2; M = Tc(I), Re(I), Ru(II), Co(III), Ir(III), Ni(IV) Pt(IV) for the activation of benzene C-H bonds, as well as the potential for their incorporation into catalytic functionalization cycles, are presented. For the benzene C-H activation reaction steps, kite-shaped transition states were located and found to have relatively little metal-hydrogen interaction. The C-H activation process is best described as a metal-mediated proton transfer in which the metal center and ligand X function as an activating electrophile and intramolecular base, respectively. While the metal plays a primary role in controlling the kinetics and thermodynamics of the reaction coordinate for C-H activation/functionalization, the ligand X also influences the energetics. On the basis of three thermodynamic criteria characterizing salient energetic aspects of the proposed catalytic cycle and the detailed computational studies reported herein, late transition metal complexes (e.g., Pt, Co, etc.) in the d6 electron configuration {especially the TabCo(PH3)2(OH)+ complex and related Co(III) systems} are predicted to be the most promising for further catalyst investigation. digital.library.unt.edu/ark:/67531/metadc77141/
Activation of water on the TiO2 (110) surface: The case of Ti adatoms
This article discusses the activation of water on the TiO2 (110) surface. Abstract: Using first-principles calculations the authors have studied the reactions of water over Ti adatoms on the (110) surface of rutile TiO2. The authors' results provide fundamental insights into the microscopic mechanisms that drive this reaction at the atomic level and assess the possibility of using this system to activate the water dissociation reaction. In particular, the authors show that a single water molecule dissociates exothermically with a small energy barrier of 0.17 eV. After dissociation, both H⁺ and OH⁻ ions bind strongly to the Ti adatom, which serves as an effective reactive center on the TiO2 surface. Finally, clustering of Ti adatoms does not improve the redox activity of the system and results in a slightly higher energy barrier for water dissociation. digital.library.unt.edu/ark:/67531/metadc132989/
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/
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/
Analytical solutions for a two-level system driven by a class of chirped pulses
In this article, the authors present analytical solutions for the problem of a two-level atom driven by a class of chirped pulses. The solutions are given in terms of Heun functions. By use of the appropriate chirping parameters, an enhancement of four orders of magnitude in the population transfer is obtained. digital.library.unt.edu/ark:/67531/metadc103257/
Analyzing How Business Students Engage in Learning in an Introductory Data Analysis Course
This poster discusses an analysis of how business students engage in learning in an introductory data analysis course. A variety of pedagogical activities are used in this introductory data analysis course for business students. In fall of 2012, students were able to score points on each of the following activities: experiential group projects, clicker questions, learning modules, online post chapter quizzes, in class exams, and extra credit questions. An analysis was performed to determine how these activities relate to each other and to improvement in student grades. digital.library.unt.edu/ark:/67531/metadc157295/
L- and M-shell x-ray production cross sections of Nd, Gd, Ho, Yb, Au, and Pb by 25-MeV carbon and 32-MeV oxygen ions
This article discusses L- and M-shell x-ray production. Abstract: L- and M-shell x-ray production cross sections have been measured for thin solid targets of neodymium, gadolinium, holmium, ytterbium, gold and lead by 25-MeV ₆¹²C(q)+ (q=4,5,6) and by 32-MeV ₈¹⁶O(q)+ (q=5,7,8). The cross sections were determined from measurements made with thin targets (less than 2.25 μg/cm2). For projectiles with one or two K-shell vacancies, the target x-ray production cross sections were found to be enhanced over those for projectiles without a K-shell vacancy. The sum of direct ionization to the continuum (DI) plus electron capture (EC) to the L,M,N,... shells and EC to the K shell of the projectile have been extracted from the data. The results are compared to the predictions of first Born theories, i.e., plane-wave Born approximation for DI and Oppenheimer-Brinkman-Kramers formula of Nikolaev for EC, and to the ECPSSR that accounts for energy loss and Coulomb deflection of the projectile as well as for relativistic and perturbed stationary states of inner-shell electrons. digital.library.unt.edu/ark:/67531/metadc139494/
Annual Variation of Abundance and Composition in Forest Bird Assemblages on Navarino Island, Cape Horn Biosphere Reserve, Chile
This article discusses the annual variation of abundance and composition in forest bird assemblages on Navarino Island, Cape Horn Biosphere Reserve, Chile. Abstract: The structure and dynamics of avian communities in the temperate forests of southern South America have been generally studied during the breeding season (November - March), and reports about seasonal variations and migratory behavior of species are almost lacking. This study examined intra-annual variations on a monthly basis in bird species composition and abundance in the world's southernmost forested ecosystems, found in the Cape Horn Biosphere Reserve, Chile (55°S). Combining data obtained through point-count surveys, mist-netting, and checklist methods, the authors recorded a total of 34 bird species belonging to 20 families. Eighteen of these species were Passeriformes, and the most abundant year-round resident species were Thorn-tailed Rayadito (Aphrastura spinicauda) and Patagonian Sierra-Finch (Phrygilus patagonicus). The most abundant seasonal migrants species were White-crested Elaenia (Elaenia albiceps) and Southern House Wren (Troglodytes musculus). Point-count and mist-netting methods showed a reduction in species richness and abundance during winter, with one third of the bird assemblage absent. This proportion was lower than that documented for more northern Nothofagus forests. Additionally, the authors' data provided no evidence that intra-annual patterns of avian community structure were significantly affected by a recently implemented tourism trail through the Omora Park. The authors believe that understanding seasonal patterns of richness, abundance, and migratory status of Chilean temperate forests birds will help to better understand the world's southernmost forest ecosystem, implement effective conservation, facilitate sustainable ecotourism, and lead to new ecological and evolutionary research. digital.library.unt.edu/ark:/67531/metadc97951/
Anomalous diffusion and ballistic peaks: A quantum perspective
This article discusses anomalous diffusion and ballistic peaks. Abstract: The quantum kicked rotor and the classical kicked rotor are both shown to have truncated Lévy distributions in momentum space, when the classical phase space has accelerator modes embedded in a chaotic sea. The survival probability for classical particles at the interface of an accelerator mode and the chaotic sea has an inverse power-law structure, whereas that for quantum particles has a periodically modulated inverse power law, with the period of oscillation being dependent on Planck's constant. These logarithmic oscillations are a renormalization group property that disappears as ħ → 0 in agreement with the correspondence principle. digital.library.unt.edu/ark:/67531/metadc75417/
Anomalous diffusion and environment-induced quantum decoherence
This article discusses anomalous diffusion and environment-induced quantum decoherence. Abstract: We study the anomalous diffusion resulting from the standard map in the so-called accelerating state, and we observe that it is determined by unusually large times of sojourn of the classical trajectories in the fractal region at the border between the chaotic sea and the acceleration island. The quantum-mechanical breakdown of this property implies a coherence among so slightly different values of momentum as to become much more robust against environment fluctuations than the quantum localization corresponding to normal diffusion. digital.library.unt.edu/ark:/67531/metadc139477/
Anomalous diffusion associated with nonlinear fractional derivative Fokker-Planck-like equation: Exact time-dependent solutions
This article discusses anomalous diffusion associated with nonlinear fractional derivative Fokker-Planck-like equation. Abstract: We consider the d=1 nonlinear Fokker-Planck-like equation with fractional derivatives (∂/∂t)P(x,t) = D(∂ƴ/∂xƴ)[P(x,t]v. Exact time-dependent solutions are found for v = (2 - y)/(1 + y)(-∞ < y ⩽ 2). By considering the long-distance asymptotic behavior of these solutions, a connection is established, namely, q = (y + 3)/(Y + 1)(0 < y ⩽ 2), with the solutions optimizing the nonextensive entropy characterized by index q. Interestingly enough, this relation coincides with the only already known for Lévy-like superdiffusion (i.e., v = 1 and 0 < y ⩽ 2). Finally, for (y,v) = (2,0) the authors obtain q=5/3, which differs from the value q = 2 corresponding to the y = 2 solutions available in the literature (v < 1 porous medium equation), thus exhibiting nonuniform convergence. digital.library.unt.edu/ark:/67531/metadc77162/
Application of the Correlation Consistent Composite Approach (ccCA) to Third-Row (Ga-Kr) Molecules
This article discusses the application of the correlation consistent composite approach (ccCA). Abstract: The correlation consistent composite approach (ccCA) has been applied to the G3/05 training set of 51 energetic properties for the atoms and molecules that contain the 4p elements, Ga-Kr. When atomic and molecular first-order spin orbit coupling corrections are added to open shell atoms and molecules, the ccCA has a mean absolute deviation from experiment (MAD) of 0.95 kcal mol-1, an improvement of 0.10 kcal mol-1 over G3 and G3X model chemistries. The performance of the ccCA on third-row-containing atoms and molecules is, therefore, commensurate in accuracy with previous studies on lighter main group elements H-Ar. While the typical methods used to compute theoretical molecular spin orbit corrections may go against the spirit of "black box" model chemistries, such corrections may be necessary for molecules containing heavy elements such as Ga-Kr. For example, when second-order spin orbit corrections are added to the atomic and molecular energies, the ccCA MAD is reduced to 0.88 kcal mol-1. digital.library.unt.edu/ark:/67531/metadc75422/
Are Net Discount Rates Stationary?: Some Further Evidence
This article discusses net discount rates. Abstract: Gamber and Sorensen provide evidence suggesting that the net discount ratio experienced a level shift in the mean between 1977 and 1981. If such a shift occurred, the nonlinearity in the data shows up as a failure to reject the null hypothesis that a unit root is present; that is, the series is I(1). In this reply, evidence is presented - the Phillips-Perron test and a univariate version of the Stock-Watson q-test - suggesting that the net discount ratio is stationary. Hence, the mean is constant. In addition, if one extends the analysis to include the 1989 through 1993 period, the net discount ratio appears to be reverting. digital.library.unt.edu/ark:/67531/metadc71791/
Are Net Discount Ratios Stationary?: The Implications For Present Value Calculations
Abstract: This article analyzes the relationship between real interest rates and real growth rates in wages. The stationary of these time series has been discussed in the literature. However, since the net discount ratio, (1 + gτ)/(1 + rτ), is a nonlinear transformation, it is not necessarily stationary even if the interest rate and growth rate in wages series are each stationary. On the other hand, the net discount ratio may be stationary even if the interest rate and growth rate series are both non-stationary. The significant finding of this article is that this ratio is stationary. This conclusion appears robust since it holds for at least four different Treasury securities analyzed: three month, six month, one year, and three year. Therefore, a real net discount ratio, (1 + gτ)/(1 + rτ), can be used with confidence in constructing present value forecasts of expected earnings. digital.library.unt.edu/ark:/67531/metadc71790/
Aromatic C-H Activation and Catalytic Hydrophenylation of Ethylene by TpRu{P(OCH2)3CEt} (NCMe)Ph
This article discusses aromatic C-H activation and catalytic hydrophenylation of ethylene by TpRu{P(OCH2)3CEt} (NCMe)Ph. Abstract: The complexes TpRu{P(OCH2)3CEt}(L)R {L = PPh3 or NCMe; R = Cl, OTf (OTf = trifluoromethane-sulfonate), or Ph; Tp = hydridotris(pyrazolyl)borate} and TpRu{P(OCH2)3CEt} (ɳ3-C3H4Me) were synthesized and isolated. TpRu{P(OCH2)3CEt} (NCMe)Ph was found to initiate C-H activation of benzene and to catalyze the hydrophenylation of ethylene to produce ethylbenzene. Ethylene C-H activation to ultimately produce TpRu{P(OCH2)3CEt} (ɳ3-C3H4Me) kinetically competes with the catalytic hydrophenylation of ethylene. Computational studies were undertaken on reactions in the proposed catalytic ethylene hydrophenylation cycle as well as key side reactions. digital.library.unt.edu/ark:/67531/metadc77190/
Arylpalladium Phosphonate Complexes as Reactive Intermediates in Phosphorus-Carbon Bond Forming Reactions
This article discusses arylpalladium phosphonate complexes as reactive intermediates in phosphorus-carbon bond forming reactions. Abstract: Phosphorus-carbon bond formation from discrete transition metal complexes have been investigated through a combination of synthetic, spectroscopic, crystallographic, and computational methods. Reactive intermediates of the type (diphosphine)Pd(aryl)P(O)(OEt)2) have been prepared, characterized, and studied as possible intermediates in metal-mediated coupling reactions. Several of the reactive intermediates were characterized crystallographically, and a discussion of the solid state structures is presented. In contrast to other carbon-heteroelement bond forming reactions, palladium complexes containing electron-donating substituents on the aromatic fragment exhibited faster rates of reductive elimination. Large bit angle diphosphine ligands induced rapid rates of elimination, while bipyridine and small bite angle diphosphine ligands resulted in much slower rates of elimination. An investigation of the effect of typical impurities on the elimination reaction was carried out. While excess diphosphine, pyridine, and acetonitrile had little effect on the observed rate, the addition of water slowed the phosphorus-carbon bond forming reaction. Coordination of water to the complex was observed spectroscopically and crystallographically. Computational studies were utilized to probe the reaction pathways for P-C bond formation via Pd catalysis. digital.library.unt.edu/ark:/67531/metadc77191/
Atomic resolution ultrahigh vacuum scanning tunneling microscopy of epitaxial diamond (100) films
In this article, the authors report atomic resolution images of chemical vapor deposition grown epitaxial diamond (100) films obtained in ultrahigh vacuum (UHV) with a scanning tunneling microscope. A (2X1) dimer surface reconstruction and amorphous atomic regions are observed. The (2X1) unit cell is measured to be 0.51±0.01X0.25±0.01 nm2. The amorphous regions are identified as carbon. A radial structure 1.5 nm in diameter is observed on a plane at a 20° slope to the (2X1) surface. Tunneling current versus voltage spectra in UHV and Raman spectra are also obtained. digital.library.unt.edu/ark:/67531/metadc84147/
Atomic structure of steps and defects on the clean diamond (100)-2 X 1 surface studied using ultrahigh vacuum scanning tunneling microscopy
In this article, the authors report ultrahigh vacuum scanning tunneling microscopy studies of the clean nonhydrogen-terminated diamond (100)-2 X 1 surface showing single- and double-layer steps that are rebonded. The main defects observed are single, multiple, and row dimer vacancies, and antiphase boundaries. Buckling of dimers is not observed, consistent with symmetric dimers. digital.library.unt.edu/ark:/67531/metadc83794/
The Autecology of the Fío-Fío (Elaenia Albiceps Lafresnaye and D'Orbigny) in Subantarctic Forests of the Cape Horn Biosphere Reserve, Chile
This article discusses the autecology of the fío-fío. Abstract: As the most diverse and abundant terrestrial vertebrates in the Cape Horn Archipelago, birds potentially play key roles in the ecology of subantarctic ecosystems. However, the lack of long-term ornithological studies in southern South America has previously hindered the identification of relevant aspects of the autecology of even the most common species. One abundant species in the austral summer is the fío-fío's ecology in the CHBR by determining: a) longevity and site fidelity, b) arrival-departure dates, c) abundance of adults and juveniles, d) diet and e) morphology. A total 827 fío-fíos were banded during the study period. Of the 67 recaptures, it was possible to determine that fío-fíos may live at least up to 7 years. Fío-fíos arrived as early as 28 October and left as late as 15 April with juveniles fledging in January. In the austral archipelago, the fío-fío's diet consisted of 10 invertebrate orders and at least 5 plant species. Males had significantly longer tails and wings than females, while females were significantly heavier in the pre-fledging season (Oct-Dec). This study provides new information on the autecology of fío-fío in the world's southernmost forests. digital.library.unt.edu/ark:/67531/metadc97944/
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/
Bianucci, Mannella, and Grigolini Reply
This article is a reply to a comment by Massimo Falcioni and Angelo Vulpiani. In a previous letter, the authors have discussed the linear response theory (LRT) and shown that the breakdown of this theory occurring at intermediate times, observed in an earlier paper [2] as well as in [1], disappears upon an increase of the number of degrees of freedom. In a comment to [1] Falcioni and Vulpiani [3] claim that this breakdown is rather a consequence of the lack of mixing: according to them, regardless of the number of degrees of freedom, mixing is the key ingredient behind the LRT. digital.library.unt.edu/ark:/67531/metadc77166/
Bieberians at the Gate?
In this article, the authors discuss the idea that non-philosophers should judge philosophers. As universities face growing demands for academic accountability, philosophers ought to take the lead in exploring what accountability means. Otherwise we may be stuck with Dickens's Mr. Gradgrind. ("Now, what I want is Facts. Teach these boys and girls nothing but Facts. Facts along are wanted in life.") But a philosophical account of accountability will also require redefining the boundaries of what counts as philosophy. digital.library.unt.edu/ark:/67531/metadc130189/
Biocultural conservation in Cape Horn: the Magellanic woodpecker as a charismatic species
This book chapter discusses a research project to promote biocultural conservation in Cape Horn, Chile. At the southernmost tip of the Americas, the Cape Horn Biosphere Reserve (CHBR) encompasses one of the world's most pristine remaining wilderness areas and is home to the indigenous Yaghan (or Yamana) community, which featured prominently in Charles Darwin's 'Voyage of the Beagle'. Its remoteness and uniqueness, however, are threatened by the introduction of exotic species such as the North American beaver and American mink, increasing development pressures from new connectivity, resource exploitation, and the development of tourism. To implement the biosphere reserve and conserve its natural and cultural richness requires the active participation of the community, as well as linkages and integration between various disciplines and institutions. In an effort to achieve the goal of transdisciplinary integration, the authors used the strategy of identifying a charismatic species, since doing so serves to motivate people towards biodiversity conservation, to communicate ecological concepts, and to integrate both the ecological and social dimensions of sustainability. This study was developed together with the population of Puerto Williams, a town with 2200 inhabitants located on Navarino Island, and the largest human settlement within the CHBR. digital.library.unt.edu/ark:/67531/metadc97940/
Biocultural Ethics: Recovering the Vital Links between the Inhabitants, Their Habits, and Habitats
This article discusses biocultural ethics. Abstract: Biocultural homogenization involves three major drivers: (a) the physical barrier to everyday contact with biodiversity derived from the rapid growth of urban population, (b) the conceptual barrier derived from the omission in formal and non-formal education of native languages that contain a broad spectrum of traditional ecological knowledge and values, and (c) political barriers associated with the elimination or reduction of the teaching of ethics under the prevailing neoliberal economy governance since the 1960s. Biocultural ethics aims at overcoming these barriers by recovering the vital links between biological and cultural diversity, between the habits and the habitats of the inhabitants. These links are acknowledged by early Western philosophy. Amerindian traditional ecological knowledge, and contemporary ecological and evolutionary sciences, but have been lost in prevailing modern ethics. There is an overlooked diversity of forms of knowing and inhabiting regional ecosystems, each of them having diverse environmental and social consequences. A better understanding of the regionally diverse mosaics of ecosystems, languages, and cultures facilitates the distinction of specific causes and responsible agents of environmental problems, and the disclosure of sustainable practices, forms of ecological knowledge and values that offer already existing options to solve socio-ecological problems. digital.library.unt.edu/ark:/67531/metadc130202/
Biodiversity Of Southernmost Forests And Tundra Ecosystems
This article discusses the biodiversity of southernmost forests and tundra ecosystems. The definition of conservation priorities for biodiversity often focuses only on the numbers of vertebrate animals and seed plants in the northern hemisphere or in the tropics. But what about the other organisms, and the more extreme regions of the world, where the species richness of flowering plants and mammals is low? An interdisciplinary team of US, UK and Chilean taxonomists, ecologists, and philosophers explored the world's southernmost forest and tundra ecosystems to estimate the diversity of the dominant vegetation, namely tiny bryophytes and lichens growing on trees, soils and rocks. digital.library.unt.edu/ark:/67531/metadc132966/
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/
Bonding and Structure of Copper Nitrenes
This article discusses bonding and structure of copper nitrenes. Abstract: Copper nitrenes are of interest as intermediates in the catalytic aziridination of olefins and the amination of C-H bonds. However, despite advances in the isolation and study of late-transition-metal multiply bonded complexes, a bona fide structurally characterized example of a terminal copper nitrene has, to our knowledge, not been reported. In anticipation of such a report, terminal copper nitrenes are studied from a computational perspective. The nitrene complexes studied here are of the form (ß-diketiminate)Cu(NPh). Density functional theory (DFT), complete active space self-consistent-field (CASSCF) electronic structure techniques, and hybrid quantum mechanical/molecular mechanical (QM/MM) methods are employed to study such species. While DFT methods indicate that a triplet (S + 1) is the ground state, CASSCF calculations indicate the a singlet (S = 0) is the ground state, with only a small energy gap between the singlet and triplet. Moreover, the ground-state (open-shell) singlet copper nitrene is found to be highly multiconfigurational (i.e., biradical) and to possess a bent geometry about the nitrene nitrogen, contrasting with the linear nitrene geometry of the triplet copper nitrenes. CASSCF calculations also reveal the existence of a closed-shell singlet state with some degree of multiple bonding character for the copper-nitrene bond. digital.library.unt.edu/ark:/67531/metadc77132/
BOV - a web-based BLAST output visualization tool
This article discusses BOV, a web-based BLAST output visualization tool. Abstract: Background: The BLAST program is one of the most widely used sequence similarity search tools for genomic research, even by those biologists lacking extensive bioinformatics training. As the availability of sequence data increases, more researchers are downloading the BLAST program for local installation and performing larger and more complex tasks, including batch queries. In order to manage and interpret the results of batch queries, a host of software packages have been developed to assist with data management and post-processing. Among these programs, there is almost a complete lack of visualization tools to provide graphic representation of complex BLAST pair-wise alignments. The authors have developed a web-based program, BLAST Output Visualization Tool (BOV), that allows users to interactively visualize the matching regions of query and database hit sequences, thereby allowing the user to quickly and easily dissect complex matching patterns. Results: Users can upload the standard BLAST output in pair-wise alignment format as input to the web server (including batch queries generated installing and running the stand-alone BLAST program on a local server). The program extracts the alignment coordinates of matching regions between the query and the corresponding database hit sequence. The coordinates are used to plot each matching region as colored lines or trapezoids. Using the straightforward control panels throughout the web site, each plotted matching region can be easily explored in detail by, for example, highlighting the region of interest or examining the raw pair-wise sequence alignment. Tutorials are provided at the website to guide users step-by-step through the functional features of BOV. Conclusion: BOV provides a user-friendly web interface to visualize the standard BLAST output for investigating wide-ranging genomic problems, including single query and batch query datasets. In particular, this software is valuable to users interested in identifying regions of co-linearity, duplication, translocation, and inversion among sequences. A web server hosting BOV is accessible via http://bioportal.cgb.indiana.edu/cgi-bin/BOV/index.cgi and the software is freely available for local installations. digital.library.unt.edu/ark:/67531/metadc77114/
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/
Broader Impacts 2.0: Seeing- and Seizing- the Opportunity
This article offers viewpoints on Broader Impacts 2.0. The authors point out that the National Science Board (NSB) has presented us with merit review criteria that challenge us to undertake research that marries scientific merit and broader impacts in a way that benefits the research community, our funding sources, and our society. digital.library.unt.edu/ark:/67531/metadc155643/
Building a Chilean Network for Long-Term Socio-Ecological Research: Advances, perspectives and relevance
This article discusses building a Chilean network for long-term socio-ecological research. Abstract: Since their formal inception in 1980, long-term ecological research (LTER) programs have served as a successful organizing framework to create research agendas and funding mechanisms that allow scientists to address meaningful ecological phenomena at the scales they occur. In its 30 years of existence, LTER has expanded its geographic range (currently the International LTER network has more than 40 country members with sites on every continent) and disciplinary foci (principally encompassing the natural and social sciences and leading some to call for a name change to long-term socio-ecological research efforts exist in both Chile and Argentina, and in 2008, the Institute of Ecology and Biodiversity launched Chile's first concerted effort to link three existing sites (Fray Jorge Forest National Park -33° S, Senda Darwin Biological Station - 43° S, and Omora Ethnobotanical Park - 55° S). Here, the authors present a special feature of the Revista Chilena de Historia Natural, dedicated to LTSER, with the aim of 1) providing a synthesis of some of the most emblematic cases of long-term socio-ecological research in Chile; 2) demonstrating the value of these efforts for the integration of research, education and social outcomes, such as decision making; and 3) offering the perspective of a broad array of participants involved in these initiatives, including graduate students with associated programs from Ibero-America and North America and North America. It is the authors' hope that these compiled works will contribute to the consolidation of the LTSER approach in southern South America both within the academic community and also to better link academia and society. digital.library.unt.edu/ark:/67531/metadc97937/
The Butterfly Dimer [(tBu3SiO)Cr]2 (μ-OSitBu3)2 and Its Oxidative Cleavage to (tBu3SiO)2 Cr(=N-N=CPh2)2 and (tBu3SiO)2 Cr=N(2,6-Ph2-C6H3)
This article discusses the butterfly dimer. Abstract: Treatment of CrCl2(THF)2 with NaOSitBu3 afforded the butterfly dimer [(tBu3SiO)Cr]2 (μ-OSitBu3)2 (1 2), whose d(CrCr) of 2.658(31) Å and magnetism were indicative of strong antiferromagnetic coupling. A Boltzmann distribution of low-energy 1A1, 3B1, 5A1, 7B1, and 9A1 states obtained from calculations on [(HO)2Cr]2(μOH)2 (1'2) were used to provide a reasonable fit of the μeff vs T data. Cleavage of 1 2 with various L (L=4-picoline, p-tolunitrile, tBuCN, tBuNC, Ph2CO, and PMe3) generated (tBu3SiO)2CrL2(1-L2). The dimer was oxidatively severed by Ph2CN2 to give (tBu3SiO)2Cr(N2CPh2)2 (2) and by RN3 at 23 ˚C to afford (silox)2Cr=NR (3-R) for bulky R (adamantyl (Ad), 2,6-iPr2-C6H3, 2,4,6-Me3-C6H2 = Mes, 2,6-Ph2-C6H3) and (tBu3SiO)2Cr(=NR)2 (4-R) for smaller substituents (R = 1-Naph, 2-Anth). X-ray structural studies were conducted on 1 2, square planar 1-(OCPh2)2, pseudo-Td 2 and pseudotrigonal 3-(2,6-Ph2-C6H3), whose S = 1 ground state was discussed on the basis of calculations of (H3SiO)2Cr = NPh (3"-Ph). digital.library.unt.edu/ark:/67531/metadc75425/
C-H Functionalization Reactivity of a Nickel-Imide
This article discusses C-H functionalization reactivity of a Nickel-Imide. Abstract: We report report bifunctional reactivity of the β-diketiminato Ni(III)-imide [Me₃NN]Ni=NAd (1), which undergoes H-atom abstraction (HAA) reactions with benzylic substrates R-H (indane, ethylbenzene, toluene). Nickel-imide 1 competes with the nickel-amide HAA product [Me₃NN]Ni-NHAd (2) for the resulting hydrocarbyl radical R• to give the nickel-amide [Me₃NN]Ni-N(CHMePh)Ad (3) (R-H = ethylbenzene) or aminoalkyl tautomer [Me₃NN]Ni(ɳ²-CH(Ph)NHAd) (4) (R-H = toluene). A significant amount of functionalized amine R-NHAd is observed in the reaction of 1 with indane along with the dinickel imide {[Me₃NN]Ni}₂(μ-NAd) (5). Kinetic and DFT analyses point to rate-limiting HAA from R-H by 1 to give R•, which may add to either imide 1 or amide 2, each featuring significant N-based radical character. Thus, these studies illustrate a fundamental competition possible in C-H amination systems that proceed via a HAA/radical rebound mechanism. digital.library.unt.edu/ark:/67531/metadc107790/
Calculating Changes in Worklife Expectancies and Lost Earnings in Personal Injury Cases
This article discusses calculating changes in worklife expectancies and lost earnings in personal injury cases. Abstract: This paper utilizes the Bureau of Labor Statistics (BLS) new worklife tables' information on workforce participation probabilities to estimate the effect of an injury on a worker's life expectancy, worklife expectancy and discounted expected income. After a medical opinion has been obtained concerning the effect of an injury on a worker's probabilities of living and remaining active, the BLS's probability figures can be adjusted and incorporated into a Markov process to estimate the impact of the injury. It is shown that Alter and Becker's technique can be adapted to estimate the present value of the lost expected income. digital.library.unt.edu/ark:/67531/metadc71789/
Calculation of a Methane C-H Oxidative Addition Trajectory: Comparison to Experiment and Methane Activation by High-Valent Complexes
This article discusses the calculation of a methane C-H oxidative addition trajectory. Abstract: An effective core potential (ECP), parallel supercomputing study of methane activation by 14-electron, Ir(PH₃)₂(X) complexes (X = H, Cl) is presented. Considerable weakening of the coordinated methane C-H bond occurs upon formation of an ɳ²-CH coordinated (X)(PH₃)₂Ir•••HCH₃ adduct. A more strongly bound adduct (with greater weakening of the coordinated C-H bond) occurs when X = Cl versus X = H. The calculated Ir(PH₃)₂(H) + CH₄ → Ir(PH₃)₂(H)₂(Me) reaction enthalpy is -12.8 kcal mol⁻¹, and -41.6 kcal mol⁻¹ for the chloro analogue. The intrinsic reaction coordinate is calculated and compared to an experimental trajectory. Analysis of the wave function along the intrinsic reaction coordinate (IRC) suggests that although donation of electron density from methane to metal is essential for adduct formation, it is not until backdonation to σ* сʜ increases that the C-H bond is activated and cleaved. The electronic and molecular structure of the reacting system along the IRC suggest a two-stage mechanism: substrate to complex donation is important in the early part of the reaction (electrophilic stage) while complex to substrate backdonation is necessary later on (nucleophilic stage) for C-H scission. Finally, comparison of IRCs for low- and high-valent methane-activating complexes shows similar topology in the early portion of the activation event; differentiation between oxidative addition and σ-bond metathesis occurs at the point at which there is a shift from the electrophilic to nucleophilic stage of the reaction. digital.library.unt.edu/ark:/67531/metadc107777/
Calculations of the Relative Energies of the 2B1g and 2A2u States of Cyclobutanetetraone Radical Cation and Radical Anion Provide Further Evidence of a 3B2u Ground State for the Neutral Molecule: A Proposed Experimental Test of the Prediction of a Triplet Ground State for (CO)4
This article discusses ground states. Abstract: B3LYP, CCSD(T), and CASPT2 calculations with the 6-311+G(2df) basis set have been performed on the radical anion and radical cation of cyclobutanetetraone (1). The very similar energies computed for the 2B1g and 2A2u states of both 1·+ and 1·- indicate that the singly occupied b1g and a2u MOs in these two states of the radical cation and anion have nearly the same energies, thus supporting the previously made prediction that neutral 1 has a 3B2u ground state. Reaction of squaric acid with O.(-), followed by negative ion photoelectron spectroscopy (NIPES) on the 1.(-) thus formed, is proposed as an experimental test of the startling prediction that tetraketone (1), a molecule that would be expected to be a closed-shell singlet, actually has a triplet ground state. digital.library.unt.edu/ark:/67531/metadc71812/
Calculations Predict a Large Inverse H/D Kinetic Isotope Effect on the Rate of Tunneling in the Ring Opening of Cyclopropylcarbinyl Radical
This article discusses calculations that predict a large inverse H/D kinetic isotope effect. Abstract: Tunneling rates are expected to decrease exponentially with the square root of the effective tunneling mass. Therefore, on substitution of a heavier for a lighter isotope, the observation of a large kinetic isotope effect (KIE), involving a substantial decrease in rate constant, is a commonly used diagnostic for a large contribution from quantum mechanical tunneling to a reaction. However, in this communication, the authors report the results of calculations that make the opposite prediction about some of the KIEs on the ring opening of cyclopropylcarbinyl radical (1) to 3-butene-1-y1 radical (2) by tunneling at cryogenic temperatures. Substitution of a heavier for a lighter isotope at the radical center (C1) of 1 is calculated to accelerate the rate of tunneling, giving KIEs at this carbon that are inverse. Of particular note is the authors' prediction that substitution of deuterium for both hydrogens at C1 will lead to a nearly 3-fold increase in the rate of reaction at temperatures so low that ring opening proceeds exclusively by tunneling from the lowest vibrational level. digital.library.unt.edu/ark:/67531/metadc71808/
Calculations Predict That Carbon Tunneling Allows the Degenerate Cope Rearrangement of Semibullvalene to Occur Rapidly at Cryogenic Temperatures
This article discusses carbon tunneling. Abstract: Calculations on the role of tunneling in the degenerate Cope rearrangements of semibullvalene (1) and barbaralane (3) predict that, at temperatures below 40 K, tunneling from the lowest vibrational level should make the temperature-independent rate constants k = 1.43 x 10(-3) s(-1) and k = 7.28 x 10(-9) s(-1), respectively. An experiment, using semibullvalene-2(4)-d1, is proposed to test the prediction of rapid tunneling by 1 at cryogenic temperatures. digital.library.unt.edu/ark:/67531/metadc71814/
Canonical and noncanonical equilibrium distribution
This article discusses canonical and noncanonical equilibrium distribution. Abstract: We address the problem of the dynamical foundation of noncanonical equilibrium. We consider, as a source of divergence from ordinary statistical mechanics, the breakdown of the condition of time scale separation between microscopic and macroscopic dynamics. We show that this breakdown has the effect of producing a significant deviation from the canonical prescription. We also show that, while the canonical equilibrium can be reached with no apparent dependence on dynamics, the specific form of noncanonical equilibrium is, in fact, determined by dynamics. We consider the special case where the thermal reservoir driving the system of interest to equilibrium is a generator of intermittent fluctuations. We assess the form of the noncanonical equilibrium reached by the system in this case. Using both theoretical and numerical arguments we demonstrate that Lévy statistics are the best description of the dynamics and that the Lévy distribution is the correct basin of attraction. We show that the correct path to noncanonical equilibrium by means of strictly thermodynamic arguments has not yet been found, and that further research has to be done to establish a connection between dynamics and thermodynamics. digital.library.unt.edu/ark:/67531/metadc77164/
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