184 research outputs found
Efficient Synthesis of Fluorescent Coumarins and Phosphorous-Containing Coumarin-Type Heterocycles via Palladium Catalyzed Cross-Coupling Reactions
Quantum-chemical calculations on the spectral properties of some aryl substituted 3-
phosphonocoumarins were performed, and the effect of the substituents in the aryl moiety was
evaluated. The structures possessing promising fluorescent properties were successfully synthesized via Suzuki and Sonogashira cross-coupling. The synthetic protocol was also applied for the
phosphorous chemoisomer of 3-phosphonocoumarin, 1,2-benzoxaphosphorin, and their carboxylate
analogues. The optical properties of the arylated and alkynylated products were experimentally
determined. The obtained quantum-chemical and experimental results give the possibility for a
fine tuning of the optical properties of phosphorous-containing coumarin systems by altering the
substituent at its C-6 position
Subsurface carbon: a general feature of noble metals
Carbon moieties on late transition metals are regarded as poisoning agents in heterogeneous catalysis. Recent studies show the promoting catalytic role of subsurface C atoms in Pd surfaces and their existence in Ni and Pt surfaces. Here energetic and kinetic evidence obtained by accurate simulations on surface and nanoparticle models shows that such subsurface C species are a general issue to consider even in coinage noble-metal systems. Subsurface C is the most stable situation in densely packed (111) surfaces of Cu and Ag, with sinking barriers low enough to be overcome at catalytic working temperatures. Low-coordinated sites at nanoparticle edges and corners further stabilize them, even in Au, with negligible subsurface sinking barriers. The malleability of low-coordinated sites is key in the subsurface C accommodation. The incorporation of C species decreases the electron density of the surrounding metal atoms, thus affecting their chemical and catalytic activity
Charting the Atomic C Interaction with Transition Metal Surfaces
Carbon interaction with transition metal (TM) surfaces is a relevant topic in heterogeneous catalysis, either for its poisoning capability, for the recently attributed promoter role when incorporated in the subsurface, or for the formation of early TM carbides, which are increasingly used in catalysis. Herein, we present a high-throughput systematic study, adjoining thermodynamic plus kinetic evidence obtained by extensive density functional calculations on surface models (324 diffusion barriers located on 81 TM surfaces in total), which provides a navigation map of these interactions in a holistic fashion. Correlation between previously proposed electronic descriptors and ad/absorption energies has been tested, with the d-band center being found the most suitable one, although machine learning protocols also underscore the importance of the surface energy and the site coordination number. Descriptors have also been tested for diffusion barriers, with ad/absorption energies and the difference in energy between minima being the most appropriate ones. Furthermore, multivariable, polynomial, and random forest regressions show that both thermodynamic and kinetic data are better described when using a combination of different descriptors. Therefore, looking for a single perfect descriptor may not be the best quest, while combining different ones may be a better path to follow
Nonlinear Parabolic Equations arising in Mathematical Finance
This survey paper is focused on qualitative and numerical analyses of fully
nonlinear partial differential equations of parabolic type arising in financial
mathematics. The main purpose is to review various non-linear extensions of the
classical Black-Scholes theory for pricing financial instruments, as well as
models of stochastic dynamic portfolio optimization leading to the
Hamilton-Jacobi-Bellman (HJB) equation. After suitable transformations, both
problems can be represented by solutions to nonlinear parabolic equations.
Qualitative analysis will be focused on issues concerning the existence and
uniqueness of solutions. In the numerical part we discuss a stable
finite-volume and finite difference schemes for solving fully nonlinear
parabolic equations.Comment: arXiv admin note: substantial text overlap with arXiv:1603.0387
Small Nuclear RNAs Encoded by Herpesvirus saimiri Upregulate the Expression of Genes Linked to T Cell Activation in Virally Transformed T Cells
SummarySeven small nuclear RNAs of the Sm class are encoded by Herpesvirus saimiri (HVS), a γ Herpesvirus that causes aggressive T cell leukemias and lymphomas in New World primates and efficiently transforms T cells in vitro [1–4]. The Herpesvirus saimiri U RNAs (HSURs) are the most abundant viral transcripts in HVS-transformed, latently infected T cells but are not required for viral replication or transformation in vitro [5]. We have compared marmoset T cells transformed with wild-type or a mutant HVS lacking the most highly conserved HSURs, HSURs 1 and 2. Microarray and Northern analyses reveal that HSUR 1 and 2 expression correlates with significant increases in a small number of host mRNAs, including the T cell-receptor β and γ chains, the T cell and natural killer (NK) cell-surface receptors CD52 and DAP10, and intracellular proteins—SKAP55, granulysin, and NKG7—linked to T cell and NK cell activation. Upregulation of three of these transcripts was rescued after transduction of deletion-mutant-HVS-transformed cells with a lentiviral vector carrying HSURs 1 and 2. These changes indicate an unexpected role for the HSURs in regulating a remarkably defined and physiologically relevant set of host targets involved in the activation of virally transformed T cells during latency
Simulation modeling for stratified breast cancer screening : a systematic review of cost and quality of life assumptions
BACKGROUND: The economic evaluation of stratified breast cancer screening gains momentum, but produces also very diverse results. Systematic reviews so far focused on modeling techniques and epidemiologic assumptions. However, cost and utility parameters received only little attention. This systematic review assesses simulation models for stratified breast cancer screening based on their cost and utility parameters in each phase of breast cancer screening and care. METHODS: A literature review was conducted to compare economic evaluations with simulation models of personalized breast cancer screening. Study quality was assessed using reporting guidelines. Cost and utility inputs were extracted, standardized and structured using a care delivery framework. Studies were then clustered according to their study aim and parameters were compared within the clusters. RESULTS: Eighteen studies were identified within three study clusters. Reporting quality was very diverse in all three clusters. Only two studies in cluster 1, four studies in cluster 2 and one study in cluster 3 scored high in the quality appraisal. In addition to the quality appraisal, this review assessed if the simulation models were consistent in integrating all relevant phases of care, if utility parameters were consistent and methodological sound and if cost were compatible and consistent in the actual parameters used for screening, diagnostic work up and treatment. Of 18 studies, only three studies did not show signs of potential bias. CONCLUSION: This systematic review shows that a closer look into the cost and utility parameter can help to identify potential bias. Future simulation models should focus on integrating all relevant phases of care, using methodologically sound utility parameters and avoiding inconsistent cost parameters
Antifascism, the 1956 Revolution and the politics of communist autobiographies in Hungary 1944-2000
This is a postprint of an article whose final and definitive form has been published in Europe-Asia Studies © 2006 University of Glasgow; Europe-Asia Studies is available online at http://www.informaworld.com.Using oral history, this contribution explores the reshaping of individuals' public and private autobiographies in response to different political environments. In particular, it analyses the testimony of those who were communists in Hungary between 1945 and 1956, examining how their experiences of fascism, party membership, the 1956 Revolution and the collapse of communism led them in each case to refashion their life stories. Moreover, it considers how their biographies played varying functions at different points in their lives: to express identification with communism, to articulate resistance and to communicate ambition before 1956; to protect themselves from the state after 1956; and to rehabilitate themselves morally in a society which stigmatised them after 1989.I didn't use this word 'liberation' (felszabadulás), because in 1956 my life really changed. Everybody's lives went through a great change, but mine especially. … I wasn't disgusted with myself that I had called the arrival of the Red Army in 1945 a liberation, but [after 1956] I didn't use it anymore
H\alpha\ spectroscopy and multiwavelength imaging of a solar flare caused by filament eruption
We study a sequence of eruptive events including filament eruption, a GOES
C4.3 flare and a coronal mass ejection. We aim to identify the possible
trigger(s) and precursor(s) of the filament destabilisation; investigate flare
kernel characteristics; flare ribbons/kernels formation and evolution; study
the interrelation of the filament-eruption/flare/coronal-mass-ejection
phenomena as part of the integral active-region magnetic field configuration;
determine H\alpha\ line profile evolution during the eruptive phenomena.
Multi-instrument observations are analysed including H\alpha\ line profiles,
speckle images at H\alpha-0.8 \AA\ and H\alpha+0.8 \AA\ from IBIS at DST/NSO,
EUV images and magnetograms from the SDO, coronagraph images from STEREO and
the X-ray flux observations from FERMI and GOES. We establish that the filament
destabilisation and eruption are the main trigger for the flaring activity. A
surge-like event with a circular ribbon in one of the filament footpoints is
determined as the possible trigger of the filament destabilisation. Plasma
draining in this footpoint is identified as the precursor for the filament
eruption. A magnetic flux emergence prior to the filament destabilisation
followed by a high rate of flux cancelation of 1.34 Mx s
is found during the flare activity. The flare X-ray lightcurves reveal three
phases that are found to be associated with three different ribbons occurring
consecutively. A kernel from each ribbon is selected and analysed. The kernel
lightcurves and H alpha line profiles reveal that the emission increase in the
line centre is stronger than that in the line wings. A delay of around 5-6 mins
is found between the increase in the line centre and the occurrence of red
asymmetry. Only red asymmetry is observed in the ribbons during the impulsive
phases. Blue asymmetry is only associated with the dynamic filament.Comment: Accepted by A&A, 18 pages, 16 figure
Fitting the integrated Spectral Energy Distributions of Galaxies
Fitting the spectral energy distributions (SEDs) of galaxies is an almost
universally used technique that has matured significantly in the last decade.
Model predictions and fitting procedures have improved significantly over this
time, attempting to keep up with the vastly increased volume and quality of
available data. We review here the field of SED fitting, describing the
modelling of ultraviolet to infrared galaxy SEDs, the creation of
multiwavelength data sets, and the methods used to fit model SEDs to observed
galaxy data sets. We touch upon the achievements and challenges in the major
ingredients of SED fitting, with a special emphasis on describing the interplay
between the quality of the available data, the quality of the available models,
and the best fitting technique to use in order to obtain a realistic
measurement as well as realistic uncertainties. We conclude that SED fitting
can be used effectively to derive a range of physical properties of galaxies,
such as redshift, stellar masses, star formation rates, dust masses, and
metallicities, with care taken not to over-interpret the available data. Yet
there still exist many issues such as estimating the age of the oldest stars in
a galaxy, finer details ofdust properties and dust-star geometry, and the
influences of poorly understood, luminous stellar types and phases. The
challenge for the coming years will be to improve both the models and the
observational data sets to resolve these uncertainties. The present review will
be made available on an interactive, moderated web page (sedfitting.org), where
the community can access and change the text. The intention is to expand the
text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics &
Space Scienc
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