Three-body interaction-induced light scattering in krypton gas: A computer simulation of the spectral line shapes

he two-, three- and four-body effective collision induced scattering spectral line shapes are calculated for dense gaseous krypton using the pairwise additivity (PA) approximation and different polarizability models. These spectra and several interaction induced spectra calculated at various densities are compared with the experimental measurements of Barocchi et al. [1988, Europhys. Lett., 5, 607]. The potential effect on the spectrum is found to be weak. The results obtained with the Meinander et al. [1986, J. chem. Phys., 84, 3005] empirical polarizability model and molecular dynamics fit well the experimental two- and three-body spectral shapes. The irreducible contribution to the spectral shape is evaluated using the dipole induced dipole irreducible polarizability [buckingham, A. D., and Hands, I. D., 1991, Chem. Phys. Lett., 185, 544]. This contribution is found to be relatively weak for the anisotropic spectra in the frequency and density range studied, explaining the good agreement between the pairwise approximation calculations and the experimental data. The spectra radiated by the quasi-molecules Kr2, Kr3, and Kr4 (the total spectrum within the PA approximation) are also simulated

Prediction of fluid responsiveness using respiratory variations in left ventricular stroke area by transoesophageal echocardiographic automated border detection in mechanically ventilated patients.

BackgroundLeft ventricular stroke area by transoesophageal echocardiographic automated border detection has been shown to be strongly correlated to left ventricular stroke volume. Respiratory variations in left ventricular stroke volume or its surrogates are good predictors of fluid responsiveness in mechanically ventilated patients. We hypothesised that respiratory variations in left ventricular stroke area (DeltaSA) can predict fluid responsiveness.MethodsEighteen mechanically ventilated patients undergoing coronary artery bypass grafting were studied immediately after induction of anaesthesia. Stroke area was measured on a beat-to-beat basis using transoesophageal echocardiographic automated border detection. Haemodynamic and echocardiographic data were measured at baseline and after volume expansion induced by a passive leg raising manoeuvre. Responders to passive leg raising manoeuvre were defined as patients presenting a more than 15% increase in cardiac output.ResultsCardiac output increased significantly in response to volume expansion induced by passive leg raising (from 2.16 +/- 0.79 litres per minute to 2.78 +/- 1.08 litres per minute; p < 0.01). DeltaSA decreased significantly in response to volume expansion (from 17% +/- 7% to 8% +/- 6%; p < 0.01). DeltaSA was higher in responders than in non-responders (20% +/- 5% versus 10% +/- 5%; p < 0.01). A cutoff DeltaSA value of 16% allowed fluid responsiveness prediction with a sensitivity of 92% and a specificity of 83%. DeltaSA at baseline was related to the percentage increase in cardiac output in response to volume expansion (r = 0.53, p < 0.01).ConclusionDeltaSA by transoesophageal echocardiographic automated border detection is sensitive to changes in preload, can predict fluid responsiveness, and can quantify the effects of volume expansion on cardiac output. It has potential clinical applications

Cutoff effect in molecular dynamics simulations of interaction induced light scattering spectra

International audienceA strong dependence of the interaction induced light scattering integrated intensity with the cutoff radius was previously reported in noble liquids molecular dynamics simulations (A.J.C. Ladd, T.A. Litovitz, J.H.R. Clarke, L.V. Woodcock, J. Chem. Phys. 72 (1980) 1759; and J.H.R. Clarke, L.V. Woodcock, Chem. Phys. Lett. 78 (1981) 121). It was concluded that the uncertainties arising from this effect were much larger than can be tolerated in any evaluation of the light scattering mechanism. No real explanation or solution ever appeared in the literature on this problem. Here we report a very strong dependence of the interaction induced spectra calculated by molecular dynamics simulations on the number of atoms used in a liquid argon simulation. We show that this effect is proportional to the square of the density involved in the simulation-4 and that it obeys to a Rcutoff power law with the cutoff radius Rcutoff. To obtain accurate spectra up to high frequency shifts, large cutoff radii have then to be used corresponding to thousands of atoms in the simulation. The time of the simulation is then prohibited. An explanation for both effects is proposed and two different methods to solve this problem are tested. @ 1997 Elsevier Science B.V

Ageing effects in supercooled silica: a molecular dynamics investigation

he two-, three- and four-body effective collision induced scattering spectral line shapes are calculated for dense gaseous krypton using the pairwise additivity (PA) approximation and different polarizability models. These spectra and several interaction induced spectra calculated at various densities are compared with the experimental measurements of Barocchi et al. [1988, Europhys. Lett., 5, 607]. The potential effect on the spectrum is found to be weak. The results obtained with the Meinander et al. [1986, J. chem. Phys., 84, 3005] empirical polarizability model and molecular dynamics fit well the experimental two- and three-body spectral shapes. The irreducible contribution to the spectral shape is evaluated using the dipole induced dipole irreducible polarizability [buckingham, A. D., and Hands, I. D., 1991, Chem. Phys. Lett., 185, 544]. This contribution is found to be relatively weak for the anisotropic spectra in the frequency and density range studied, explaining the good agreement between the pairwise approximation calculations and the experimental data. The spectra radiated by the quasi-molecules Kr2, Kr3, and Kr4 (the total spectrum within the PA approximation) are also simulated

An experimental and numerical study of high-frequency Raman scattering in argon gas

International audienc

Postural change in volunteers: sympathetic tone determines microvascular response to cardiac preload and output increases

Purpose: Microvascular perfusion may be a non-invasive indicator of fluid responsiveness. We aimed to investigate which of the microvascular perfusion parameters truly reflects fluid responsiveness independent of sympathetic reflexes. Methods: Fifteen healthy volunteers underwent a postural change from head up tilt (HUT) to the supine position, diminishing sympathetic tone, followed by a 30° passive leg raising (PLR) with unaltered tone. Prior to and after the postural changes, stroke volume (SV) and cardiac output (CO) were measured, as well as sublingual microcirculatory perfusion (sidestream dark field imaging), skin perfusion, and oxygenation (laser Doppler flowmetry and reflectance spectroscopy). Results: In responders (subjects with >10 % increase in CO), the HUT to supine change increased CO, SV, and pulse pressure, while heart rate, systemic vascular resistance, and mean arterial pressure decreased. Additionally, microvascular flow index, laser Doppler flow, and microvascular hemoglobin oxygen saturation and concentration also increased. Conclusion: When preload and forward flow increase in association with a decrease in sympathetic activity, microvascular blood flow increases in the skin and in the sublingual area. When preload and forward flow increase with little to no change in sympathetic activity, only sublingual functional capillary density increases. Therefore, our results indicate that sublingual functional capillary density is the best pa

Narrative lives: literary self-making in Quebec’s francophone Jewish migrant literature

NARRATIVE LIVES: LITERARY SELF-MAKING IN QUEBEC’S FRANCOPHONE JEWISH MIGRANT LITERATURE To this day, the number of Jewish migrant authors of French-language literature has remained relatively small compared to the large number of authors considered as part of Quebec’s écritures migrantes. Monique Bosco, Naïm Kattan, Pierre Lasry, Victor Teboul, Régine Robin, and Marc-Alain Wolf, are just some, amongst a host of other migrant authors of Jewish origin. Migrant characters who have started a new life in Montreal are often the protagonists of these authors’ novels in which a similarity to the author’s biographies cannot be overlooked. The new lives that the migrant characters lead are more often than not marked and sometimes even haunted by their past. By remembering what happened to them and by telling the story of their life, the narrators/protagonists try to reconstruct a coherent self-identity. Therefore, the article will focus on the particular memories emerging in the process of self-making and will examine the narrative strategies used to highlight the memory process. In a final step, the article will ask to what end the authors may have set their narratives in-between the fictional and the factual genre and what this means for the reception process. ŻYCIE W OPOWIEŚCI. STAWANIE SIĘ SOBĄ POPRZEZ LITERATURĘ WE FRANKOFOŃSKIEJ TWÓRCZOŚCI ŻYDOWSKICH MIGRANTÓW W QUEBECU Liczba pisarzy francuskojęzycznych żydowskiego pochodzenia pozostaje stosunkowo niewielka w zestawieniu z olbrzymim gronem innych autorów migracyjnych w Quebecu. Do autorów pochodzenia żydowskiego należą między innymi Monique Bosco, Naïm Kattan, Pierre Lasry, Victor Teboul, Régine Robin i Marc-Alain Wolf. Bohaterami ich powieści, często auto­biograficznych, są imigranci, którzy rozpoczynają wszystko od nowa po osiedleniu się w Montrealu. Jednak to ich nowe życie bywa naznaczone, a nawet nawiedzane przez przeszłość. Wspominając wcześniejsze życie i opowiadając o nim, bohaterowie i narratorzy próbują zrekonstruować swoją spójną tożsamość. Celem niniejszego artykułu jest analiza roli, jaką w procesie stawania się sobą pełnią wspomnienia, oraz strategii narracyjnych, służących wyrażaniu pracy pamięci. Artykuł stawia również pytanie o funkcję usytuowania badanych utworów na granicy fikcji i autobiografii oraz wpływ takiego usytuowania na proces odbioru.SŁOWA KLUCZOWE: frankofońska literatura kanadyjska; literatura kanadyjsko-żydowska; literatura migrantów; autobiografia; tożsamość; pamięć; Monique Bosco; Naïm Kattan; Pierre Lasry; Victor Teboul; Régine Robin; Marc-Alain Wolf.NARRATIVE LIVES: LITERARY SELF-MAKING IN QUEBEC’S FRANCOPHONE JEWISH MIGRANT LITERATURE To this day, the number of Jewish migrant authors of French-language literature has remained relatively small compared to the large number of authors considered as part of Quebec’s écritures migrantes. Monique Bosco, Naïm Kattan, Pierre Lasry, Victor Teboul, Régine Robin, and Marc-Alain Wolf, are just some, amongst a host of other migrant authors of Jewish origin. Migrant characters who have started a new life in Montreal are often the protagonists of these authors’ novels in which a similarity to the author’s biographies cannot be overlooked. The new lives that the migrant characters lead are more often than not marked and sometimes even haunted by their past. By remembering what happened to them and by telling the story of their life, the narrators/protagonists try to reconstruct a coherent self-identity. Therefore, the article will focus on the particular memories emerging in the process of self-making and will examine the narrative strategies used to highlight the memory process. In a final step, the article will ask to what end the authors may have set their narratives in-between the fictional and the factual genre and what this means for the reception process. ŻYCIE W OPOWIEŚCI. STAWANIE SIĘ SOBĄ POPRZEZ LITERATURĘ WE FRANKOFOŃSKIEJ TWÓRCZOŚCI ŻYDOWSKICH MIGRANTÓW W QUEBECU Liczba pisarzy francuskojęzycznych żydowskiego pochodzenia pozostaje stosunkowo niewielka w zestawieniu z olbrzymim gronem innych autorów migracyjnych w Quebecu. Do autorów pochodzenia żydowskiego należą między innymi Monique Bosco, Naïm Kattan, Pierre Lasry, Victor Teboul, Régine Robin i Marc-Alain Wolf. Bohaterami ich powieści, często auto­biograficznych, są imigranci, którzy rozpoczynają wszystko od nowa po osiedleniu się w Montrealu. Jednak to ich nowe życie bywa naznaczone, a nawet nawiedzane przez przeszłość. Wspominając wcześniejsze życie i opowiadając o nim, bohaterowie i narratorzy próbują zrekonstruować swoją spójną tożsamość. Celem niniejszego artykułu jest analiza roli, jaką w procesie stawania się sobą pełnią wspomnienia, oraz strategii narracyjnych, służących wyrażaniu pracy pamięci. Artykuł stawia również pytanie o funkcję usytuowania badanych utworów na granicy fikcji i autobiografii oraz wpływ takiego usytuowania na proces odbioru.SŁOWA KLUCZOWE: frankofońska literatura kanadyjska; literatura kanadyjsko-żydowska; literatura migrantów; autobiografia; tożsamość; pamięć; Monique Bosco; Naïm Kattan; Pierre Lasry; Victor Teboul; Régine Robin; Marc-Alain Wolf

Noninterventional statistical comparison of BTS and CHEST guidelines for size and severity in primary pneumothorax.

Hilar rather than apical interpleural distance more accurately predicts need for intercostal chest drain insertion http://ow.ly/JvKFYThe study was funded by the East Anglian Thoracic Society. M.Z. Nikolić is a Wellcome Trust PhD Programme for Clinicians Fellow at the University of Cambridge. S.J. Marciniak is a Medical Research Council Senior Clinical Fellow. J. Wason is funded by the Cambridge Biomedical Research Centre. Funding information for this article has been deposited with FundRef.This is the final version of the article. It first appeared from the European Respiratory Society via http://dx.doi.org/10.1183/09031936.0011861

Development of a contra-rotating tidal current turbine and analysis of performance

A contra-rotating marine current turbine has a number of attractive features: nearzero reactive torque on the support structure, near-zero swirl in the wake, and high relative inter-rotor rotational speeds. Modified blade element modelling theory has been used to design and predict the characteristics of such a turbine, and a model turbine and test rig have been constructed. Tests in a towing tank demonstrated the feasibility of the concept. Power coefficients were high for such a small model and in excellent agreement with predictions, confirming the accuracy of the computational modelling procedures. Highfrequency blade loading data were obtained in the course of the experiments. These show the anticipated dynamic components for a contra-rotating machine. Flow visualization of the wake verified the lack of swirl behind the turbine. A larger machine is presently under construction for sea trials