Scanning thermal microscopy and Raman analysis of bulk fused silica exposed to low-energy femtosecond laser pulses

Low energy femtosecond laser pulses locally increase the refractive index and the hydro-fluoric acid etching rate of fused silica. These phenomena form the basis of a direct-write method to fabricate integrated glass devices that are of particular interest for optofluidics and optomechanical applications. Yet the underlying physical mechanism behind these effects remains elusive, especially the role of the laser polarization. Using Scanning Thermal Microscope and Raman spectrometer we observe in laser affected zones, a localized sharp decrease of the thermal conductivity correlated with an increased presence of low-number SiO2 cycles. In addition, we find that a high correlation exists between the amount of structural changes and the decrease of thermal conductivity. Furthermore, sub-wavelength periodic patterns are detected for high peak power exposures. Finally, our findings indicate that, to date, the localized densification induced by femtosecond laser pulses remains well below the theoretical value achievable in mechanically densified silica

Towards a femtosecond laser micro-machined optofluidic device for distinguishing algae species

We demonstrate a small device with a microfluidic channel and an integrated waveguide as a compact rudimentary tool for the detection, real-time monitoring, and potentially classification of algae. In order to reduce parasitic noise the micro-device used a curved subsurface optical waveguide to illuminate particles transiting through a microfluidic channel. The changes in the transmitted signal are monitored using a quadrant-cell photo-detector. The signals wavelets from the different quadrants are used to qualitatively distinguish different families of algae. Additional information, such as flow direction, is also provided. The channel and waveguide are fabricated out of a monolithic fused-silica substrate using a femtosecond laser-writing process combined with chemical etching. This proof-of-concept device paves the way for more elaborate femtosecond laser-based optofluidic micro-instruments incorporating waveguide network designed for the real-time analysis of cells and microorganisms in the field

H3-receptor regulation of vascular gastrin and somatostatin releases by the isolated rat stomach.

We have studied the effects of the H3-receptor agonist (R) alpha-methylhistamine [(R) alpha-MeHA] and the H3-receptor antagonist thioperamide (Thiop) on basal- and carbachol-stimulated vascular gastrin release (GR) and somatostatin release (SR) by the isolated rat stomach. Carbachol dose-dependently stimulated and inhibited GR and SR, respectively. Maximal stimulation of GR (500 +/- 112 percent of basal; p < .01), and maximal inhibition of SR (-62 +/- 9 percent under basal; p < .01) were obtained with 1 micron carbachol. Neither (R)alpha-MeHA nor Thiop, up to 10 microns, affected GR. However, SR was dose-dependently enhanced by Thiop (25 +/- 8 percent for 10 microns). Carbachol stimulation of GR was strongly inhibited by Thiop (30 +/- 7 percent for 100 nM and 73 +/- 14 percent for 1 microgram), whereas it was potentiated by (R)alpha-MeHA. Carbachol inhibition of SR was reversed by Thiop and (R)alpha-MeHA. However, the reversal effect of (R)alpha-MeHA was prevented by the CCKB/gastrin receptor antagonist PD134308. These results support H3-receptor regulation of basal and cholinergically-stimulated GR and SR

Distribution and frequency of kdr mutations within Anopheles gambiae s.l. populations and first report of the ace.1 G119S mutation in Anopheles arabiensis from Burkina Faso (West Africa).

Published onlineJournal ArticleResearch Support, Non-U.S. Gov'tAn entomological survey was carried out at 15 sites dispersed throughout the three eco-climatic regions of Burkina Faso (West Africa) in order to assess the current distribution and frequency of mutations that confer resistance to insecticides in An. gambiae s.l. populations in the country. Both knockdown (kdr) resistance mutation variants (L1014F and L1014S), that confer resistance to pyrethroid insecticides, were identified concomitant with the ace-1 G119S mutation confirming the presence of multiple resistance mechanisms in the An. gambiae complex in Burkina Faso. Compared to the last survey, the frequency of the L1014F kdr mutation appears to have remained largely stable and relatively high in all species. In contrast, the distribution and frequency of the L1014S mutation has increased significantly in An. gambiae s.l. across much of the country. Furthermore we report, for the first time, the identification of the ace.1 G119S mutation in An. arabiensis populations collected at 8 sites [corrected]. This mutation, which confers resistance to organophosphate and carbamate insecticides, has been reported previously only in the An. gambiae S and M molecular forms. This finding is significant as organophosphates and carbamates are used in indoor residual sprays (IRS) to control malaria vectors as complementary strategies to the use of pyrethroid impregnated bednets. The occurrence of the three target-site resistance mutations in both An. gambiae molecular forms and now An. arabiensis has significant implications for the control of malaria vector populations in Burkina Faso and for resistance management strategies based on the rotation of insecticides with different modes of action.National Malaria Control Program (NMCP) of Burkina Fas

Caractérisation des systèmes de production à base de riz pluvial strict dans les exploitations agricoles de la zone Sud-soudanienne du Burkina Faso

Au Burkina Faso, le riz occupe la 4ème place des céréales tant du point de vue des superficies, de la production que de la consommation annuelle par habitant.  Cependant, la production nationale est faible et ne couvre que 47% des besoins des populations. Au Burkina trois, types de rizicultures se côtoient ; la riziculture pluviale ; la riziculture de bas-fond et la riziculture irriguée. La riziculture pluviale  offre un fort potentiel mais est mal maîtrisée avec de faibles rendements. Cette étude a été conduite sous forme d’enquête auprès de 157 producteurs afin  d’identifier les potentiels et les contraintes de la riziculture pluviale dans la zone  Ouest du Burkina. Les résultats montrent une récente introduction de la riziculture pluviale dans la zone. La superficie individuelle moyenne est de 0,81 ha. Les  rendements moyens sont d’environ 1075 kg/ha. Les quantités d’engrais par hectare sont faibles et sont en moyenne de 44,5 kg pour l’azote, 25,5 kg pour le phosphore et 15,5 kg pour le potassium. Le riz pluvial est cultivé en pure sans rotation régulière. La faible maîtrise de l’itinéraire technique de production nécessite une formation des producteurs pour accroître les rendements et booster la production du riz pluvial.© 2015 International Formulae Group. All rights reserved.Mots clés : Riz pluvial, rendement, enquêtes, itinéraire technique

Effet des précédents culturaux et de différents niveaux d’azote sur la productivité du riz pluvial strict sur sols ferrugineux tropicaux de la zone sudsoudanienne du Burkina Faso

L’azote constitue un élément essentiel dans la nutrition minérale du riz. Au Burkina Faso, le riz pluvial entre de plus en plus dans les assolements. Cependant, le  rendement du riz pluvial reste largement en deçà du potentiel des variétés. Afin de contribuer à une meilleure connaissance de la nutrition minérale du riz pluvial, un dispositif expérimental en split plot a été mis en place en station de recherche de Farako-Bâ en 2013 et 2014 pour évaluer l’effet des rotations et de la fertilisation azotée sur le rendement. Les résultats montrent que les meilleurs précédents du riz pluvial sont les légumineuses niébé et arachide. Ces deux précédents permettent un gain de rendements respectivement de 104% et 92% par rapport à la  monoculture du riz. La dose de 90 kg N/ha a permis d’obtenir le rendement paddy le plus élevé soit une augmentation de 395% par rapport à la dose sans apport d’azote 0 kg N/ha et le poids de 1000 grains le plus élevé. Cependant la dose agronomique la plus efficace quel que soit le précédent cultural est de 60 kg N/ha. Les rotations et les doses d’azote ont un effet sur l’augmentation des rendements du riz paddy en culture pluviale.© 2015 International Formulae Group. All rights reserved.Mots clés: Riz pluvial, rotations, azote, légumineuses, Burkina Faso. Effect of previous crops and different nitrogen levels on the productivity of upland  rice on ferruginous tropical soils of the South Sudan region of  Burkina FasoNitrogen is an essential element in the mineral nutrition of rice. In Burkina Faso, more and more, upland rice enters in the crop rotation. However, the yield of upland rice remains under the potential of varieties. To contribute to a better understanding of the mineral nutrition of upland rice, an experimental split plot was tested in Farako-Bâ research station in 2013 and 2014. This was to evaluate the effect of crop rotations and the effect of nitrogen fertilization on yield of upland rice. The results show that the best previous crops of upland rice are legumes, cowpea and peanut. Both previous crops allow a gain of respectively 104% and 92% of yields compared to rice monoculture. The dose of 90 kg N/ha permitted to have highest paddy yield and an increase of 395% compared to the dose without nitrogen 0 kg N/ha and the highest weight of 1000 grains. However, the most effective agronomic dose regardless of the previous crop is obtained with the dose of 60 kg N/ha. Crops rotation and nitrogen level have an effect on upland rice yield.© 2015 International Formulae Group. All rights reserved.Keywords: Upland rice, rotations, nitrogen, legumes, Burkina Faso

At Our Own Peril: DoD Risk Assessment in a Post-Primacy World

The U.S. Department of Defense (DoD) faces persistent fundamental change in its strategic and operating environments. This report suggests this reality is the product of the United States entering or being in the midst of a new, more competitive, post-U.S. primacy environment. Post-primacy conditions promise far-reaching impacts on U.S. national security and defense strategy. Consequently, there is an urgent requirement for DoD to examine and adapt how it develops strategy and describes, identifies, assesses, and communicates corporate-level risk. This report takes on the latter risk challenge. It argues for a new post-primacy risk concept and its four governing principles of diversity, dynamism, persistent dialogue, and adaptation. The authors suggest that this approach is critical to maintaining U.S. military advantage into the future. Absent change in current risk convention, the report suggests DoD exposes current and future military performance to potential failure or gross under-performance.https://press.armywarcollege.edu/monographs/1410/thumbnail.jp

Restoration of Degraded Lands in West Africa Sahel: Review of experiences in Burkina Faso and Niger

This is a comprehensive literature review of land restoration activities in West Africa Sahel. Water constraints and the inherent soil poverty are the major factors that limit crop yields and productivity of cropping systems in West Africa Sahel (WAS). Livestock is not well integrated with agricultural activities and crop residues are usually exported from the farm for household needs and animal feeding. In traditional systems, soil fertility maintenance was based on a relatively long fallow period (10-15 years) followed by a short cropping period of 3 to 5 years. But the increased population pressure has resulted in significant changes of the traditional bushfallow system. Lands are now continuously cultivated for long period with low external inputs, leading to soil fertility decline over time (Bationo and Mokwunye 1991; Bekunda et al. 2010). In addition to biophysical aspects, a wide range of socio-economic factors such as the low financial capacities of poor farmers to invest in agricultural inputs, high pressure on ecological resources for food, fodder or energy, also add to the stress on the systems. Failure by the smallholder farmers to intensify agricultural production in a manner that maintains soil productivity is the main cause of land degradation, particularly in the fragile ecosystems of WAS. Land degradation is defined as a process that leads to the reduction of land productivity for useful purposes, and is typically a result of soil, wind, or water erosion; soil salinization; waterlogging; chemical deterioration; or any combination of these factors (Adeel 2003). Land degradation is a global problem, particularly in the dry areas, home to a large population of poor farmers, where land degradation and water scarcity are major threats to food security. The impacts of land degradation are severe on both human society and ecosystems. Desertification is often wrongly attributed solely to droughts, but it is the deadly combination of continued land abuse during periods of deficient rainfall that results in unproductive land, and ultimately desertification (UNESCO 2003). Combating desertification by rehabilitating degraded lands can be done successfully, using existing, often traditional techniques. Land restoration involves restoring the fertility of degraded lands. The social syndrome where diminishing availability of lands, inherent low fertility, continuous soil erosion, and continuous nutrient removal without replenishment, results in a spiraling downfall in productive capacity and a diminished resilience of the soil system to provide a suitable medium for crop growth needs to be addressed. Smallholder farmers are at the center of both soil fertility decline and restoration process. Their decisions to manage, to utilize technologies and to improve or restore soil fertility are guided by the socioeconomic conditions and the overall benefits that will accrue from production (Sanginga and Woomer, 2009; Bekunda et al. 2010). A sustainable management of lands under cultivation and the restoration of degraded lands could be achieved by affordable strategic management innovations; taking into account the socioeconomic conditions of farmers. While individual technologies can contribute; a more integrated systems that combines technologies, crops, and trees such as the agroforestry systems could better contribute for sustainable management of natural resources. Many efforts have been invested to developing strategies and approaches for both sustainable management of natural resources and restoration of degraded lands in WAS. In some cases, farmer communities have developed sound, sustainable approaches to land rehabilitation and management but there is insufficient information on successful restoration in the context of WAS, particular with regards to policy, institutions and socioeconomic conditions under which specific approaches could be adapted and applied successfully (Bunning 2003). The main objective of this review was to investigate the main experiences of regenerating degraded landscapes (RDL) in Niger. Going through the documentation, we found many similarities in experiences across the two countries of Niger and Burkina. Some interesting experiences were found in Burkina, Niger or at the same time in the two countries. We finally decided to extend the review to the two countries as a representative zone of the WAS. The critical issue in taking restoration to scale is that ecological, economic and institutional context varies at fine scales. The main goal of this review is to identify the specificities and the context of the most efficient experiences of RDL that could be widely scaled in the WAS

Mutagenic Effects of Gamma Radiation on Eight Accessions of Cowpea (Vigna unguiculata

Abstract Mutagenesis is used for creating new genetic variability in cultivar improvement. Optimal mutagenic treatment is required for effective mutation induction in crop species. Therefore, radiosensitivity of cowpea accessions to gamma irradiation was investigated. Seeds of eight cowpea accessions were irradiated with 60 Co gamma radiation doses of 100, 200, 300, 400 and 500 Gy. The seeds were sown in pots to evaluate the treatment effects on seed germination (SG), seedling survival (SS) and growth habits of M1 generation. Data were analyzed using descriptive statistics. Low rates of SG (10% -45%) were recorded at higher doses (500 -400 Gy) in Ife Brown (IB) and its derivatives, whereas high SG rates (74% -94%) were observed in IT90K-284-2 across all treatments. Percentage SS was inversely related to gamma dosage. A wide range of LD50 for SG (329 -1054 Gy) and SS (149 -620 Gy) were observed across the cowpea accessions. Low LD50 scores for SG (329 -516 Gy) and SS (149 -357 Gy) were observed among cowpea with rough seed coat, whereas cowpea with smooth seed coat recorded higher LD50 for SG (521 and 1054 Gy) and SS (449 and 620 Gy). Seed germination LD50 and SS LD50 were highly correlated with mean coat thickness (0.899 and 0.937) than mean seed weight (0.621 and 0.678). Gamma irradiation of cowpea seed at low dosage (100 Gy) increased the vigor of M1 seedlings with respect to primary leaf area, terminal leaflet area, seedling height and plant height at six weeks. Doses of 200 Gy and above resulted in a progressive reduction in vigor of plant and seed setting of cowpea. Radio-sensitivity varied with cowpea genotype and was associated with seed testa texture, thickness and seed weight. Low gamma * Corresponding author. F. O. Olasupo et al. 340 irradiation treatment (100 Gy) may be used to enhance seedling vigor, vegetative growth and yield of cowpea at M1 generation