Measurement of particle motion in optical tweezers embedded in a Sagnac interferometer

We have constructed a counterpropagating optical tweezers setup embedded in a Sagnac interferometer in order to increase the sensitivity of position tracking for particles in the geometrical optics regime. Enhanced position determination using a Sagnac interferometer has previously been described theoretically by Taylor et al. [Journal of Optics 13, 044014 (2011)] for Rayleigh-regime particles trapped in an antinode of a standing wave. We have extended their theory to a case of arbitrarily-sized particles trapped with orthogonally-polarized counterpropagating beams. The working distance of the setup was sufficiently long to optically induce particle oscillations orthogonally to the axis of the tweezers with an auxiliary laser beam. Using these oscillations as a reference, we have experimentally shown that Sagnac-enhanced back focal plane interferometry is capable of providing an improvement of more than 5 times in the signal-to-background ratio, corresponding to a more than 30-fold improvement of the signal-to-noise ratio. The experimental results obtained are consistent with our theoretical predictions. In the experimental setup, we used a method of optical levitator-assisted liquid droplet delivery in air based on commercial inkjet technology, with a novel method to precisely control the size of droplets.Comment: 14 pages, 8 figure

Exploration of a large database of French notarial acts with social network methods

International audienceThis article illustrates how mathematical and statistical tools designed to handle relational data may be useful to help decipher the most important features and defects of a large historical database and to gain knowledge about a corpus made of several thousand documents. Such a relational model is generally enough to address a wide variety of problems, including most databases containing relational tables. In mathematics, it is referred to as a 'network' or a 'graph'. The article's purpose is to emphasize how a relevant relational model of a historical corpus can serve as a theoretical framework which makes available automatic data mining methods designed for graphs. By such methods, for one thing, consistency checking can be performed so as to extract possible transcription errors or interpretation errors during the transcription automatically. Moreover, when the database is so large that a human being is unable to gain much knowledge by even an exhaustive manual exploration, relational data mining can help elucidate the database's main features. First, the macroscopic structure of the relations between entities can be emphasized with the help of network summaries automatically produced by classification methods. A complementary point of view is obtained via local summaries of the relation structure: a set of network-related indicators can be calculated for each entity, singling out, for instance, highly connected entities. Finally, visualisation methods dedicated to graphs can be used to give the user an intuitive understanding of the database. Additional information can be superimposed on such network visualisations, making it possible intuitively to link the relations between entities using attributes that describe each entity. This overall approach is here illustrated with a huge corpus of medieval notarial acts, containing several thousand transactions and involving a comparable number of persons

Re-determination of the Pseudobinary System Li2O-MoO3

The quasi-binary phase diagram lithium oxide - molybdenum(VI) oxide was investigated by differential scanning calorimetry and X-ray diffraction. The four intermediate phases Li4MoO5, Li2MoO4, Li4Mo5O17, and Li2Mo4O13 show incongruent melting. The system has one eutectic point at 50.5 mol% MoO3 and 49.5 mol% LiO0.5 with a eutectic temperature of 524.6 deg C. At this point the melt is in equilibrium with Li2MoO4 and Li4Mo5O17.Comment: excerpt from a published article, with 3 figures and 1 tabl

Multivariate public key cryptography with polynomial composition

This paper presents a new public key cryptography scheme using multivariate polynomials over a finite field. Each multivariate polynomial from the public key is obtained by secretly and repeatedly composing affine transformations with series of quadratic polynomials (in a single variable). The main drawback of this scheme is the length of the public key

La délimitation des territoires paroissiaux dans les pays de moyenne Garonne (Xe-XVe siècles)

Dans l'aire de la confluence Tarn-Aveyron-Garonne, la documentation fait apparaître plusieurs types de paroisses, attachées à différents types d'églises, de l'église annexe au prieuré. Ces différences paraissent plus juridiques ou fiscales que réelles dans le fonctionnement quotidien de la paroisse des paroissiens. Par ailleurs, le processus de territorialisation des paroisses semble tardif et lent à se généraliser. Il s'explique par trois phénomènes qui se mêlent : l'influence de structures issues du passé, la contrainte géographique et les aléas de l'histoire contemporaine du processus de formation.The process of bounding parish territories in Quercy (10th-15th c.). In the confluence area of the Tarn, the Aveyron and the Garonne, documentary evidence shows a wide variety of parishes, attached to different kinds of churches (secondary church, monastic church...). These differences seem to bear more on legal or fiscal status than on the reality of the parish or on parishioners'practice. The process of bounding parish territories was late, and its completion was slow to come about. It was determined by three inter-related factors : the influence of patterns of the past, the topographical constraints, and incidental local circumstances

Miniaturised multi-MEMS sensor development

This paper describes the design, fabrication and initial characterisation of a MEMS-based environmental monitoring system. Intended for use with miniaturised Wireless Sensor Network (WSN) motes, the die measures 3 × 3 mm and incorporates humidity, temperature, corrosion, gas and gas flow velocity sensors on a single substrate. Fabricated using a combination of surface and bulk micromachining technologies, the sensor system is designed to replace discrete components on WSN module boards, thereby minimising space consumption and enabling smaller, cheaper wireless motes. Sensors have been characterised over a wide range of environmental conditions. An analysis of the effects of changes in environmental parameters other than the measurand of interest on the performance of the temperature and humidity sensors has been carried out, and corrections applied where necessary. A variety of corrosion monitors have been demonstrated. A gas flow velocity sensor, based on forced convective heat transfer and which has been thermally isolated from the silicon substrate in order to reduce power consumption and improve sensitivity at low flow-rates, has also been presented. The paper also outlines the design of the next generation sensing platform using the novel 10 mm wireless cube developed at Tyndall

La villa et les autres structures de peuplement dans les pays de moyenne Garonne au VIIe siècle

National audienceThis article aims to study the different forms of settlement in the middle valley of the Garonne from written sources. It has helped to clarify the limits of the villa as their archaeological and historical aspects. The work is also based on a long process of archaeological investigationCet article se propose d'étudier les différentes formes de peuplement dans la moyenne vallée de la Garonne à partir des sources écrites. Il a permis de mieux cerner les contours de la villa tant dans leur aspect archéologique qu'historique. Le travail repose également sur un long travail d'enquête archéologiqu

Development of a microelectromechanical system (MEMS)-based multisensor platform for environmental monitoring

Recent progress in data processing, communications and electronics miniaturization is now enabling the development of low-cost wireless sensor networks (WSN), which consist of spatially distributed autonomous sensor modules that collaborate to monitor real-time environmental conditions unobtrusively and with appropriate levels of spatial and temporal granularity. Recent and future applications of this technology range from preventative maintenance and quality control to environmental modelling and failure analysis. In order to fabricate these low-cost, low-power reliable monitoring platforms, it is necessary to improve the level of sensor integration available today. This paper outlines the microfabrication and characterization results of a multifunctional multisensor unit. An existing fabrication process for Complementary Metal Oxide Semiconductor CMOS-compatible microelectromechanical systems (MEMS) structures has been modified and extended to manufacture temperature, relative humidity, corrosion, gas thermal conductivity, and gas flow velocity sensors on a single silicon substrate. A dedicated signal conditioning circuit layer has been built around this MEMS multisensor die for integration on an existing low-power WSN module. The final unit enables accurate readings and cross-sensitivity compensation thanks to a combination of simultaneous readings from multiple sensors. Real-time communication to the outside world is ensured via radio-frequency protocols, and data collection in a serial memory is also made possible for diagnostics applications