Boucher, BK, Rich, AJ, Gobert, D, Gardner, B, Metzner, P, King, C, and Buse, M. The effectiveness of a functional movement assessment and 4-week exercise training program for female high school athletes. J Strength Cond Res 35(1): 102-110, 2021-The extent to which young females participate in school-sponsored athletics has grown significantly over the past 2 decades.
View Article and Find Full Text PDFHow important is the ability to freely control eye movements for reading comprehension? And how does the parser make use of this freedom? We investigated these questions using coregistration of eye movements and event-related brain potentials (ERPs) while participants read either freely or in a computer-controlled word-by-word format (also known as RSVP). Word-by-word presentation and natural reading both elicited qualitatively similar ERP effects in response to syntactic and semantic violations (N400 and P600 effects). Comprehension was better in free reading but only in trials in which the eyes regressed to previous material upon encountering the anomaly.
View Article and Find Full Text PDFRecent research has shown that brain potentials time-locked to fixations in natural reading can be similar to brain potentials recorded during rapid serial visual presentation (RSVP). We attempted two replications of Hagoort, Hald, Bastiaansen, and Petersson [Hagoort, P., Hald, L.
View Article and Find Full Text PDFNucleoside analogs (NAs) are used to treat numerous viral infections and cancer. They compete with endogenous nucleotides (dNTP/NTP) for incorporation into nascent DNA/RNA and inhibit replication by preventing subsequent primer extension. To date, an integrated mathematical model that could allow the analysis of their mechanism of action, of the various resistance mechanisms, and their effect on viral fitness is still lacking.
View Article and Find Full Text PDFProtein-ligand interactions are essential for nearly all biological processes, and yet the biophysical mechanism that enables potential binding partners to associate before specific binding occurs remains poorly understood. Fundamental questions include which factors influence the formation of protein-ligand encounter complexes, and whether designated association pathways exist. To address these questions, we developed a computational approach to systematically analyze the complete ensemble of association pathways.
View Article and Find Full Text PDFPhys Rev E Stat Nonlin Soft Matter Phys
September 2010
In many applications one is interested in finding a simplified model which captures the essential dynamical behavior of a real life process. If the essential dynamics can be assumed to be (approximately) memoryless then a reasonable choice for a model is a Markov model whose parameters are estimated by means of Bayesian inference from an observed time series. We propose an efficient Monte Carlo Markov chain framework to assess the uncertainty of the Markov model and related observables.
View Article and Find Full Text PDFPhys Rev E Stat Nonlin Soft Matter Phys
August 2009
The problem of estimating a Markov transition matrix to statistically describe the dynamics underlying an observed process is frequently found in the physical and economical sciences. However, little attention has been paid to the fact that such an estimation is associated with statistical uncertainty, which depends on the number of observed transitions between metastable states. In turn, this induces uncertainties in any property computed from the transition matrix, such as stationary probabilities, committor probabilities, or eigenvalues.
View Article and Find Full Text PDFAn efficient synthesis of enantiopure 1,3-benzothiazines has been achieved by reaction of cyclic sulfenamides and alkylpropiolate or tosylacetylene catalyzed by cesium fluoride.
View Article and Find Full Text PDFA new methodology, using fluoride ion as a nucleophilic catalyst, was applied for the synthesis of enantiopure 1,4-benzothiazepine from cyclic sulfenamide and electron-deficient acetylene, with high efficiency and atom economy.
View Article and Find Full Text PDFWe report herein an efficient and simple route to synthesize 1-nosyl 3,3-dichloro-beta-lactams using a Staudinger reaction between N-nosyl imines and dichloroketene. The resulting dichloroazetidines were opened to afford highly functionalized building blocks.
View Article and Find Full Text PDFA catalytic diastereoselective sulfonium ylide epoxidation of aldehydes furnished original vinyl epoxides, having an MBH backbone. These highly functionalized building blocks were used for a formal synthesis of the antibiotic conocandin, and opened up a stereodivergent route towards beta-hydroxy-alpha-methylene lactones, core units of naturally occurring compounds. Under acidic conditions, the oxiranes were mainly transformed, with moderate to good yields, into trans beta-hydroxy-alpha-methylene lactones.
View Article and Find Full Text PDFA useful synthesis of rare 1,2-disubstituted ferrocenylalkyl amines with (S(Fc),S) configuration has been achieved in a sequential one-pot methodology from (S)-p-tolylsulfinylferrocene.
View Article and Find Full Text PDFA straightforward and high-yielding access to various [2.2]paracyclophanes possessing a sulfur-based functional group is reported, the key step being a SEAr reaction mediated by a sulfonium salt. The versatility of the methodology was exemplified by an original application in sulfenate salt chemistry, from which a remarkable chirality transfer was observed.
View Article and Find Full Text PDFPhys Rev E Stat Nonlin Soft Matter Phys
December 2007
Markov jump processes can be used to model the effective dynamics of observables in applications ranging from molecular dynamics to finance. In this paper we present a different method which allows the inverse modeling of Markov jump processes based on incomplete observations in time: We consider the case of a given time series of the discretely observed jump process. We show how to compute efficiently the maximum likelihood estimator of its infinitesimal generator and demonstrate in detail that the method allows us to handle observations nonequidistant in time.
View Article and Find Full Text PDFAliphatic thiolates were efficiently converted into the corresponding sulfenates by smooth oxidation with trans-(+/-)-2-tert-butyl-3-phenyloxaziridine at room temperature (five examples). Subsequent electrophilic quench with benzyl bromide led to sulfoxides (S-alkylation) in good to moderate yields. Application of the protocol to an aromatic substrate was also successful.
View Article and Find Full Text PDF[reaction: see text] The in situ preparation of a sulfonium ylide reagent achieved the highly diastereoselective epoxidation of isatins, so that a new and straightforward access to biologically significant spiro-epoxyoxindoles is provided. The first investigations of an asymmetric version are reported with enantiopure sulfides.
View Article and Find Full Text PDF(S)-tert-Butylsulfinylferrocene was submitted to ortho-metalation, and the corresponding lithium derivative was trapped by alkyl or aryl imines bearing various electron-withdrawing groups on the nitrogen atom (Ts, Dpp, Boc). New aminosulfoxides were obtained with complete diastereocontrol when Dpp or Boc groups were used. The absolute configuration (SS,SFc,S) has been determined by single-crystal X-ray analysis and chemical correlation.
View Article and Find Full Text PDFTransition path theory (TPT) has been recently introduced as a theoretical framework to describe the reaction pathways of rare events between long lived states in complex systems. TPT gives detailed statistical information about the reactive trajectories involved in these rare events, which are beyond the realm of transition state theory or transition path sampling. In this paper the TPT approach is outlined, its distinction from other approaches is discussed, and, most importantly, the main insights and objects provided by TPT are illustrated in detail via a series of low dimensional test problems.
View Article and Find Full Text PDFA highly diastereoselective organocatalytic synthesis of unique functionalised vinyl epoxides, displaying a Morita-Baylis-Hillman backbone, has been developed by means of an user friendly sulfonium ylide epoxidation of aldehydes from a readily available alpha-(bromomethyl)acrylamide derivative. The first result in the asymmetric version is discussed.
View Article and Find Full Text PDFEnantiopure aromatic (phenyl, naphthyl) and heteroaromatic (pyridyl, quinolyl, diazinyl) sulfoxides have been synthesized by reaction of (S)-tert-butyl tert-butanethiosulfinate with aryl- or heteroaryllithium derivatives. The ortho-directed metalation of the sulfoxides was performed with lithium bases. Subsequent addition of the lithiated intermediates to N-tosylimines afforded tosylaminoalkyl tert-butylsulfinyl arenes.
View Article and Find Full Text PDF[reaction: see text] A new generation of 2,5-dimethylthiolanes with a locked conformation was developed to promote the asymmetric addition of chiral sulfonium ylides to aldehydes. The novel chiral sulfur derivative 4 succeeded the synthesis of trans-stilbene oxide derivatives with enantiomeric ratios ranging from 95:5 to 98:2. This user-friendly organocatalytic process proved to be efficient with 20-10% of sulfide 4 in 1 or 2 days of reaction.
View Article and Find Full Text PDF[reaction: see text] A general, efficient, and experimentally simple method for the generation of sulfenate salts has been developed using beta-sulfinylesters as substrates. The process is based on a retro-Michael reaction, initiated by deprotonation at low temperature. Upon treatment with alkyl halides, the liberated sulfenates are subsequently converted into sulfoxides in good to excellent yield.
View Article and Find Full Text PDFThe 1,3-asymmetric iodolactonization reaction of enantiopure alpha-sulfurated gamma-unsaturated amides has been investigated. With sulfinyl and sulfonyl groups, a poorly stereoselective reaction was observed, whereas with a sulfanyl moiety, the diastereoselectivity can be high as 96:4. The role of the oxygen atom on the sulfur moiety is discussed.
View Article and Find Full Text PDFAsymmetric allylidenation of aldehydes with sulfur ylides is possible with proper substitution of the initial sulfide, to avoid the [2,3] sigmatropic rearrangement of the unsaturated ylides. One-pot reaction of (2R,5R)-dimethylthiolane with allyl halides, aldehydes, and sodium hydroxide in tert-butyl alcohol affords vinyl oxiranes in good yields. Enantiomeric excesses up to 90% and trans selectivities have been achieved with methallyl-type halides.
View Article and Find Full Text PDFChem Commun (Camb)
November 2001
Enantioenriched selenonium ylides have been generated by addition of benzyl bromide to C2 symmetric (2R,5R)-2,5-dimethylselenolane in the presence of NaOH, and subsequently reacted with a variety of aldehydes to give oxiranes with excellent enantiomeric excesses (a catalytic version has been achieved); also, an aliphatic cyclic hypervalent dibromoselenurane structure has been demonstrated by X-ray analysis.
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