Revisiting point defects in ionic solids and semiconductors

The study of point defects in non-metallic crystals has become relevant for an increasing number of materials applications. Progress requires a foundation of consistent definitions and terminology. This Comment clarifies the underlying definitions of point defects, encourages the correct use of relative charge for their description and emphasizes their recognition as quasiparticles

Non-relativistic quantum scattering from non-local separable potentials: the eigenchannel approach

A recently formulated version of the eigenchannel method [R. Szmytkowski, Ann. Phys. (N.Y.) {\bf 311}, 503 (2004)] is applied to quantum scattering of Schr\"odinger particles from non-local separable potentials. Eigenchannel vectors and negative cotangents of eigenphase-shifts are introduced as eigensolutions to some weighted matrix spectral problem, without a necessity of prior construction and diagonalization of the scattering matrix. Explicit expressions for the scattering amplitude, the total cross section in terms of the eigenchannel vectors and the eigenphase-shifts are derived. An illustrative example is provided.Comment: 10 pages, slightly improved versio

Effects of Dust Scattering in Expanding Spherical Nebulae

The mean intensity of planetary nebulae with an expanding atmosphere is modeled by considering dusty and dust-free atmospheres. The bulk matter density is determined from the adopted velocity field through the equation of continuity. The gas is assumed to consist of hydrogen and helium and the gas-to-dust mass ratio is taken to be $3\times10^{-4}$. The Rayleigh phase function is employed for atomic scattering while the full Mie theory of scattering is incorporated for determining the dust scattering and absorption cross-section as well as the phase function for the angular distribution of photons after scattering. It is shown that in a dust free atmosphere, the mean intensity increases with the increase in the expansion velocity that makes the medium diluted. The mean intensity profile changes significantly when dust scattering is incorporated. The increase in forward scattering of photons by the dust particles yields into an increase in the mean intensity as compared to that without dust. The mean intensity increases as the particle size is increased. Thus it is shown that both the expansion of the medium and the presence of dust play important role in determining the mean intensity of a planetary nebulae.Comment: 18 pages, Elseveir style (cls file included), 5 postscript figures, Accepted for publication in New Astronom

Thermal degradation and isomerisation kinetics of triolein studied by infrared spectrometry and GC-MS combined with chemometrics

Triolein, a triglyceride containing oleic acid as the only acid moiety in the glyceride molecules has been isothermally treated at 280,300,and 325 degrees C in glass vials under nitrogen atmosphere. The products formed during the thermal treatment at each temperature have been analysed both by infrared spectrometry and GC-MS. The CC-MS analysis was performed after derivatisation of the fatty acids into their methyl esters (FAMEs). Chemometric tools were used in determining the concentrations of the main products namely triolein and trieaidin in the thermally treated mixtures. The concentration profiles of the trielaidin formed during thermal treatment at the above three temperatures were used in determining activation energy for the cis-trans isomerisation of triolein. The combined analysis reveals that the thermal treatment induces not only cis-trans isomerisation but also fission and fusion in the molecules. Furthermore, migration of the double bond in oleic and elaidic acids forming cis and trans isomers of the 18:1 acid was also observed. The heat-induced isomerisation in triolein follows a zeroth order reaction with an activation energy 41 +/- 5 kcal/mol. (c) 2008 Elsevier Ireland Ltd. All rights reserve

Instantons, the QCD Vacuum, and Hadronic Physics

A large body of evidence from lattice calculations indicates that instantons play a major role in the physics of light hadrons. This evidence is summarized, and recent results concerning the instanton content of the SU(3) vacuum, instanton contributions to the static potential, and a new class of instanton solutions at finite temperature are reviewed.Comment: 13 pages, 8 figures, Latex using Boxed EPS Macros, LATTICE98 Plenary Tal

A semiclassical trace formula for the canonical partition function of one dimensional systems

We present a semiclassical trace formula for the canonical partition function of arbitrary one-dimensional systems. The approximation is obtained via the stationary exponent method applied to the phase-space integration of the density operator in the coherent state representation. The formalism is valid in the low temperature limit, presenting accurate results in this regime. As illustrations we consider a quartic Hamiltonian that cannot be split into kinetic and potential parts, and a system with two local minima. Applications to spin systems are also presented.Comment: 22 pages, 4 figures new section with applications to spin system

Stories from the field: Most Significant Change (MSC) synthesis

In January of 2007, a number of people working with the CGIAR Challenge Program on Water and Food (CPWF) were invited to tell stories about the “most significant change” (MSC) they had observed as a result of CPWF activity. They were guided by two questions, posed to establish the stories’ domain and time frame of interest. These were: “What has been the most significant technical development/advance made by your CPWF project / theme / basin since the start?” “What has been the most significant partnership change (significant in terms of making scientific progress and/or developmental impact more likely) that has taken place since the start of your CPWF project (or theme or basin)?” This paper aims to pull together some of the threads emerging from these stories, weaving them into a fabric that gives insight into CPWF approaches and achievements

Scattering of Dirac particles from non-local separable potentials: the eigenchannel approach

An application of the new formulation of the eigenchannel method [R. Szmytkowski, Ann. Phys. (N.Y.) {\bf 311}, 503 (2004)] to quantum scattering of Dirac particles from non-local separable potentials is presented. Eigenchannel vectors, related directly to eigenchannels, are defined as eigenvectors of a certain weighted eigenvalue problem. Moreover, negative cotangents of eigenphase-shifts are introduced as eigenvalues of that spectral problem. Eigenchannel spinor as well as bispinor harmonics are expressed throughout the eigenchannel vectors. Finally, the expressions for the bispinor as well as matrix scattering amplitudes and total cross section are derived in terms of eigenchannels and eigenphase-shifts. An illustrative example is also provided.Comment: Revtex, 9 pages, 4 figures, published versio

Tau Protein Hyperphosphorylation and Aggregation in Alzheimer’s Disease and Other Tauopathies, and Possible Neuroprotective Strategies

Acknowledgments This work was supported by The Croatian Science Foundation grant No. IP-2014-09-9730 (“Tau protein hyperphosphorylation, aggregation, and trans-synaptic transfer in Alzheimer’s disease: cerebrospinal fluid analysis and assessment of potential neuroprotective compounds”) and European Cooperation in Science and Technology (COST) Action CM1103 (“Stucture-based drug design for diagnosis and treatment of neurological diseases: dissecting and modulating complex function in the monoaminergic systems of the brain”). PRH is supported in part by NIH grant P50 AG005138. We also thank Mate Babić for help in preparation of schematics.Peer reviewedPublisher PD