Estimation of the basic reproduction number of measles during an outbreak in a partially vaccinated population

From March to July 1996 a measles outbreak occurred in northern Luxembourg with 110 reported cases centered around two primary schools (85 cases) and the surrounding community (25 cases). Eighty four suspected cases were confirmed serologically. Vaccine coverage was estimated from questionnaire-based surveys at the two primary schools to be 70 and 76%, respectively. Vaccine efficacy during the outbreak was estimated to be 94.6% [95% confidence interval (CI) 90·4–97·0]. Using the information from the school surveys, we obtained estimates of the basic reproduction number of measles of 7·7 (95% CI 4·4–11·0) and 6·2 (95% CI 3·5–8·9), respectively. Assuming a 95% vaccine efficacy, these estimates correspond to minimal vaccine coverages of 91·6% (95% CI 81·4–95·7) and 88·3% (95% CI 75·5–93·4) which would have been necessary to minimize the chances of a major outbreak occurring. We can confirm that major outbreaks in similar school settings can only be prevented if vaccination coverage exceeds 90%

Modeling of a new SMA micro-actuator for active endoscopy applications.

International audienceShape memory alloys (SMA) are good candidates to actuate endoscope heads but the cooling problem must be solved particularly in confined situations. For these reasons, a new SMA micro-actuator specially designed for active endoscopy applications has been developed in our laboratory. This work is a new step in the approach of using integrated thermoelectric cooling with SMA actuators. In fact, the Peltier effect is very attractive in such a case because this reversible phenomenon reduces the overheating of the external environment and provides forced cooling that decreases the response time. In this paper the actuator design and its working principle are presented. A fine modeling of the coupled mechanical and thermal behaviors gives a better understanding of the physical phenomenon involved in the actuator. Finally an experimental prototype has been developed and tested in order to verify the model predictions

Perturbative analysis of generalized Einstein's theories

The hypothesis that the energy-momentum tensor of ordinary matter is not conserved separately, leads to a non-adiabatic expansion and, in many cases, to an Universe older than usual. This may provide a solution for the entropy and age problems of the Standard Cosmological Model. We consider two different theories of this type, and we perform a perturbative analysis, leading to analytical expressions for the evolution of gravitational waves, rotational modes and density perturbations. One of these theories exhibits satisfactory properties at this level, while the other one should be discarded.Comment: 14 pages, Latex fil

Review of Clinical Trials Using Neural Stem Cells

The use of stem cells in clinical trials started several years ago for regenerativebased therapies or for the treatment of tumours. After brain injuries or neurodegenerative diseases, neural stem cells represent a promising strategy to repair the affected tissue and to replace degenerative cells. Neural stem cells can migrate and differentiate into neurons, astrocytes and oligodendrocytes, and thus could serve as promising therapeutic solutions. However, these cells can represent a potential source of cancer stem cells in tumour brain where they are responsible of recurrence, invasiveness and resistance to current treatments. Thus, few clinical trials involving endogenous, genetically modifiedor derived-neural stem cells have been conducted in the world to treat brain disorders. According to the website www.clinicaltrials.gov only 37 clinical trials involving neural stem cells are listed. Most of them use derived-neural stem cells to treat brain disorders (neurodegenerative diseases, injuries or tumours). For the future, a better approach would be to target directly endogenous stem cells.

Spá:A Web-Based Viewer for Text Mining in Evidence Based Medicine

Summarizing the evidence about medical interventions is an immense undertaking, in part because unstructured Portable Document Format (PDF) documents remain the main vehicle for disseminating sci- entific findings. Clinicians and researchers must therefore manually ex- tract and synthesise information from these PDFs. We introduce Spá,12 a web-based viewer that enables automated annotation and summari- sation of PDFs via machine learning. To illustrate its functionality, we use Spá to semi-automate the assessment of bias in clinical trials. Spá has a modular architecture, therefore the tool may be widely useful in other domains with a PDF-based literature, including law, physics, and biology

Experimental Measurement of Human Oocyte Mechanical Properties on a Micro and Nanoforce Sensing Platform Based on Magnetic Springs.

International audienceThis article presents a new micro and nanoforce sensor used to perform a mechanical characterisation of human oocytes. This device is based on the use of low-sti_ness magnetic springs. The oocytes to be characterised are placed on a force-sensitive platform. A manipulator equipped with a standard micropipette is used to mechanically compress the oocyte. Some complete \force-compression length" curves associated with mechanical load-unload cycles are given. These curves show the linear, the non-linear and also the plastic mechanical behaviour of the oocytes. These characterisations must be considered as a preliminary result which illustrates that the mechanical variability and the mechanical evolution of human oocytes during their maturation process can be observed with a force sensor based on magnetic springs

Magnetic shape memory alloy and actuator design.

International audienceIn the field of micromechatronics, microrobotics and specially microfactories, active materials are used in most cases. They permit high resolution and distributed actuation. In this area, Magnetic Shape Memory Alloys (MSMA) are possible candidates. If a lot of studies deal with MSMA, only few applications use them until now. MSMA are attractive active materials because they have large strain (about 10%) as the classical shape memory alloys (SMA), but can provide a 100 times shorter time response. The main disadvantages of MSMA based actuators are the brittleness of the single-crystal material, the difficulty to apply the strong magnetic field required to obtain sufficient strain and the nonlinear behaviour. We propose in this paper a novel MSMA based actuator changing the disadvantage of the hysteretic behaviour into an advantage. This device is a push-pull actuator: two pieces of MSMA material act in an opposite way. The magnetic fields are created by coils and concentrated by ferromagnetic circuits. In order to move the central part of the actuator, a current pulse in the first coil is generated. The hysteretic behaviour of the material permits to keep a stable position when no current is applied. A current pulse in the second coil permits to displace the central part in the opposite direction. The stable position depends on the magnitude and the time duration of the current pulses and an infinity of stable positions can be reached. The use of current pulses permits also a reduction of the coil heating (Joule effect losses) and a reduction of the magnetic circuit size. The performances and characteristics of MSMA are between these of classical SMA and these of piezo-electric materials. A thermo-magneto-mechanical model of our actuator is currently in development in order to design an efficient control law welladapted to the specific MSMA properties

A necklace of Wulff shapes

In a probabilistic model of a film over a disordered substrate, Monte-Carlo simulations show that the film hangs from peaks of the substrate. The film profile is well approximated by a necklace of Wulff shapes. Such a necklace can be obtained as the infimum of a collection of Wulff shapes resting on the substrate. When the random substrate is given by iid heights with exponential distribution, we prove estimates on the probability density of the resulting peaks, at small density

Giant slip lengths of a simple fluid at vibrating solid interfaces

It has been shown recently [PRL 102, 254503 (2009)] that in the plane-plane configuration a mechanical resonator vibrating close to a rigid wall in a simple fluid can be overdamped to a frozen regime. Here, by solving analytically the Navier Stokes equations with partial slip boundary conditions at the solid fluid interface, we develop a theoretical approach justifying and extending these earlier findings. We show in particular that in the perfect slip regime the above mentioned results are, in the plane-plane configuration, very general and robust with respect to lever geometry considerations. We compare the results with those obtained previously for the sphere moving perpendicularly and close to a plane in a simple fluid and discuss in more details the differences concerning the dependence of the friction forces with the gap distance separating the moving object (i.e., plane or sphere) from the fixed plane. Finally, we show that the submicron fluidic effect reported in the reference above, and discussed further in the present work, can have dramatic implications in the design of nano-electromechanical systems (NEMS).Comment: submitted to PRE (see also PRL 102, 254503 (2009)