30,087 research outputs found
Benchmarking the Molecular Mechanics−Valence Bond Method: Photophysics of Styrene and Indene
No full textWe have recently studied the excited states of the simplest aryl olefin styrene (Bearpark, M. J.; Olivucci, M.; Wilsey, S.; Bernardi, F.; Robb, M. A. J. Am. Chem: Sec. 1995, 117, 6944-6953) at the CASSCF/4-31G level of theory. Full geometry optimization was shown to be essential in characterizing decay funnels for internal conversion (activated) and intersystem crossing (activationless) processes in this molecule. Here, we demonstrate that the CASSCF potential energy surfaces for styrene excited states can be simulated to an acceptable level of accuracy using a hybrid molecular mechanics-valence bond method (MMVB), which is many orders of magnitude less expensive computationally than CASSCF. The nonradiative deactivation of styrene and indene from Si is compared. Because ethylene torsions are restricted, the mechanism proposed for styrene S-1 decay (involving S-1/T-2, T-2/T-1, and T-1/S-0 surface crossings) is much less likely to occur in indene. The existence of both S-2/S-1 and S-1/S-0 conical intersections is consistent with the lack of fluorescence observed after exciting indene to S-2 in the gas phase and suggests that rearrangement reactions may be due to vibrationally excited S-0*
Letter from Carl Hayden to Henry F. Ashurst
No full textLetter describing three enclosures, a letter from F. M. Gold, Carl T. Hayden's reply to Gold's letter, and a copy of a bill introduced by Cameron
Letter from A. F. Potter to Carl Hayden
No full textLetter from A. F. Potter to Carl T. Hayden describing John H. Page's request to build a railway for the Canyon Copper Company as "impractical"
FIGURE 9 in Geographic variation and phylogenetic relationships of Myiopagis olallai (Aves: Passeriformes; Tyrannidae), with the description of two new taxa from the Northern Andes
No full textFIGURE 9. Spread left wing from the holotype of Myiopagis olallai coopmansi (ICN 38437).Published as part of Cuervo, Andrés M., Stiles, F. Gary, Lentino, Miguel, Brumfield, Robb T. & Derryberry, Elizabeth P., 2014, Geographic variation and phylogenetic relationships of Myiopagis olallai (Aves: Passeriformes; Tyrannidae), with the description of two new taxa from the Northern Andes, pp. 1-24 in Zootaxa 3873 (1) on page 14, DOI: 10.11646/zootaxa.3873.1.1, http://zenodo.org/record/28723
Product Distributions from Molecular Mechanics−Valence Bond Dynamics: Modeling Photochemical [4 + 4] Cycloadditions
No full textThe purpose of this paper is to study the model [4 + 4] photocycloaddition of butadiene + butadiene by using direct dynamics calculations-with no geometric constraints-to describe motion along excited-state reaction paths and subsequent decay to the ground state. We use the molecular mechanics-valence bond (MMVB) potential, which is calibrated against previous CASSCF calculations for this system (Bearpark, M. J.; Deumal, M.; Robb, M. A.; Vreven, T.; Yamamoto, N.; Olivucci, M.; Bernardi, F. J. Am. Chem. Sec. 1997, 119, 709-718). Our dynamics calculations show that efficient nonradiative decay of butadiene + butadiene in the presence of two different S-1/S-0 conical intersections can account for the formation of many products. The major product predicted by MMVB is consistent with the limited experimental data available
DNA fusion gene vaccination mobilizes effective anti-leukemic cytotoxic T lymphocytes from a tolerized repertoire
No full textThe majority of known human tumor-associated antigens derive from non-mutated self proteins. T cell tolerance, essential to prevent autoimmunity, must therefore be cautiously circumvented to generate cytotoxic T cell responses against these targets. Our strategy uses DNA fusion vaccines to activate high levels of peptide-specific CTL. Key foreign sequences from tetanus toxin activate tolerance-breaking CD4+ T cell help. Candidate MHC class Ibinding tumor peptide sequences are fused to the C terminus for optimal processing and presentation. To model performance against a leukemia-associated antigen in a tolerized setting, we constructed a fusion vaccine encoding an immunodominant CTL epitopederived from Friend murine leukemia virus gag protein (FMuLVgag) and vaccinated tolerant FMuLVgag-transgenic (gag-Tg) mice. Vaccination with the construct induced epitopespecificIFN-c-producing CD8+ T cells in normal and gag-Tg mice. The frequency and avidity of activated cells were reduced in gag-Tg mice, and no autoimmune injury resulted. However, these CD8+ T cells did exhibit gag-specific cytotoxicity in vitro and in vivo. Also, epitope-specific CTL killed FBL-3 leukemia cells expressing endogenous FMuLVgag antigen and protected against leukemia challenge in vivo. These results demonstrate a simple strategy to engage anti-microbial T cell help to activate epitope-specific polyclonal CD8+ T cell responses from a residual tolerized repertoire
Elaboration on Kwapien's theorem: Representing bounded mean zero functions f as coboundary f = g ◦ T − g
No full textIn [8] Kwapien proved that every mean zero function f ∈ L∞[0, 1] we can write as f = g ◦ T − g for some g ∈ L∞[0, 1] and some measure preserving transformation T of [0, 1]. However, as was discovered in [4] there is a gap in the proof for the case that f is not continuous. The aim of this bachelor thesis is filling in that gap in the proof. We first extend Kwapien’s proof for continuous functions to certain other measure spaces. Thereafter, we use the method of proof suggested by Kwapien, to proof the theorem for mean zero function f ∈ L∞[0, 1] for which λ(f−1({x})) = 0 for all x ∈ R. Using this result we then proof that every mean zero function f ∈ L∞[0, 1] can be written as a sum f =(g1 ◦ T1 − g1) + (g2 ◦ T2 − g2) where g1, g2 ∈ L∞[0, 1] and where T1, T2 are measure preserving transformations of [0, 1]. We finish this thesis with an application of Kwapien’s theorem in the study to singular traces Applied Mathematic
f(G,T) and its Cosmological Implications
No full textA coupled formulation of the Gauss-Bonnet invariant term G and the
energy momentum trace T term provide a modified f(G,T) gravity,
has been analyzed in this study. The functional form for the
f(G,T) gravity has been taken as f(G,T)=αT+ βGThe presentation of the authors' names and (or) special characters in the title of the pdf file of the accepted manuscript may differ slightly from what is displayed on the item page. The information in the pdf file of the accepted manuscript reflects the original submission by the author
Bianchi type-I universe in f(R, T) modified gravity with quark matter and Λ
No full text32nd International Physics Congress of Turkish-Physical-Society (TPS) -- SEP 06-09, 2016 -- Bodrum, TURKEYIn this study, we investigate homogeneous and anisotropic Bianchi type I universe in the presence of quark matter source in f (R, T) gravity (Harko et al. in Phys. Rev. D 84:024020, 2011) with cosmological constant A (where R is the Ricci scalar and T is the trace of the energy momentum tensor). For this aim we have used the anisotropy feature of Bianchi type I universe and equation of states (EoS) of quark matter. We explore the exact solution f(R, T)=R + 2f(T) model for Bianchi type I universe model. When t -> infinity, we get very small cosmological constant value, this result agrees with recent observations.Turkish Phys So
Socioeconomic Influence on the Health of Older People: Estimates Based on Two Longitudinal Surveys
No full textThere is a strong positive relationship between socioeconomic status (SES) and health, but identifying the direction of causation is difficult. This study exploits the longitudinal nature of two Canadian surveys, the Survey of Labour and Income Dynamics and the National Population Health Survey, to study the link from SES to health. For people aged 50 and older who are initially in good health we examine whether changes in health status over the next two to four years are related to prior SES, as represented by income and education. Although the two surveys were designed for quite different purposes the evidence they yield with respect to the probability of remaining in good health is strikingly similar. Both suggest that SES does play a role, that the differences across SES groups are quantitatively significant, that the differences increase with age, and that they are much same for men and women.health; socioeconomic status; SLID; NPHS
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