Ultrafast internal conversion and photochromism in gas-phase salicylideneaniline

Salicylideneaniline (SA) is an archetypal system for excited-state intramolecular proton transfer (ESIPT) in non-planar systems. Multiple channels for relaxation involving both the keto and enol forms have been proposed after excitation to S1 with near-UV light. Here, we present transient absorption measurements of hot gas-phase SA, jet-cooled SA, and SA in Ar clusters using cavity-enhanced transient absorption spectroscopy (CE-TAS). Assignment of the spectra is aided by simulated TAS spectra, computed by applying time-dependent complete active space configuration interaction (TD-CASCI) to structures drawn from nonadiabatic molecular dynamics simulations. We find prompt ESIPT in all conditions followed by the rapid generation of the trans keto metastable photochrome state and fluorescent keto state in parallel. Increasing the internal energy increases the photochrome yield and decreases the fluorescent yield and fluorescent state lifetime observed in TAS. In Ar clusters, internal conversion of SA is severely hindered, but the photochrome yield is unchanged. Taken together, these results are consistent with the photochrome being produced via the vibrationally excited keto population after ESIPT

Ultrafast internal conversion and photochromism in gas-phase salicylideneaniline

Salicylidenaniline (SA) is an archetypal system for excited-state intramolecular proton transfer (ESIPT) in non-planar systems. Multiple channels for relaxation involving both the keto and enol forms have been proposed after excitation to S$_1$ with near-UV light. Here we present transient absorption measurements of hot gas-phase SA, jet-cooled SA, and SA in Ar clusters using cavity-enhanced transient absorption spectroscopy (CE-TAS). Assignment of the spectra is aided by simulated TAS spectra, computed by applying time-dependent complete active space configuration interaction (TD-CASCI) to structures drawn from nonadiabatic molecular dynamics simulations. We find prompt ESIPT in all conditions followed by the rapid parallel generation of the trans-keto metastable photochrome state and fluorescent keto state in parallel. Increasing the internal energy increases the photochrome yield and decreases the fluorescent yield and fluorescent state lifetime observed in TAS. In Ar clusters, internal conversion of SA is severely hindered but the photochrome yield is unchanged. Taken together, these results are consistent with the photochrome being produced via the vibrationally excited keto population after ESIPT

Debate:Challenges in sports cardiology; US versus European approaches

For practitioners working with elite athletes, the field of sports cardiology provides clinical, academic, administrative and fiscal challenges. These challenges are exemplified and reinforced by the lack of consistency and consensus both in the literature and academic presentations. Through thepresentation of a series of clinical questions, this debate attempts to ‘cut to the chase’ on cardiovascular issues relevant to the clinician dealing with elite athletes. In so doing, we hope to crystallize some of the most important elements of the complex cardiological management of elite athletes, in a concise, readable format. Frequently over the last 10 years, many of the controversies in this field have been (rightly or wrongly) presented in aEurope versus USA paradigm. We have chosen to test whether there really are polarised views across the Atlantic, by deliberately pitting specialists from the USA against those from the UK. Professors Levine and Thompson are both internationally recognised sports cardiologists, with immense academic and clinical credibility, and who will represent the ‘US approach’. Professor Whyte and Doctor Wilson are cardiac physiologists with a wealth of experience in the testing, evaluation and screening of elite athletes, and who have equally impressive academic credibility and for the purposes of this debate, they will be representing the ‘European approach’. To initiate this process, each team was required to provide a concise answer (circa 200–300 words) to a series of fiveclinical conundrums. Subsequently, each team had the opportunity to provide a rebuttal to the opposing team’s answers, and the following reflects the consolidation of those answers

Inhibition of Nitric Oxide Inhibition of Nitric Oxide Synthase Does Not Alter Dynamic Cerebral Autoregulation in Humans

The aim of this study was to determine whether inhibition of nitric oxide synthase (NOS) alters dynamic cerebral autoregulation in humans. Beat-to-beat blood pressure (BP) and cerebral blood flow (CBF) velocity (transcranial Doppler) were measured in eight healthy subjects in the supine position and during 60° head-up tilt (HUT). NOS was inhibited by intravenous N G-monomethyl-L-arginine (L-NMMA) infusion. Dynamic cerebral autoregulation was quantified by transfer function analysis of beat-to-beat changes in BP and CBF velocity. Pressor effects of L-NMMA on cerebral hemodynamics were compared with those of phenylephrine infusion. In the supine position, L-NMMA increased mean BP from 83 ± 3 to 94 ± 3 mmHg (P \u3c 0.01). However, CBF velocity remained unchanged. Consequently, cerebrovascular resistance index (CVRI) increased by 15% (P \u3c 0.05). BP and CBF velocity variability and transfer function gain at the low frequencies of 0.07-0.20 Hz did not change with L-NMMA infusion. Similar changes in mean BP, CBF velocity, and CVRI were observed after phenylephrine infusion, suggesting that increase in CVRI after L-NMMA was mediated myogenically by increase in arterial pressure rather than a direct effect of cerebrovascular NOS inhibition. During baseline tilt without L-NMMA, steady-state BP increased and CBF velocity decreased. BP and CBF velocity variability at low frequencies increased in parallel by 277% and 217%, respectively (P \u3c 0.05). However, transfer function gain remained unchanged. During tilt with L-NMMA, changes in steady-state hemodynamics and BP and CBF velocity variability as well as transfer gain and phase were similar to those without L-NMMA. These data suggest that inhibition of tonic production of NO does not appear to alter dynamic cerebral autoregulation in humans

Nitric Oxide Synthase Inhibition Does Not Affect Regulation of Muscle Sympathetic Nerve Activity During Head-Up Tilt

To test the hypothesis that systemic inhibition of nitric oxide (NO) synthase does not alter the regulation of sympathetic outflow during head-up tilt in humans, in eight healthy subjects NO synthase was blocked by intravenous infusion of NG-monomethyl-L-arginine (L-NMMA). Blood pressure, heart rate, cardiac output, total peripheral resistance (TPR), and muscle sympathetic nerve activity (MSNA) were recorded in the supine position and during 60° head-up tilt. In the supine position, infusion of L-NMMA increased blood pressure, via increased TPR, and inhibited MSNA. However, the increase in MSNA evoked by head-up tilt during L-NMMA infusion (change in burst rate: 24 ± 4 bursts/min; change in total activity: 209 ± 36 U/min) was similar to that during head-up tilt without L-NMMA (change in burst rate: 23 ± 4 bursts/min; change in total activity: 251 ± 52 U/min, n = 6, all P \u3e 0.05). Moreover, changes in TPR and heart rate during head-up tilt were virtually identical between the two conditions. These results suggest that systemic inhibition of NO synthase with L-NMMA does not affect the regulation of sympathetic outflow and vascular resistance during head-up tilt in humans

Searching for spiral features in the outer Galactic disk. The field towards WR38 and WR38a

The detailed spiral structure in the outer Galactic disk is still poorly known, and for several Galactic directions we rely on model extrapolations. One of these regions is the fourth Galactic quadrant, in the sector comprised between Vela and Carina (270 <l< 300) where no spiral arms have been detected so far in the optical beyond 270. By means of deep UBVI photometry, we search for spiral features in known low absorption windows.U photometry, although demanding, constitutes a powerful tool to detect and characterize distant aggregates, and allows to derive firmer distance estimates. We studied a direction close to the tangent (l=290) to the Carina arm, in an attempt to detect optical spiral tracers beyond the Carina branch, where radio observations and models predictions indicate the presence of the extension of the Perseus and Norma-Cygnus spiral arms in the fourth quadrant.Along this line of sight, we detect three distinct groups of young stars. Two of them, at 2.5 and 6.0 kpc, belong to the Carina spiral arm (which is crossed twice in this particular direction).The latter is here detected for the first time. The third group, at a distance of 12.7 kpc, is part of the Perseus arm which lies beyond the Carina arm, and constitutes the first optical detection of this arm in the fourth Galactic quadrant. The position of this feature is compatible with HI observations and model predictions. We furthermore present evidence that this extremely distant group, formerly thought to be a star cluster (Shorlin 1), is in fact a diffuse young population. In addition, our data-set does not support the possible presence of the Monoceros Ring toward this direction. This study highlights how multicolor optical studies can be effective to probe the spiral structure in the outer Galactic disk.Comment: 9 pages, 13 eps figure, in press in A&A, abstract rephrased and a few figures degraded in resolution to fit i

Extension of corporate services brands: the effect of perceived similarity extension and perceived quality brand

O principal objetivo deste estudo é avaliar o efeito da qualidade percebida da marca-mãe e da similaridade percebida sobre as avaliações de extensões de marcas corporativas de serviços. Adicionalmente, também se deseja verificar se a elaboração das características da extensão contribuem para a sua avaliação. As hipóteses foram testadas por meio de três experimentos que envolveram no total 1.131 respondentes. No Estudo 1 foram utilizadas marcas fictícias como estímulo e verificou-se que a qualidade da marca-mãe teve efeito mais importante que a similaridade percebida sobre as avaliações de uma extensão de marca de serviços. No Estudo 2, utilizando como estímulos marcas reais, os mesmos resultados do Estudo 1 foram obtidos. No Estudo 3 verificou-se que a elaboração das características da extensão contribuiu positivamente apenas para uma das extensões propostas para a marca-mãe de alta qualidade, mas não teve nenhum efeito para as extensões propostas para a marca-mãe de baixa qualidade. Tomados em conjunto, os resultados sugerem que a qualidade percebida da marca-mãe tem papel fundamental na avaliação de extensões de marcas corporativas de serviços. O estudo contribui ainda com diversas hipóteses para estudos futuros e implicações gerenciais para gerentes de marcas corporativas de serviços.The main objective of this study is to assess the effect of parent brand perceived quality and perceived similarity on the evaluation of corporate service brand extensions. It is also the intention of this study to verify whether providing information cues about the characteristics of the extension contributes to the brand extension evaluation. The hypotheses were tested by means of three experiments involving 1,131 subjects. The results of Study 1, conducted with fictitious brands as stimuli, demonstrated that the perceived quality of the parent brand played a more significant role than perceived similarity on the evaluations of brand extensions. In Study 2, where real brands were used as stimuli, the results were the same as in Study 1. Study 3 found that providing information cues about the characteristics of the extensions had a positive effect for one of the extensions of the high quality parent brand but not for the two proposed extensions of the low quality parent brand. Taken as a whole, the results suggest that the perceived quality of the parent-brand plays a fundamental role in the evaluation of corporate service brand extensions. The study also contributes several hypotheses for future studies and managerial implications for managers of corporate service brands

Second harmonic generation in SiC polytypes

LMTO calculations are presented for the frequency dependent second harmonic generation (SHG) in the polytypes 2H, 4H, 6H, 15R and 3C of SiC. All independent tensor components are calculated. The spectral features and the ratios of the 333 to 311 tensorial components are studied as a function of the degree of hexagonality. The relationship to the linear optical response and the underlying band structure are investigated. SHG is suggested to be a sensitive tool for investigating the near band edge interband excitations.Comment: 12 pages, 10 figure

Can We Calculate Mean Arterial Pressure in Humans?

Mean arterial pressure (MAP) is either measured with an oscillometric cuff and then systolic (SBP) and diastolic (DBP) blood pressures are estimated from an unknown algorithm; or SBP and DBP are measured via auscultation and MAP calculated using measures of systolic pressure (SBP), diastolic pressure (DBP), and a form-factor (FF; equation: [(SBP-DBP)*FF]+DBP). The typical FF used is 0.33 though others (0.4) have been proposed. Recent work indicates that estimation of aortic MAP via a FF leads to inaccurate values and should therefore be interpreted with caution, whether this is the case for local MAP is unknown. While the implications for hypertension (HTN) diagnosis are minimal, the calculation of local MAP is essential to the study of blood pressure regulation and exercise hemodynamics in patient populations (e.g. heart failure). PURPOSE: To compare the calculation of local MAP using catheter waveforms and a FF, against MAP derived from the pressure-time integral (PTI; i.e. average pressure across the cardiac cycle) measured via radial arterial catheterization. METHODS: We analyzed radial arterial catheter waveforms from 39 patients (Age: 71±7 years; BMI: 38.4±6.7; Female: 66%; HTN prevalence: 97%) with heart failure with preserved ejection fraction (HFpEF) at rest and during cycling exercise at 20 Watts. We compared the PTI (from the catheter waveform) with the calculation of MAP from the peak and nadir of the same waveforms (5-beat averages) using the 0.33 and 0.4 FF’s in the FF equation. RESULTS: Compared to the PTI (91±13 mmHg), resting MAP was not significantly different when calculated using the 0.33 FF (91±11 mmHg, P\u3e0.999) but was higher when using the 0.4 FF (96±12 mmHg, PCONCLUSION:While the 0.33 FF provides an accurate assessment of MAP on average during rest and exercise in the radial artery in patients with HFpEF, the limits of agreement are large reflecting a lack of precision in measurement at an individual level. Indirect calculations of MAP via a FF may lead to inaccurate conclusions regarding the mechanisms of blood pressure regulation both at rest and during exercise testing in this population