Judging the Risk of Becoming Infected through Sexual Encounters

The authors examine the manner in which people integrate pieces of information to assess the risk of becoming infected through sexual encounters

Pétrarque et Jean de Salisbury: miroir du prince et conceptions politiques

Dans ses oeuvres latines, Pétrarque met en avant les auteurs classiques et patristiques qu'il cite ou imite. Quant aux écrivains du Moyen Âge qu'il a certainement lus et qui l'ont probablement influencés, il n'en parle presque jamais. C'est le cas en particulier pour le philosophe anglais Jean de Salisbury. Il faut donc examiner de près les textes et faire apparaître des similitudes et des parallèles assez précis pour établir avec certitude l'influence de Jean de Salisbury sur la pensée politique de l'humaniste florentin

Pétrarque, lecteur des Tusculanes

Les Tusculanes exercent à la Renaissance une influence particulière, comparées aux autres œuvres du corpus cicéronien. Ce texte, dans l'interprétation qu'en donnent les humanistes, se révèle au confluent des deux cultures, païenne et chrétienne. La lecture par Pétrarque de ce traité et l'usage qu'il en fait, tant dans sa prose latine que dans les poèmes italiens du Canzoniere, sont à cet égard particulièrement significatifs

A model-based acoustic time-reversal mirror for robust variable focusing

A natural extension of the acoustic time-reversal mirror (TRM) is investigated where predicted receive array signals are backpropagated to an arbitrary virtual source location. First, large time-bandwidth product (TB), broadband signals propagating from a real probe source to the array are processed iteratively by a model-based matched filter (MBMF) receiver in searching for the environmental parameters that best correspond to the measured acoustic-impulse responses. The process ends when most of the time-spread energy across the array is recombined coherently (processing gain). Second, the resulting acoustic-channel model is used to synthesize the transmit signals that will focus their energy at the desired range and depth (the virtual source). The procedure overcomes the noise and reverberation limitations inherent to the TRM operation. The at-sea, focusing performances of a model-based TRM were predicted from related MBMF experiments: range-depth localization of a distant towed source in a duct (west sardinia 89\N90) and bottom geoacoustic characterization in shallow water (yellow shark 94\N95) [Hermand et al., IEEE J. Oceanic Eng. 18, 447–465 (1993); 24, 41–66 (1999)]. Simulation results using yellow shark 94, large TB, broadband vertical array data will be compared with trm 96\N97 experimental results [Hodgkiss et al., J. Acoust. Soc. Am. 105, 1597–1604 (1999)] obtained along the same transect

Pétrarque et Quintilien

Il s'agira d'étudier les rapports de l'humaniste florentin Pétrarque avec Quintilien à partir de la lettre fictive qu'il lui adresse (Fam. XXIV, 7) et du manuscrit de l'Institution oratoire qu'il posséda (Parisinus latinus 7720)

On the usefulness of waterborne measurement of particle velocity in geoacoustic inversion

Recent advances in sensor design have led to the development of receiving systems whose elements are vector sensors, i.e., sensors that simultaneously measure the acoustic pressure and fluid motion due to the propagation of acoustic energy at the sensor location. As such, arrays of vector sensors can provide more information about the sound field than arrays made of traditional hydrophones, and thus are attractive for various applications including the inversion for environmental properties. The fundamental question addressed by this paper is: does the use of acoustic vector data versus pressure-only data improve the results of an inversion scheme based on waterborne observations and matched field processing? To our knowledge no experimental data are available yet to allow a detailed comparison of performance between standard (pressure-only) arrays and vector sensor arrays for environmental inversions. For a preliminary study we will simulate the inversion of vector sensor data in the South Elba environment for which pressure-only inversion results and ground truth data are available following the Yellow Shark'94 and Blue Planet'07 experiments. Broadband signals received on fully-populated and sparse arrays will be considered

« Lege memoriter » : lecture, écriture et mémoire chez Pétrarque

Etude de la notion de memoria chez Pétrarque à partir des Rerum memorandarum libri et de la correspondance. Rôle de la mémoire et du souvenir dans les processus de lecture et d'écriture chez Pétrarque

Characterization of Posidonia Oceanica Seagrass Aerenchyma through Whole Slide Imaging: A Pilot Study

Characterizing the tissue morphology and anatomy of seagrasses is essential to predicting their acoustic behavior. In this pilot study, we use histology techniques and whole slide imaging (WSI) to describe the composition and topology of the aerenchyma of an entire leaf blade in an automatic way combining the advantages of X-ray microtomography and optical microscopy. Paraffin blocks are prepared in such a way that microtome slices contain an arbitrarily large number of cross sections distributed along the full length of a blade. The sample organization in the paraffin block coupled with whole slide image analysis allows high throughput data extraction and an exhaustive characterization along the whole blade length. The core of the work are image processing algorithms that can identify cells and air lacunae (or void) from fiber strand, epidermis, mesophyll and vascular system. A set of specific features is developed to adequately describe the convexity of cells and voids where standard descriptors fail. The features scrutinize the local curvature of the object borders to allow an accurate discrimination between void and cell through machine learning. The algorithm allows to reconstruct the cells and cell membrane features that are relevant to tissue density, compressibility and rigidity. Size distribution of the different cell types and gas spaces, total biomass and total void volume fraction are then extracted from the high resolution slices to provide a complete characterization of the tissue along the leave from its base to the apex

NURC/SACLANTCEN milestone experiments toward solving inverse problems in ocean acoustics

This paper reviews milestone experiments conducted by Saclant Undersea Research Centre to support the development and validation of techniques for obtaining and taking into account environmental information in sonar. The experiments brought together underwater acousticians, geophysicists and oceanographers with the aim to collect comprehensive acoustic and environmental ground-truth data. Environmental-adaptive signal processing was first demonstrated in a deep water area (WESTSARDINIA'89&90). From ducted propagation measurements, a model-based matched filter (MBMF) receiver that fully incorporates the physics of wave propagation determined a source range, depth and Doppler. For environmental inversion the broadband extension of matched-field processing was investigated in a shallow water area south of Elba island (YELLOWSHARK'94&95). Geoacoustic properties of the sea bottom were determined by finding the best fit between predicted and observed sound fields at multiple frequencies using genetic search algorithms. The same inversion results were obtained by MBMF processing of broadband linearly-frequency-modulated signals enabling the use of an array of a few hydrophones instead of a dense and large vertical array. This motivated the development of drifting acoustic buoys which were tested successfully over the southern continental shelf off Marettimo island, Sicily (ENVERSE'97&98). A recent experiment demonstrated an integrated concept of Rapid Environmental Assessment (MREA/BP'07) using sparse arrays of hydrophones and pressure/temperature sensors, hand-deployed from small vessels