64 research outputs found
Active Debris Removal Mapping Project
Space debris discussions initiated with the start of the space age 55 years ago and have seen special interest in current years. This is due to the large increase in the number of space debris which has led to an increased threat of collision with operational space systems and of unsafe reentry.
Due to this increased interest in this area, many different methods have been proposed in recent years for mitigation and space debris removal, some of which have even secured funding from space agencies for further development. These include ground based lasers and space based systems which use electro-dynamic tethers, solar sails or inflatable components. While each method has its own pros and cons, some of these concepts seem to be more suitable for the short term and others for the long term.
This paper identifies major performance measures for space debris removal systems based on current rules and regulations and maps the performance of the ADR technologies based on these criteria. The map can help prioritize removal concepts and required technologies in order to better meet current needs
Isolement et identification de microorganismes indigĂšnes de cacaoyĂšres en cĂŽte dâivoire et mise en Ă©vidence de leurs effets antagonistes vis-Ă vis de Phytophthora palmivora, agent de la pourriture brune des cabosses.
En CĂŽte dâIvoire, avec des pertes de production qui avoisinent 60 % dans certaines rĂ©gions, la lutte contre la pourriture brune des cabosses du cacaoyer est devenue une prioritĂ©. La stratĂ©gie prĂ©conisĂ©e par la recherche est le dĂ©veloppement dâune mĂ©thode de lutte intĂ©grĂ©e, peu onĂ©reuse et compatible avec les prĂ©occupations environnementales. Lâune des approches privilĂ©giĂ©es de cette stratĂ©gie est lâutilisation des antagonistes naturels de Phytophthora sp. Dans cette optique, la biodiversitĂ© a Ă©tĂ© explorĂ©e dans lâĂ©cosystĂšme de la cacaoyĂšre. Des champignons et des bactĂ©ries ont Ă©tĂ© isolĂ©s Ă partir des sols sous cacaoyĂšres et des cabosses. Lâaction antagoniste des champignons sur P. palmivora a Ă©tĂ© Ă©valuĂ©e in vitro ainsi que la sensibilitĂ© foliaire Ă P. palmivora sur des disques de feuilles de cacaoyers en prĂ©sence des bactĂ©ries. Les rĂ©sultats montrent quâen culture mixte avec P. palmivora, des isolats de Trichoderma sp ont montrĂ© un effet fongistatique et fongicide. Une rĂ©duction significative des notes de sensibilitĂ© selon lâĂ©chelle de Blaha a Ă©tĂ© obtenue avec deux bactĂ©ries, appartenant au genre Bacillus. LâĂ©tude se poursuit avec lâĂ©valuation de lâefficacitĂ© des antagonistes naturels de Phytophthora sp en milieu rĂ©el sur le cacaoyer.In CĂŽte dâIvoire, yield losses due to Phytophthora sp. reach of about 60% in some cocoa growing areas; therefore, the control of cocoa black pod disease has become a priority. The management strategy is based on thedevelopment of an integrated control method which is cost effective and environmentally sound. The emphasis has been put on the use of natural antagonists of Phytophthora sp. Thus, the microbial biodiversity in the cocoa ecosystem has been explored. Fungi and bacteria have been isolated from pods and soil in cocoa farms. The antagonistic effects of these micro-organisms on Phytophthora sp. have been assessed in vitro. In addition, the leaf susceptibility to P. palmivora was assessed on cocoa leaf disks in the presence of the bacteria. The results showed that in a mix culture with P. palmivora, some isolates of Trichoderma sp. showed fungicidal effects. Two bacteria belonging to the genus Bacillus significantly reduced cocoa leaf susceptibility to P. palmivora. The study will continue to assess the efficacy of the potentially effective micro-organisms in the field for the control of the black pod disease.Mots clĂ©s : Cacaoyer ; pourriture brune ; Phytophthora ; Trichoderma ; antagoniste
Hidden Symmetry of the Differential Calculus on the Quantum Matrix Space
A standard bicovariant differential calculus on a quantum matrix space is considered. The principal result of this work is in observing
that the is in fact a
-module differential algebra.Comment: 5 page
Expanding Refugee Access to National Education Systems: The State of the Evidence on Enabling Factors, Constraints, and Interventions
This policy brief summarises actionable findings from the ERICC Evidence Review: Expanding Refugee Access to National Education Systems: The State of the Evidence (forthcoming) to further highlight evidence gaps and research needs. These findings may be particularly useful for government agencies, donor organisations, humanitarian and development actors, and research bodies. The policy brief describes the substantive, methodological and geographic scope of existing evidence on refugee student access to NES. It then presents findings about six global-, regional- and national-level enabling factors and constraints for refugee student access to NES: financing, education infrastructure and sector capacity, political will and support for refugee inclusion, governance and coordination arrangements, non-state actor engagement and data systems. Local and child-level risk and protective factors further influencing refugee access to NES are presented in the third section of the brief, including: gender, socioeconomic and legal status, language barriers, perceptions of education relevance, and xenophobia, gender-based violence and intolerance. The fourth section synthesises evidence on interventions used in refugee-hosting contexts to improve student access: global and regional frameworks that support refugee inclusion; double shift schools; recognition, validation and accreditation of prior learning, flexible learning programmes, and host country language acquisition; cash transfers; and school feeding. Finally, this brief presents research needs which stakeholders can prioritise to significantly improve the evidence base for (cost-)effective, inclusive and scalable interventions that enhance refugee student access to education
Mothering Here and Mothering There: International Migration and Postbirth Mental Health
Over 125,000 women immigrate to Canada yearlyâmost in their childbearing years and many having given birth before immigrating. We sought to (1) examine the background characteristics and mental health profile of women separated from their children due to migration and subsequently giving birth in Canada (âdual-country (DC) mothersâ) and (2) contrast these with those of ânon-dual-countryâ migrant mothers. Of 514 multiparous migrant women giving birth, one-fifth (18%) reported being separated from their children due to migration. Over one-third of DC mothers were living in poverty (36.0% versus 18.6%, P=0.001), and one in seven was experiencing household food insecurity (16.3% versus 7.6%, P=0.01). Over one-third had no partner (40.2% versus 11.4%, P=0.00), and nearly one-quarter reported no available support (23.1% versus 12.2%, P=0.007). Over three-quarters were asylum seekers or refugees (83.7% versus 51%, P=0.00). More DC than non-DC mothers had symptoms of postpartum depression (28.3% versus 18.6%, P=0.04), symptoms of clinical depression (23.1% versus 13.5%, P=0.02), and anxiety related to trauma (16.5% versus 9.4%, P=0.04). Results suggest that identifying DC mothers is a rapid approach to enable clinicians to target a subgroup of women needing special attention
Village Baseline Study: Site Analysis Report for Segou â Cinzana, Mali (MA0109)
The village baseline study of Tongo village in the CCAFS benchmark site of Cinzana, Mali took place from 12 to 14 July 2011. Focus group discussions were conducted separately for men and women. The village has an abundance of natural resources such as savannah, grassland, ponds, farmlands and several kinds of socio-economic infrastructure. Some of the natural resources, however, are in a state of progressive degradation due to increase in human population; indiscriminate felling of trees; clearing of forests and deforestation; lack of rainfall; drought; and animal pressure
Filling a blank on the map: 60Â years of fisheries in Equatorial Guinea
Despite a scarcity of pertinent information, it has been possible to reconstruct time series of marine fisheries catches for Equatorial Guinea from 1950 to 2010 using per capita fish consumption and population numbers for small-scale fisheries, catch rates and number of vessels for industrial fisheries and discard rates to estimate the discarded bycatch. Small-scale fisheries, industrial large-scale fisheries, domestic and legal and illegal foreign fisheries and their discards are all included. Total catches were estimated at 2.7 million tonnes over the time period considered, of which 653 000 t were caught domestically compared to 187 000 t reported by FAO. This shows that fisheries have more importance for Equatorial Guinea's food security than the official data suggest. In contrast to what is suggested by official figures, fisheries were shown to be strongly impacted by civil and political unrest; notably, they declined overall because of civil and political conflicts, socio-demographic dynamics, and a growing role of the newly discovered oil resources, which directly and indirectly threaten the food security of the people of Equatorial Guinea
Room-temperature ferromagnetism in graphite driven by 2D networks of point defects
Ferromagnetism in carbon-based materials is appealing for both applications
and fundamental science purposes because carbon is a light and bio-compatible
material that contains only s and p electrons in contrast to traditional
ferromagnets based on 3d or 4f electrons. Here we demonstrate direct evidence
for ferromagnetic order locally at defect structures in highly oriented
pyrolytic graphite (HOPG) with magnetic force microscopy and in bulk
magnetization measurements at room temperature. Magnetic impurities have been
excluded as the origin of the magnetic signal after careful analysis supporting
an intrinsic magnetic behavior of carbon. The observed ferromagnetism has been
attributed to originate from unpaired electron spins localized at grain
boundaries of HOPG. Grain boundaries form two-dimensional arrays of point
defects, where their spacing depends on the mutual orientation of two grains.
Depending on the distance between these point defects, scanning tunneling
spectroscopy of grain boundaries showed two intense split localized states for
small distances between defects (< 4 nm) and one localized state at the Fermi
level for large distances between defects (> 4 nm).Comment: 19 pages, 5 figure
Coastal Observations of Weather Features in Senegal during the AMMA SOP-3 Period
During 15 August through 30 September 2006, ground and aircraft measurements were obtained from a multi-national group of students and scientists in Senegal. Key measurements were aimed at investigating and understanding precipitation processes, thermodynamic and dynamic environmental conditions, cloud, aerosol and microphysical processes and spaceborne sensors (TRMM, CloudSat/Calipso) validation. Ground and aircraft instruments include: ground based polarimetric radar, disdrometer measurements, a course and a high-density rain gauge network, surface chemical measurements, a 10 m flux tower, broadband IR, solar and microwave measurements, rawinsonde and radiosonde measurements, FA-20 dropsonde, in situ microphysics and cloud radar measurements. Highlights during SOP3 include ground and aircraft measurements of squall lines, African Easterly Waves (AEWs), Saharan Air Layer advances into Senegal, and aircraft measurements of AEWs -- including the perturbation that became Hurricane Isaac
Deciphering the genome structure and paleohistory of _Theobroma cacao_
We sequenced and assembled the genome of _Theobroma cacao_, an economically important tropical fruit tree crop that is the source of chocolate. The assembly corresponds to 76% of the estimated genome size and contains almost all previously described genes, with 82% of them anchored on the 10 _T. cacao_ chromosomes. Analysis of this sequence information highlighted specific expansion of some gene families during evolution, for example flavonoid-related genes. It also provides a major source of candidate genes for _T. cacao_ disease resistance and quality improvement. Based on the inferred paleohistory of the T. cacao genome, we propose an evolutionary scenario whereby the ten _T. cacao_ chromosomes were shaped from an ancestor through eleven chromosome fusions. The _T. cacao_ genome can be considered as a simple living relic of higher plant evolution
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