The Detectability Limit of Organic Molecules Within Mars South Polar Laboratory Analogs

A series of laboratory experiments was carried out in order to generate a diagnostic spectrum for Polycyclic Aromatic Hydrocarbons (PAHs) of astrobiological interest in the context of the Martian South Polar Residual Cap (SPRC), to establish PAH spectral features more easily detectable in CO2 ice (mixed with small amounts of H2O ice) than the previously reported absorption feature at 3.29 µm in order to constrain their detectability limit. There is currently no existing literature on PAH detection within SPRC features, making this work novel and impactful given the recent discovery of a possible subglacial lake beneath the Martian South Pole. Although they have been detected in Martian meteorites, PAHs have not been detected yet on Mars, possibly due to the deleterious effects of ultraviolet radiation on the surface of the planet. SPRC features may provide protection to fragile molecules, and this work seeks to provide laboratory data to improve interpretation of orbital remote sensing spectroscopic imaging data. We also ascertain the effect of CO2 ice sublimation on organic spectra, as well as provide PAH reference spectra in mixtures relevant to Mars. A detectability limit of ∼0.04% has been recorded for observing PAHs in CO2 ice using laboratory instrument parameters emulating those of the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), with new spectral slope features revealed between 0.7 and 1.1 µm, and absorption features at 1.14 and, most sensitively, at 1.685 µm. Mars regolith analogue mixed with a concentration of 1.5% PAHs resulted in no discernible organic spectral features. These detectability limits measured in the laboratory are discussed and extrapolated to the effective conditions on the Mars South Polar Cap in terms of dust and water ice abundance and CO2 ice grain size for both the main perennial cap and the H2O ice-dust sublimation lag deposit

VNIR Spectral Change of Hydrated Sulfate Minerals at Different Low Temperatures

Reflectance VNIR laboratory spectra of hydrated sulfates measured at different low temperatures and variable particle sizes as a tool for planetary mineralogy

The prognostic value of multivoxel magnetic resonance spectroscopy determined metabolite levels in white and grey matter brain tissue for adverse outcome in term newborns following perinatal asphyxia

Magnetic resonance spectroscopy can identify brain metabolic changes in perinatal asphyxia by providing ratios of metabolites, such as choline (Cho), creatine (Cr), N-acetyl aspartate (NAA) and lactate (Lact) [Cho/Cr, Lact/NAA, etc.]. The purpose of this study was to quantify the separate white and grey matter metabolites in a slab cranial to the ventricles and relate these to the outcome. A standard 2D-chemical shift imaging protocol was used for measuring a transverse volume of interest located cranial to the ventricles allowing for direct comparison of the metabolites in white and grey matter brain tissue in 24 term asphyxiated newborns aged 3 to 16 days. Cho, NAA and Lact showed significant differences between four subgroups of asphyxiated infants with more and less favourable outcomes. High levels of Cho and Lact in the grey matter differentiated non-survivors from survivors (P = 0.003 and P = 0.017, respectively). In perinatal asphyxia the levels of Cho, NAA and Lact in both white and grey matter brain tissue are affected. The levels of Cho and Lact measured in the grey matter are the most indicative of survival. It is therefore advised to include grey matter brain tissue in the region of interest examined by multivoxel MR spectroscopy. aEuro cent Magnetic resonance spectroscopy can identify brain metabolic changes in perinatal asphyxia. aEuro cent Choline and lactate levels in grey matter seem the best indicators of survival. aEuro cent Both grey and white matter should be examined during spectroscopy for perinatal asphyxia

Advances and new applications using the acousto-optic effect in optical fibers

This work presents a short review of the current research on the acousto-optic mechanism applied to optical fibers. The role of the piezoelectric element and the acousto-optic modulator in the excitation of flexural and longitudinal acoustic modes in the frequency range up to 1.2 MHz is highlighted. A combination of the finite elements and the transfer matrix methods is used to simulate the interaction of the waves with Bragg and long period gratings. Results show a very good agreement with experimental data. Recent applications such as the writing of gratings under the acoustic excitation and a novel viscometer sensor based on the acousto-optic mechanism are discussed

Acromegaly and gigantism in the medical literature. Case descriptions in the era before and the early years after the initial publication of Pierre Marie (1886)

In 1886 Pierre Marie used the term “acromegaly” for the first time and gave a full description of the characteristic clinical picture. However several others had already given clear clinical descriptions before him and sometimes had given the disease other names. After 1886, it gradually became clear that pituitary enlargement (caused by a pituitary adenoma) was the cause and not the consequence of acromegaly, as initially thought. Pituitary adenomas could be found in the great majority of cases. It also became clear that acromegaly and gigantism were the same disease but occurring at different stages of life and not different diseases as initially thought. At the end of the 19th and beginning of the 20th century most information was derived from case descriptions and post-mortem examinations of patients with acromegaly or (famous) patients with gigantism. The stage was set for further research into the pathogenesis, diagnosis and therapy of acromegaly and gigantism

«La relation de limitation et d’exception dans le français d’aujourd’hui : excepté, sauf et hormis comme pivots d’une relation algébrique »

L’analyse des emplois prépositionnels et des emplois conjonctifs d’ “excepté”, de “sauf” et d’ “hormis” permet d’envisager les trois prépositions/conjonctions comme le pivot d’un binôme, comme la plaque tournante d’une structure bipolaire. Placées au milieu du binôme, ces prépositions sont forcées par leur sémantisme originaire dûment métaphorisé de jouer le rôle de marqueurs d’inconséquence systématique entre l’élément se trouvant à leur gauche et celui qui se trouve à leur droite. L’opposition qui surgit entre les deux éléments n’est donc pas une incompatibilité naturelle, intrinsèque, mais extrinsèque, induite. Dans la plupart des cas (emplois limitatifs), cette opposition prend la forme d’un rapport entre une « classe » et le « membre (soustrait) de la classe », ou bien entre un « tout » et une « partie » ; dans d’autres (emplois exceptifs), cette opposition se manifeste au contraire comme une attaque de front portée par un « tout » à un autre « tout ». De plus, l’inconséquence induite mise en place par la préposition/conjonction paraît, en principe, tout à fait insurmontable. Dans l’assertion « les écureuils vivent partout, sauf en Australie » (que l’on peut expliciter par « Les écureuils vivent partout, sauf [qu’ils ne vivent pas] en Australie »), la préposition semble en effet capable d’impliquer le prédicat principal avec signe inverti, et de bâtir sur une telle implication une sorte de sous énoncé qui, à la rigueur, est totalement inconséquent avec celui qui le précède (si « les écureuils ne vivent pas en Australie », le fait qu’ils « vivent partout » est faux). Néanmoins, l’analyse montre qu’alors que certaines de ces oppositions peuvent enfin être dépassées, d’autres ne le peuvent pas. C’est, respectivement, le cas des relations limitatives et des relations exceptives. La relation limitative, impliquant le rapport « tout » - « partie », permet de résoudre le conflit dans les termes d’une somme algébrique entre deux sous énoncés pourvus de différent poids informatif et de signe contraire. Les valeurs numériques des termes de la somme étant déséquilibrées, le résultat est toujours autre que zéro. La relation exceptive, au contraire, qui n’implique pas le rapport « tout » - « partie », n’est pas capable de résoudre le conflit entre deux sous énoncés pourvus du même poids informatif et en même temps de signe contraire : les valeurs numériques des termes de la somme étant symétriques et égales, le résultat sera toujours équivalent à zéro

MAORY: adaptive optics module for the E-ELT

MAORY is one of the four instruments for the E-ELT approved for construction. It is an adaptive optics module offering two compensation modes: multi-conjugate and single-conjugate adaptive optics. The project has recently entered its phase B. A system-level overview of the current status of the project is given in this paper