Multidisciplinary Control of a Sparse Interferometric Array Satellite Testbed

The MIT Adaptive Reconnaissance Golay-3 Optical Satellite (ARGOS) is a wide-angle Fizeau interferometer spacecraft testbed. Designing a space-based interferometer, which requires such high tolerances on pointing and alignment for its apertures, presents unique multidisciplinary challenges in the areas of structural dynamics, controls and multi-aperture phasing active optics. In meeting these challenges, emphasis is placed on modularity in spacecraft subsystems and optics as a means of allowing expandability and upgradeability. For the interferometer to function properly, unique methods of coherent wave front sensing are developed and used for error detection in control of the Fast Steering Mirrors (FSMs). The space environment is simulated by floating ARGOS on a frictionless air-bearing that allows it to track fast moving satellites such as the International Space Station (ISS), planets or point stars. A System Identification is performed on ARGOS to determine its dynamic properties and to design optimal controllers for the Attitude Control System (ACS). ACS sensors include an electronic compass with a 2-axis tip-tilt sensor, a viewfinder camera with centroiding algorithm, and a 3-axis rate gyroscope. Nonlinear, quaternion-based control is employed using reaction wheels as the spacecraft's actuators

Discovery of the peculiar supernova 1998bw in the error box of GRB980425

The discovery of X-ray, optical and radio afterglows of gamma-ray bursts (GRBs) and the measurements of the distances to some of them have established that these events come from Gpc distances and are the most powerful photon emitters known in the Universe, with peak luminosities up to 10^52 erg/s. We here report the discovery of an optical transient, in the BeppoSAX Wide Field Camera error box of GRB980425, which occurred within about a day of the gamma-ray burst. Its optical light curve, spectrum and location in a spiral arm of the galaxy ESO 184-G82, at a redshift z = 0.0085, show that the transient is a very luminous type Ic supernova, SN1998bw. The peculiar nature of SN1998bw is emphasized by its extraordinary radio properties which require that the radio emitter expand at relativistical speed. Since SN1998bw is very different from all previously observed afterglows of GRBs, our discovery raises the possibility that very different mechanisms may give rise to GRBs, which differ little in their gamma-ray properties.Comment: Under press embargo at Nature (submitted June 10, 1998

The effects of neuromuscular electrical stimulation for dysphagia in opercular syndrome: a case study

A 76-year-old man with opercular syndrome characterized by complete bilateral loss of voluntary control of facial, lingual, pharyngeal and masticatory muscles is presented with focus on the severe dysphagia. Three years earlier the patient had experienced two strokes resulting in opercular syndrome with severe dysphagia. Despite initial logopedic dysphagia treatment, swallowing did not improve. A new treatment for dysphagia, consisting of neuromuscular electrical stimulation was applied on the patient. He returned to oral feeding. Clinical and treatment observations are reported

Height and timing of growth spurt during puberty in young people living with vertically acquired HIV in Europe and Thailand.

OBJECTIVE: The aim of this study was to describe growth during puberty in young people with vertically acquired HIV. DESIGN: Pooled data from 12 paediatric HIV cohorts in Europe and Thailand. METHODS: One thousand and ninety-four children initiating a nonnucleoside reverse transcriptase inhibitor or boosted protease inhibitor based regimen aged 1-10 years were included. Super Imposition by Translation And Rotation (SITAR) models described growth from age 8 years using three parameters (average height, timing and shape of the growth spurt), dependent on age and height-for-age z-score (HAZ) (WHO references) at antiretroviral therapy (ART) initiation. Multivariate regression explored characteristics associated with these three parameters. RESULTS: At ART initiation, median age and HAZ was 6.4 [interquartile range (IQR): 2.8, 9.0] years and -1.2 (IQR: -2.3 to -0.2), respectively. Median follow-up was 9.1 (IQR: 6.9, 11.4) years. In girls, older age and lower HAZ at ART initiation were independently associated with a growth spurt which occurred 0.41 (95% confidence interval 0.20-0.62) years later in children starting ART age 6 to 10 years compared with 1 to 2 years and 1.50 (1.21-1.78) years later in those starting with HAZ less than -3 compared with HAZ at least -1. Later growth spurts in girls resulted in continued height growth into later adolescence. In boys starting ART with HAZ less than -1, growth spurts were later in children starting ART in the oldest age group, but for HAZ at least -1, there was no association with age. Girls and boys who initiated ART with HAZ at least -1 maintained a similar height to the WHO reference mean. CONCLUSION: Stunting at ART initiation was associated with later growth spurts in girls. Children with HAZ at least -1 at ART initiation grew in height at the level expected in HIV negative children of a comparable age

Insufficient antiretroviral therapy in pregnancy: missed opportunities for prevention of mother-to-child transmission of HIV in Europe

Background: Although mother-to-child transmission (MTCT) rates are at an all-time low in Western Europe, potentially preventable transmissions continue to occur. Duration of antenatal combination antiretroviral therapy (ART) is strongly associated with MTCT risk.Methods: Data on pregnant HIV-infected women enrolled in the Western and Central European sites of the European Collaborative Study between January 2000 and July 2009 were analysed. The proportion of women receiving no antenatal ART or 1-13 days of treatment was investigated, and associated factors explored using logistic regression models.Results: Of 2,148 women, 142 (7%) received no antenatal ART, decreasing from 8% in 2000-2003 to 5% in 2004-2009 (chi(2)=8.73; P= 14 days antenatal ART and 7.4% (10/136) among those with insufficient ART.Conclusions: Over the last 10 years, around one in 11 women in this study received insufficient antenatal ART, accounting for 40% of MTCTs. One-half of these women were diagnosed before conception, suggesting disengagement from care

TNOs are Cool: A survey of the trans-Neptunian region V. Physical characterization of 18 Plutinos using Herschel PACS observations

We present Herschel PACS photometry of 18 Plutinos and determine sizes and albedos for these objects using thermal modeling. We analyze our results for correlations, draw conclusions on the Plutino size distribution, and compare to earlier results. Flux densities are derived from PACS mini scan-maps using specialized data reduction and photometry methods. In order to improve the quality of our results, we combine our PACS data with existing Spitzer MIPS data where possible, and refine existing absolute magnitudes for the targets. The physical characterization of our sample is done using a thermal model. Uncertainties of the physical parameters are derived using customized Monte Carlo methods. The correlation analysis is performed using a bootstrap Spearman rank analysis. We find the sizes of our Plutinos to range from 150 to 730 km and geometric albedos to vary between 0.04 and 0.28. The average albedo of the sample is 0.08 \pm 0.03, which is comparable to the mean albedo of Centaurs, Jupiter Family comets and other Trans-Neptunian Objects. We were able to calibrate the Plutino size scale for the first time and find the cumulative Plutino size distribution to be best fit using a cumulative power law with q = 2 at sizes ranging from 120-400 km and q = 3 at larger sizes. We revise the bulk density of 1999 TC36 and find a density of 0.64 (+0.15/-0.11) g cm-3. On the basis of a modified Spearman rank analysis technique our Plutino sample appears to be biased with respect to object size but unbiased with respect to albedo. Furthermore, we find biases based on geometrical aspects and color in our sample. There is qualitative evidence that icy Plutinos have higher albedos than the average of the sample.Comment: 18 pages, 8 figures, 8 tables, accepted for publication in A&

Ressenyes

Index de les obres ressenyades: Alice BARTHEZ, Famille, travail et agricultur

Aula d'Ecologia : cicle de conferències 2004 /

Descripció del recurs: 13 juny 200

Air pollution and risk of lung cancer in a prospective study in Europe

To estimate the relationship between air pollution and lung cancer, a nested case-control study was set up within EPIC (European Prospective Investigation on Cancer and Nutrition). Cases had newly diagnosed lung cancer, accrued after a median follow-up of 7 years among the EPIC ex-smokers (since at least 10 years) and never smokers. Three controls per case were matched. Matching criteria were gender, age (+/-5 years), smoking status, country of recruitment and time elapsed between recruitment and diagnosis. We studied residence in proximity of heavy traffic roads as an indicator of exposure to air pollution. In addition, exposure to air pollutants (NO(2), PM10, SO(2)) was assessed using concentration data from monitoring stations in routine air quality monitoring networks. Cotinine was measured in plasma. We found a nonsignificant association between lung cancer and residence nearby heavy traffic roads (odds ratio = 1.46, 95% confidence interval, CI, 0.89-2.40). Exposure data for single pollutants were available for 197 cases and 556 matched controls. For NO(2) we found an odds ratio of 1.14 (95% CI, 0.78-1.67) for each increment of 10 microg/m(3), and an odds ratio of 1.30 (1.02-1.66) for concentrations greater than 30 microg/m(3). The association with NO(2) did not change after adjustment by cotinine and additional potential confounders, including occupational exposures. No clear association was found with other pollutants

The <i>Castalia</i> mission to Main Belt Comet 133P/Elst-Pizarro

We describe Castalia, a proposed mission to rendezvous with a Main Belt Comet (MBC), 133P/Elst-Pizarro. MBCs are a recently discovered population of apparently icy bodies within the main asteroid belt between Mars and Jupiter, which may represent the remnants of the population which supplied the early Earth with water. Castalia will perform the first exploration of this population by characterising 133P in detail, solving the puzzle of the MBC’s activity, and making the first in situ measurements of water in the asteroid belt. In many ways a successor to ESA’s highly successful Rosetta mission, Castalia will allow direct comparison between very different classes of comet, including measuring critical isotope ratios, plasma and dust properties. It will also feature the first radar system to visit a minor body, mapping the ice in the interior. Castalia was proposed, in slightly different versions, to the ESA M4 and M5 calls within the Cosmic Vision programme. We describe the science motivation for the mission, the measurements required to achieve the scientific goals, and the proposed instrument payload and spacecraft to achieve these