Glacier motion estimation using SAR offset-tracking procedures

Two image-to-image patch offset techniques for estimating feature motion between satellite synthetic aperture radar (SAR) images are discussed. Intensity tracking, based on patch intensity cross-correlation optimization, and coherence tracking, based on patch coherence optimization, are used to estimate the movement of glacier surfaces between two SAR images in both slant-range and azimuth direction. The accuracy and application range of the two methods are examined in the case of the surge of Monacobreen in Northern Svalbard between 1992 and 1996. Offset-tracking procedures of SAR images are an alternative to differential SAR interferometry for the estimation of glacier motion when differential SAR interferometry is limited by loss of coherence, i.e., in the case of rapid and incoherent flow and of large acquisition time intervals between the two SAR images. In addition, an offset-tracking procedure in the azimuth direction may be combined with differential SAR interferometry in the slant-range direction in order to retrieve a two-dimensional displacement map when SAR data of only one orbit configuration are available

Experimental investigation of a coherent quantum measurement of the degree of polarization of a single mode light beam

A novel method for the direct measurement of the degree of polarization is described. It is one of the first practical implementations of a coherent quantum measurement, the projection on the singlet state. Our first results demonstrate the successful operation of the method. However, due to the nonlinear crystals used presently, its application is limited to spectral widths larger than ~8nm.Comment: 23 pages, 9 figures, submitted to Journal of Modern Optic

Urban agriculture: multi-dimensional tools for social development in poor neighbourhoods

For over 30 years, different urban agriculture (UA) experiments have been undertaken in Montreal (Quebec, Canada). The Community Gardening Program, managed by the City, and 6 collective gardens, managed by community organizations, are discussed in this article. These experiments have different objectives, including food security, socialization and education. Although these have changed over time, they have also differed depending on geographic location (neighbourhood). The UA initiatives in Montreal have resulted in the development of a centre with a significant vegetable production and a socialization and education environment that fosters individual and collective social development in districts with a significant economically disadvantaged population. The various approaches attain the established objectives and these are multi-dimensional tools used for the social development of disadvantaged populations.Depuis plus de 30 ans, différentes expériences d’AU ont été tentée à Montréal (Québec, Canada). Le programme des jardins communautaires, géré par la Ville, et 6 jardins collectifs, gérés par des organisations communautaires, sont examinés dans le cadre de cet article.  Ces expériences visent différents objectifs : accroître la sécurité alimentaire, sociabiliser, éduquer, etc. Les objectifs évoluent dans le temps mais aussi selon les quartiers. Notre étude révèle que les initiatives en AU à Montréal sont un lieu de production de légumes non négligeable, un espace pour sociabiliser et un lieu d’éducation favorisant un développement social individuel et collectif des quartiers ayant une forte présence de population économique défavorisée. Les différentes approches atteignent les objectifs identifiés et permettent le développement d’outils multi-facettes favorisant le développement social des populations défavorisées.Durante más de 30 años se han realizado diversos experimentos relacionados con la agricultura urbana en Montreal (Québec, Canadá). Este artículo analiza el Programa de Horticultura Comunitario, gestionado por la ciudad, y 6 huertos colectivos, gestionados por organizaciones comunitarias. Estos experimentos cuentan con objetivos diferentes, entre los que se encuentran la seguridad alimentaria, la socialización y la educación. Con el paso del tiempo estos programas han ido evolucionando. Los proyectos se diferencian según la ubicación geográfica en la que se encuentran (barrios). Las iniciativas de agricultura urbana en Montreal han conseguido el desarrollo de un centro con una importante producción hortícola, así como un contexto de socialización y educación que fomenta el desarrollo social individual y colectivo en las zonas con un importante número de población económicamente desfavorecida. The authors would like to thank Kelly Krater, Mathieu Roy and Julie Richard from Action Communiterre, Magdouda Oudjit from Maison Quartier de Villeray, Delphine Marot and Stéphane Bergeron from the ACSA, Gratia Lapointe from Nutri-Centre LaSalle, Dominique Lacroix from Bouffe-Action de Rosemont and Denis Rousseau from the collective garden La Croisée. We would also like to thank Jean-Marie Chapeau from Centraide, André Pedneault from the City of Montreal and Lucie Sauvé, Canada Chair in Environmental Education at UQAM. This article is in line with several research projects, such as those of the Canada Research Chair in environmental education, which include a research program that highlights the foundations, practices and issues involved in “the educational experience” provided in two collective urban gardens and that of the Institut des sciences de l’environnement and the City of Montreal, which are based on the community gardens program

Dietary strategies for improving iron status: balancing safety and efficacy.

In light of evidence that high-dose iron supplements lead to a range of adverse events in low-income settings, the safety and efficacy of lower doses of iron provided through biological or industrial fortification of foodstuffs is reviewed. First, strategies for point-of-manufacture chemical fortification are compared with biofortification achieved through plant breeding. Recent insights into the mechanisms of human iron absorption and regulation, the mechanisms by which iron can promote malaria and bacterial infections, and the role of iron in modifying the gut microbiota are summarized. There is strong evidence that supplemental iron given in nonphysiological amounts can increase the risk of bacterial and protozoal infections (especially malaria), but the use of lower quantities of iron provided within a food matrix, ie, fortified food, should be safer in most cases and represents a more logical strategy for a sustained reduction of the risk of deficiency by providing the best balance of risk and benefits. Further research into iron compounds that would minimize the availability of unabsorbed iron to the gut microbiota is warranted

The April 3, 2010 earthquake along the Pernicana fault (Mt. Etna - Italy): analysis of satellite and in situ ground deformation data integrated by the SISTEM approach

Etna is worldwide known as one of the most studied and monitored active volcanoes. Flank instability along the eastern and southern portion of Mt. Etna has been observed and measured thanks to geodetic networks and InSAR data analysis. The spreading area is bordered to the north by the east-west Pernicana Fault System (PFS) which dynamic is often linked with the eruptive activity, as recently observed during the 2002-2003 eruption. A seismic sequence occurred since April 2-3, 2010, along the PFS with two very shallow (a few hundred meters) mainshocks of magnitude 3.6 and 3.5. Explosions and ash emissions at the summit craters followed this swarm and culminated some days later (April 7-8). Just after the earthquake, specific GPS surveys were carried out aimed at monitoring the eastern part of the Pernicana fault, and the leveling route on the northeastern flank of the volcano was also surveyed. Trying to investigate the deformation occurred along the PFS during the events of April 3rd 2010, we performed a DInSAR (Differential Interferometric Synthetic Aperture Radar) analysis of ascending and descending Envisat, and of ascending ALOS-PALSAR images encompassing the date of the earthquake. The Envisat interferograms show very intense but local deformation on the Envisat ascending data and a low signal for the descending geometry, close to the Pernicana fault trace. This is probably due to the oblique normal/leftlateral kinematics of the PFS (as deduced also by GPS and leveling data), indeed both vertical (lowering) and horizontal (eastwards) components of motion produce a strong stretching of the LOS (Line Of Sight) distance for ascending geometry, while the two components act in opposite ways for the descending geometry, resulting in lower LOS distance variations compared to the ascending data set. We analyzed also the ALOS pair referring to 21/02/2010 – 08/04/2010 time and acquired along the ascending track number 638. The ALOS interferogram clearly show three fringes corresponding to roughly 35 cm of LOS displacement. The preliminary modeling of the interferograms agree with the seismic information (very shallow faulting, seismic moment) and show that the medium behave elastically. In order to investigate the ground deformation pattern associated with this event, an application of the novel SISTEM (Simultaneous and Integrated Strain Tensor Estimation from geodetic and satellite deformation Measurements) approach is presented here. To achieve higher accuracy and get better constraint of the 3D components of the displacements, we improved the standard formulation of SISTEM approach, based on the GPS and a single DInSAR sensor, in order to take into account all the available dataset (GPS, leveling, ascending and descending ENVISAT C-Band interferograms and the ALOS L-Band data). The 3D displacement maps obtained using the SISTEM approach well show the kinematics of the PFS, and are able to reconstruct also the ground deformation affecting the whole investigated area, defining the movements of the north-eastern flank of the volcano. These results, which provide an accurate spatial characterization of ground deformation, are hence promising for future studies aimed at improving the knowledge about the kinematics of the active faults of Mt. Etna

Serum Hepcidin Concentrations Decline during Pregnancy and May Identify Iron Deficiency: Analysis of a Longitudinal Pregnancy Cohort in The Gambia.

Background: Antenatal anemia is a risk factor for adverse maternal and fetal outcomes and is prevalent in sub-Saharan Africa. Less than half of antenatal anemia is considered responsive to iron; identifying women in need of iron may help target interventions. Iron absorption is governed by the iron-regulatory hormone hepcidin.Objective: We sought to characterize changes in hepcidin and its associations with indexes of iron stores, erythropoiesis, and inflammation at weeks 14, 20, and 30 of gestation and to assess hepcidin's diagnostic potential as an index of iron deficiency.Methods: We measured hemoglobin and serum hepcidin, ferritin, soluble transferrin receptor (sTfR), and C-reactive protein (CRP) at 14, 20, and 30 wk of gestation in a cohort of 395 Gambian women recruited to a randomized controlled trial. Associations with hepcidin were measured by using linear regression, and hepcidin's diagnostic test accuracy [area under the receiver operating characteristic curve (AUCROC), sensitivity, specificity, cutoffs] for iron deficiency at each time point was analyzed.Results: The prevalence of anemia increased from 34.6% at 14 wk of gestation to 50.0% at 20 wk. Hepcidin concentrations declined between study enrollment and 20 wk, whereas ferritin declined between 20 and 30 wk of gestation. The variations in hepcidin explained by ferritin, sTfR, and CRP declined over pregnancy. The AUCROC values for hepcidin to detect iron deficiency (defined as ferritin <15 μg/L) were 0.86, 0.83, and 0.84 at 14, 20, and 30 wk, respectively. Hepcidin was superior to hemoglobin and sTfR as an indicator of iron deficiency.Conclusions: In Gambian pregnant women, hepcidin appears to be a useful diagnostic test for iron deficiency and may enable the identification of cases for whom iron would be beneficial. Hepcidin suppression in the second trimester suggests a window for optimal timing for antenatal iron interventions. Hemoglobin does not effectively identify iron deficiency in pregnancy. This trial was registered at www.isrctn.com as ISRCTN49285450

Rapid assessment of tetanus vaccine-induced immunity in Bangladesh and the Gambia.

We have developed recombinant fragment C based rapid point of care dipstick devices to assess tetanus immunization status using plasma or whole blood. The devices demonstrated specificity of 0.90 and sensitivity of 0.90 (whole blood)/0.94 (plasma) at field sites in Bangladesh and The Gambia when compared to a commercial ELISA with the immune cut-off titer set as ≥0.1IU/mL