We report first white-light interferograms obtained with an integrated optics beam combiner on a glass plate. These results demonstrate the feasability of single-mode interferometric beam combination ...with integrated optics technology presented and discussed in paper I. The demonstration is achieved in laboratory with off-the-shelves components coming from micro-sensor applications, not optimized for astronomical use. These two-telescope beam combiners made by ion exchange technique on glass substrate provide laboratory white-light interferograms simultaneously with photometric calibration. A dedicated interferometric workbench using optical fibers is set up to characterize these devices. Despite the rather low match of the component parameters to astronomical constraints, we obtain stable contrasts higher than 93% with a 1.54-\micron laser source and up to 78% with a white-light source in the astronomical H band. Global throughput of 27% for a potassium ion exchange beam combiner and of 43% for a silver one are reached. This work validates our approach for combining several stellar beams of a long baseline interferometer with integrated optics components.
We report the first spatially-resolved observations of the spectroscopic binaries lambda Vir and WR 140, which includes the debut of aperture-synthesis imaging with the upgraded three-telescope IOTA ...interferometer. Using IONIC-3, a new integrated optics beam combiner capable of precise closure phase measurement, short observations were sufficient to extract the angular separation and orientation of each binary system and the component brightness ratio. Most notably, the underlying binary in the prototypical colliding-wind source WR 140 (WC7 + O4/5) was found to have a separation of ~13 milli-arcseconds with a position angle consistent with the images of the 2001 dust shell ejection only if the Wolf-Rayet star is fainter than the O star at 1.65 microns. We also highlight lambda Vir whose peculiar stellar properties of the Am star components will permit direct testing of current theories of tidal evolution when the full orbit is determined.
In this work, we present the first AMBER observations, of the Wolf-Rayet and O (WR+O) star binary system y2 Velorum. The AMBER instrument was used with the telescopes UT2, UT3, and UT4 on baselines ...ranging from 46m to 85m. It delivered spectrally dispersed visibilities, as well as differential and closure phases, with a resolution R = 1500 in the spectral band 1.95-2.17 micron. We interpret these data in the context of a binary system with unresolved components, neglecting in a first approximation the wind-wind collision zone flux contribution. We show that the AMBER observables result primarily from the contribution of the individual components of the WR+O binary system. We discuss several interpretations of the residuals, and speculate on the detection of an additional continuum component, originating from the free-free emission associated with the wind-wind collision zone (WWCZ), and contributing at most to the observed K-band flux at the 5% level. The expected absolute separation and position angle at the time of observations were 5.1±0.9mas and 66±15° respectively. However, we infer a separation of 3.62+0.11-0.30 mas and a position angle of 73+9-11°. Our analysis thus implies that the binary system lies at a distance of 368+38-13 pc, in agreement with recent spectrophotometric estimates, but significantly larger than the Hipparcos value of 258+41-31 pc.
Abstract Although developmental exposures of rats to low levels of the organophosphate pesticides (OPs), chlorpyrifos (CPF) or diazinon (DZN), both cause persistent neurobehavioral effects, there are ...important differences in their neurotoxicity. The current study extended investigation to parathion (PTN), an OP that has higher systemic toxicity than either CPF or DZN. We gave PTN on postnatal days (PND) 1–4 at doses spanning the threshold for systemic toxicity (0, 0.1 or 0.2 mg/kg/day, s.c.) and performed a battery of emotional and cognitive behavioral tests in adolescence through adulthood. The higher PTN dose increased time spent on the open arms and the number of center crossings in the plus maze, indicating greater risk-taking and overall activity. This group also showed a decrease in tactile startle response without altering prepulse inhibition, indicating a blunted acute sensorimotor reaction without alteration in sensorimotor plasticity. T-maze spontaneous alternation, novelty-suppressed feeding, preference for sweetened chocolate milk, and locomotor activity were not significantly affected by neonatal PTN exposure. During radial-arm maze acquisition, rats given the lower PTN dose committed fewer errors compared to controls and displayed lower sensitivity to the amnestic effects of the NMDA receptor blocker, dizocilpine. No PTN effects were observed with regard to the sensitivity to blockade of muscarinic and nicotinic cholinergic receptors, or serotonin 5HT2 receptors. This study shows that neonatal PTN exposure evokes long-term changes in behavior, but the effects are less severe, and in some incidences opposite in nature, to those seen earlier for CPF or DZN, findings consistent with our neurochemical studies showing different patterns of effects and less neurotoxic damage with PTN. Our results reinforce the conclusion that low dose exposure to different OPs can have quite different neurotoxic effects, obviously unconnected to their shared property as cholinesterase inhibitors.
During Galileo's orbit G2 in 1996 the Energetic Particles Detector (EPD) onboard the spacecraft detected a number of particle bursts with large radial/antisunward anisotropies in the distant Jovian ...magnetotail Krupp et al., 1998. In this letter we focus on a detailed analysis of one of the bursts. Prior to the onset of the burst, particle intensities at low energies increase over several hours. This phase can be interpreted as a plasma loading phase. It ends after the onset of strong distortions in the magnetic field with a bipolar excursion of the north‐south component being the most prominent feature. The subsequent plasma sheet encounters show that the plasma sheet has thinned considerably. Accelerated/heated ion beams first from the Jovian direction and then later from the tail direction are seen at the plasma sheet and lobe interfaces and intense radio and plasma wave emissions are detected. The event is tentatively interpreted as a dynamical process, where the Jovian magnetotail is internally driven unstable by mass loading of magnetic flux tubes.
Malaria remains a major health problem in sub- Saharan African countries despite substantial decreases in morbidity and mortality due to sustained control programs. Vaccines candidates were mainly ...tested in rural endemic setting; however increasing proportion of the population is living in urban area. Evaluation of the qualitative or quantitative immune responses to key targets of anti-Plasmodium immunity requires further investigation in urban area. In a cohort of 144 patients with mild malaria living in Dakar, we analyzed IgG responses against target antigens of P. falciparum: CSP, LSA-3NR2 and GLURP by ELISA. A mean age of 15 yrs (4-65 yrs) was found and patients were separated in 59 adults (<15yrs) and 85 children (≤15 yrs). Parasites densities (0,01-15%) did not differ between the two age groups. In contrast, haemoglobin levels appeared lower in children (4.5-16.6 g/dl) (p<0.01). For the immune results, the most recognized antigens were GLURP and CSP compared to LSA-3NR2. Levels of IgG against these antigens were significantly different between the two age groups and they were positively correlated (rho = 0.32; p<0.001). In addition, levels of IgG anti-GLURP were associated with low parasitemia (≤1%) and absence of anemia (≥11g/dl), particularly in adults (p<0.001). In a multiple regression analysis, no significant relationship was found between parasite densities and IgG responses against all the tested antigens. Our study shows the implication of IgG anti-GLURP in humoral immune response against the parasite. The present work contributes to determine IgG levels that can be used as relevant immunologic biomarkers in urban clinical malaria.
Résumé
Plusieurs candidats vaccins contre le paludisme à
Plasmodium falciparum
sont à diverses phases d’essais cliniques en zone rurale à forte endémicité palustre. Très peu d’études ont concerné les ...grandes villes. L’urbanisation rapide des populations africaines requiert la poursuite des investigations concernant le paludisme dans ces villes. Cette étude a consisté en une évaluation par ELISA des taux d’IgG dirigées contre les antigènes CSP, LSA-3NR2 et GLURP de
P. falciparum
. Elle a été faite chez 144 patients dakarois consultant pour un accès palustre (non aggravé). L’âge moyen était de 15 ans (4-65). Les patients étaient répartis en 59 adultes (< 15 ans) et 85 enfants (≤ 15 ans). Les parasitémies allant de 0,01 à 15 %, n’étaient pas variables suivant l’âge contrairement aux taux d’hémoglobine (4,5-16,6 g/dl) plus faibles chez les enfants (
p
< 0,01). Au plan immunologique, GLURP et CSP étaient plus reconnus que LSA- 3NR2. Les taux d’IgG anti-GLURP et anti-CSP sont apparus discriminants suivant l’âge avec globalement une corrélation positive (
rho
= 0,32;
p
< 0,001). Seuls les niveaux d’IgG anti-GLURP étaient associés aux faibles parasitémies (≤ 1 %) et aux taux élevés d’hémoglobinémie (≥ 11 g/dl), surtout chez les adultes (
p
< 0,001). Dans une analyse de régression multiple, aucune des réponses contre les antigènes testés n’a été associée aux parasitémies. Nos résultats montrent l’implication des IgG anti-GLURP dans l’immunité humorale antiparasitaire. L’apport de ce travail est d’avoir contribué à déterminer des niveaux d’IgG pouvant servir de biomarqueurs du statut clinique dans le paludisme urbain.
Drug resistance to Plasmodium falciparum contributes to major health problems in central Africa and, as a consequence, poverty. We have analyzed the efficacy of three currently available antimalarial ...drugs to treat symptomatic, uncomplicated P. falciparum malaria in semiimmune adults living in Bangui, Central Republic of Africa. 210 consecutive individuals were enrolled in the survey, of which 45 were excluded. Those having received dihydroartemisin proved significantly less parasitemic than those having received quinine per os or sulfadoxin-pyrimethamin (χ2 = 16.93 ; p < 0.05), and 75 % recovered in two days compared to 57 and 44 %, respectively. The 25 % who did not recover benefited from a second cure with dihydroartemisin, which proved 100 % efficient. The most accurate protocol remains to be established by analyzing clinical and parasitological data and taking into account the economics of the country.
La résistance de Plasmodium falciparum aux traitements est à l’origine de problèmes de santé majeurs en Afrique Centrale, qui ont pour conséquence la pauvreté. Nous avons analysé l’efficacité de trois médicaments disponibles actuellement afin de traiter le paludisme symptomatique, mais non compliqué, chez des adultes partiellement immunisés vivant à Bangui (RCA). 210 individus différents ont pris part à cette étude. Ceux qui avaient reçu de la dihydroartémisine ont été significativement moins parasitémiques que ceux ayant reçu de la quinine orale ou de la sulfadoxine-pyriméthamine : et 75 % des patients ont guéri en deux jours vs 57 % et 44 % respectivement. Les 25 % qui n’ont pas guéri ont reçu un deuxième traitement de dihydroartémisine qui s’est révélé efficace à 100 %. Un protocole adapté doit être mis au point en analysant des données cliniques et parasitologiques, et en tenant compte de l’économie du pays.
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