109 research outputs found
Feed Intake, Digestibility and Growth Performance of Horro Lambs Fed Natural Pasture Hay Supplemented Graded Level of Vernonia amygdalina Leaves and Sorghum Grain Mixture
No Abstract
Fast and stable gratings inscription in POFs made of different materials with pulsed 248 nm KrF laser
"© 2018 Optical Society of America. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited"[EN] This paper presents fiber Bragg grating (FBG) inscription with a pulsed 248 nm UV KrF laser in polymer optical fibers (POFs) made of different polymers, namely polymethyl methacrylate (PMMA), cyclic-olefin polymer and co-polymer, and Polycarbonate. The inscribed gratings and the corresponding inscription parameters are compared with grating inscribed in POFs made of the aforementioned materials but with the hitherto most used laser for inscription, which is a continuous wave 325 nm UV HeCd laser. Results show a reduction of the inscription time of at least 16 times. The maximum time reduction is more than 130 times. In addition, a reflectivity and a bandwidth close to or higher than the ones with the 325 nm laser were obtained. The polymer optical fiber Bragg gratings (POFBGs) inscribed with the 248 nm laser setup present high stability with small variations in their central wavelength, bandwidth, and reflectivity after 40 days. (c) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.Fundacao para Ciencia e a Tecnologia (FCT) (SFRH/BPD/109458/2015, UID/EEA/50008/2013).Marques, C.; Min, R.; Leal-Junior, A.; Antunes, P.; Fasano, A.; Woyessa, G.; Nielsen, K.... (2018). Fast and stable gratings inscription in POFs made of different materials with pulsed 248 nm KrF laser. Optics Express. 26(2):2013-2022. https://doi.org/10.1364/OE.26.002013S20132022262Webb, D. J. (2015). Fibre Bragg grating sensors in polymer optical fibres. Measurement Science and Technology, 26(9), 092004. doi:10.1088/0957-0233/26/9/092004Prado, A. R., Leal-Junior, A. G., Marques, C., Leite, S., de Sena, G. L., Machado, L. C., … Pontes, M. J. (2017). Polymethyl methacrylate (PMMA) recycling for the production of optical fiber sensor systems. Optics Express, 25(24), 30051. doi:10.1364/oe.25.030051Hu, X., Saez-Rodriguez, D., Marques, C., Bang, O., Webb, D. J., Mégret, P., & Caucheteur, C. (2015). Polarization effects in polymer FBGs: study and use for transverse force sensing. Optics Express, 23(4), 4581. doi:10.1364/oe.23.004581Pospori, A., Marques, C. A. F., Bang, O., Webb, D. J., & André, P. (2017). Polymer optical fiber Bragg grating inscription with a single UV laser pulse. Optics Express, 25(8), 9028. doi:10.1364/oe.25.009028Marques, C. A. F., Webb, D. J., & Andre, P. (2017). Polymer optical fiber sensors in human life safety. Optical Fiber Technology, 36, 144-154. doi:10.1016/j.yofte.2017.03.010Fasano, A., Woyessa, G., Janting, J., Rasmussen, H. K., & Bang, O. (2017). Solution-Mediated Annealing of Polymer Optical Fiber Bragg Gratings at Room Temperature. IEEE Photonics Technology Letters, 29(8), 687-690. doi:10.1109/lpt.2017.2678481Woyessa, G., Pedersen, J. K. M., Fasano, A., Nielsen, K., Markos, C., Rasmussen, H. K., & Bang, O. (2017). Zeonex-PMMA microstructured polymer optical FBGs for simultaneous humidity and temperature sensing. Optics Letters, 42(6), 1161. doi:10.1364/ol.42.001161Fasano, A., Woyessa, G., Stajanca, P., Markos, C., Stefani, A., Nielsen, K., … Bang, O. (2016). Fabrication and characterization of polycarbonate microstructured polymer optical fibers for high-temperature-resistant fiber Bragg grating strain sensors. Optical Materials Express, 6(2), 649. doi:10.1364/ome.6.000649Woyessa, G., Nielsen, K., Stefani, A., Markos, C., & Bang, O. (2016). Temperature insensitive hysteresis free highly sensitive polymer optical fiber Bragg grating humidity sensor. Optics Express, 24(2), 1206. doi:10.1364/oe.24.001206Leal-Junior, A. G., Frizera, A., & José Pontes, M. (2018). Sensitive zone parameters and curvature radius evaluation for polymer optical fiber curvature sensors. Optics & Laser Technology, 100, 272-281. doi:10.1016/j.optlastec.2017.10.006Stefani, A., Andresen, S., Yuan, W., Herholdt-Rasmussen, N., & Bang, O. (2012). High Sensitivity Polymer Optical Fiber-Bragg-Grating-Based Accelerometer. IEEE Photonics Technology Letters, 24(9), 763-765. doi:10.1109/lpt.2012.2188024Marques, C. A. F., Peng, G.-D., & Webb, D. J. (2015). Highly sensitive liquid level monitoring system utilizing polymer fiber Bragg gratings. Optics Express, 23(5), 6058. doi:10.1364/oe.23.006058Jensen, J. B., Hoiby, P. E., Emiliyanov, G., Bang, O., Pedersen, L. H., & Bjarklev, A. (2005). Selective detection of antibodies in microstructured polymer optical fibers. Optics Express, 13(15), 5883. doi:10.1364/opex.13.005883Emiliyanov, G., Høiby, P., Pedersen, L., & Bang, O. (2013). Selective Serial Multi-Antibody Biosensing with TOPAS Microstructured Polymer Optical Fibers. Sensors, 13(3), 3242-3251. doi:10.3390/s130303242Hassan, H. U., Janting, J., Aasmul, S., & Bang, O. (2016). Polymer Optical Fiber Compound Parabolic Concentrator fiber tip based glucose sensor: in-Vitro Testing. IEEE Sensors Journal, 1-1. doi:10.1109/jsen.2016.2606580Yuan, W., Khan, L., Webb, D. J., Kalli, K., Rasmussen, H. K., Stefani, A., & Bang, O. (2011). Humidity insensitive TOPAS polymer fiber Bragg grating sensor. Optics Express, 19(20), 19731. doi:10.1364/oe.19.019731Johnson, I. P., Yuan, W., Stefani, A., Nielsen, K., Rasmussen, H. K., Khan, L., … Bang, O. (2011). Optical fibre Bragg grating recorded in TOPAS cyclic olefin copolymer. Electronics Letters, 47(4), 271. doi:10.1049/el.2010.7347Markos, C., Stefani, A., Nielsen, K., Rasmussen, H. K., Yuan, W., & Bang, O. (2013). High-T_g TOPAS microstructured polymer optical fiber for fiber Bragg grating strain sensing at 110 degrees. Optics Express, 21(4), 4758. doi:10.1364/oe.21.004758Woyessa, G., Fasano, A., Stefani, A., Markos, C., Nielsen, K., Rasmussen, H. K., & Bang, O. (2016). Single mode step-index polymer optical fiber for humidity insensitive high temperature fiber Bragg grating sensors. Optics Express, 24(2), 1253. doi:10.1364/oe.24.001253Woyessa, G., Fasano, A., Markos, C., Stefani, A., Rasmussen, H. K., & Bang, O. (2016). Zeonex microstructured polymer optical fiber: fabrication friendly fibers for high temperature and humidity insensitive Bragg grating sensing. Optical Materials Express, 7(1), 286. doi:10.1364/ome.7.000286Stefani, A., Nielsen, K., Rasmussen, H. K., & Bang, O. (2012). Cleaving of TOPAS and PMMA microstructured polymer optical fibers: Core-shift and statistical quality optimization. Optics Communications, 285(7), 1825-1833. doi:10.1016/j.optcom.2011.12.033Nielsen, K., Rasmussen, H. K., Adam, A. J., Planken, P. C., Bang, O., & Jepsen, P. U. (2009). Bendable, low-loss Topas fibers for the terahertz frequency range. Optics Express, 17(10), 8592. doi:10.1364/oe.17.008592Nielsen, K., Rasmussen, H. K., Jepsen, P. U., & Bang, O. (2010). Broadband terahertz fiber directional coupler. Optics Letters, 35(17), 2879. doi:10.1364/ol.35.002879Anthony, J., Leonhardt, R., Argyros, A., & Large, M. C. J. (2011). Characterization of a microstructured Zeonex terahertz fiber. Journal of the Optical Society of America B, 28(5), 1013. doi:10.1364/josab.28.001013Woyessa, G., Fasano, A., Markos, C., Rasmussen, H. K., & Bang, O. (2017). Low Loss Polycarbonate Polymer Optical Fiber for High Temperature FBG Humidity Sensing. IEEE Photonics Technology Letters, 29(7), 575-578. doi:10.1109/lpt.2017.2668524Johnson, I. P., Kalli, K., & Webb, D. J. (2010). 827 nm Bragg grating sensor in multimode microstructured polymer optical fibre. Electronics Letters, 46(17), 1217. doi:10.1049/el.2010.1595Stefani, A., Wu Yuan, Markos, C., & Bang, O. (2011). Narrow Bandwidth 850-nm Fiber Bragg Gratings in Few-Mode Polymer Optical Fibers. IEEE Photonics Technology Letters, 23(10), 660-662. doi:10.1109/lpt.2011.2125786Hu, X., Pun, C.-F. J., Tam, H.-Y., Mégret, P., & Caucheteur, C. (2014). Highly reflective Bragg gratings in slightly etched step-index polymer optical fiber. Optics Express, 22(15), 18807. doi:10.1364/oe.22.018807Hu, X., Pun, C.-F. J., Tam, H.-Y., Mégret, P., & Caucheteur, C. (2014). Tilted Bragg gratings in step-index polymer optical fiber. Optics Letters, 39(24), 6835. doi:10.1364/ol.39.006835Sáez-Rodríguez, D., Nielsen, K., Rasmussen, H. K., Bang, O., & Webb, D. J. (2013). Highly photosensitive polymethyl methacrylate microstructured polymer optical fiber with doped core. Optics Letters, 38(19), 3769. doi:10.1364/ol.38.003769Hu, X., Woyessa, G., Kinet, D., Janting, J., Nielsen, K., Bang, O., & Caucheteur, C. (2017). BDK-doped core microstructured PMMA optical fiber for effective Bragg grating photo-inscription. Optics Letters, 42(11), 2209. doi:10.1364/ol.42.002209Statkiewicz-Barabach, G., Kowal, D., Mergo, P., & Urbanczyk, W. (2015). Comparison of growth dynamics and temporal stability of Bragg gratings written in polymer fibers of different types. Journal of Optics, 17(8), 085606. doi:10.1088/2040-8978/17/8/085606Marques, C., Pospori, A., Demirci, G., Çetinkaya, O., Gawdzik, B., Antunes, P., … Webb, D. (2017). Fast Bragg Grating Inscription in PMMA Polymer Optical Fibres: Impact of Thermal Pre-Treatment of Preforms. Sensors, 17(4), 891. doi:10.3390/s17040891Bundalo, I.-L., Nielsen, K., Markos, C., & Bang, O. (2014). Bragg grating writing in PMMA microstructured polymer optical fibers in less than 7 minutes. Optics Express, 22(5), 5270. doi:10.1364/oe.22.005270Oliveira, R., Bilro, L., & Nogueira, R. (2015). Bragg gratings in a few mode microstructured polymer optical fiber in less than 30 seconds. Optics Express, 23(8), 10181. doi:10.1364/oe.23.010181Lacraz, A., Polis, M., Theodosiou, A., Koutsides, C., & Kalli, K. (2015). Femtosecond Laser Inscribed Bragg Gratings in Low Loss CYTOP Polymer Optical Fiber. IEEE Photonics Technology Letters, 27(7), 693-696. doi:10.1109/lpt.2014.2386692Theodosiou, A., Lacraz, A., Stassis, A., Koutsides, C., Komodromos, M., & Kalli, K. (2017). Plane-by-Plane Femtosecond Laser Inscription Method for Single-Peak Bragg Gratings in Multimode CYTOP Polymer Optical Fiber. Journal of Lightwave Technology, 35(24), 5404-5410. doi:10.1109/jlt.2017.2776862Yuan, W., Stefani, A., Bache, M., Jacobsen, T., Rose, B., Herholdt-Rasmussen, N., … Bang, O. (2011). Improved thermal and strain performance of annealed polymer optical fiber Bragg gratings. Optics Communications, 284(1), 176-182. doi:10.1016/j.optcom.2010.08.069Bundalo, I.-L., Nielsen, K., Woyessa, G., & Bang, O. (2017). Long-term strain response of polymer optical fiber FBG sensors. Optical Materials Express, 7(3), 967. doi:10.1364/ome.7.00096
Investigation of acute febrile illness outbreak- Asyaita and Dupti districts, Afar Region, Ethiopia, February 2011
Spatiotemporal analysis of droughts using self-calibrating Palmer’s Drought Severity Index in the central region of South Africa
Published ArticleThe loss of life and property from drought events has forced society to focus on the development of reliable early warning systems which may enable farmers and other stakeholders to correctly and timely adapt to the expected impacts of climatic hazard. However, a scientific approach to a reliable early warning system for a region requires, among others, characterisation of drought events in the region in terms of duration, magnitude, intensity and frequency using standard drought indices. Therefore, the objective of this study was to identify and characterise drought events in the Modder River basin, central region of South Africa, using a self-calibrated Palmer’s Drought Severity Index (sc-PDSI). Attempts were also made to establish a relationship between meteorological and hydrological drought events in the region. During the period of analysis, the total number of drought episodes identified in the study area ranged between eight and sixteen. It was found that the most severe drought episodes occurred during the period 1992–1995 followed by the period 1982–1987. Results of analysis of seasonal drought events in one of the quaternary catchments (C52A) revealed that peak drought events during the three summer months (November, December and January) occurred in the area in 1993. However, in terms of event magnitude and intensity, the worst drought events were recorded during the period December 1982–July 1987, followed by the event that ensued during December 1989–September 1995. Results of analysis of decadal variation of drought events showed that the number of extreme and moderate drought events recorded in the catchment showed statistically significant increasing trends during the five decades at 5 % significance level. Moreover, spectral analysis of sc-PDSI time series in the region identified periodicities in the time series ranging from 6 years (C52E) to 16 years (C52K). In terms of the spatial extent of extreme drought events, the maximum areal coverage (91 %) was recorded in November 1998, followed by December 1998 and December–January 1999 (43 %). Analysis of the relative frequency of droughts of varying categories revealed that extreme drought events were most prevalent in the C52E (2.72 %) quaternary catchment, followed by C52C (2.21 %). The study also found an average lag time of 10 months between the onsets of meteorological and hydrological drought events in the region
3D-printed PMMA preform for hollow-core POF drawing
In this paper we report the first, to our knowledge, 3D-printed hollow-core poly(methyl methacrylate) (PMMA) preform for polymer optical fibre drawing. It was printed of commercial PMMA by means of fused deposition modelling technique. The preform was drawn to cane, proving good enough quality of drawing process and the PMMA molecular weight to be appropriate for drawing. This ascertains that the manufacturing process provides preforms suitable for hollow-core fibre drawing. The paper focuses on maximisation of transparency of PMMA 3D printouts by optimising printing process parameters: nozzle temperature, printing speed and infill
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International Research Institute for Climate and Society
The role of climate in health is currently enjoying a high profile among the international community in terms of demonstrating climate risk management and adaptation to a changing climate. The effect of climate variability and change on heath is a serious issue for most sub-Saharan African countries. Among the diseases that have public health importance in Ethiopia are malaria, meningitis and acute watery diarrhea. Understanding the relationship of climate and health in Ethiopia would be a tremendous help in early containment of these diseases.
In Ethiopia, before the establishment of a Climate and Health Working Group (CHWG), which includes the Federal Ministry of Health and the National Meteorological Agency among other partners, the sharing of information among the two key players was minimal. The goal of this working group is to create a climate-informed health sector that routinely requests and uses appropriate climate information to improve the effectiveness of health interventions. In order to meet its goals, the working group, in collaboration with the International Research Institute for Climate and Society (IRI), organized a six-day training course for health professionals on climate and health.
In this training, the Summer Institute course ‘Climate Information for Public Health’ (held for the past two years at IRI in New York), was adapted and implemented. The Summer Institute has involved four Ethiopian participants, one from the National Meteorological Agency (NMA), and three from the Ministry of Health. They played a key role in facilitating some of the course lectures themselves and in identifying local professionals who could also contribute to the curriculum.
The general goal of the six-day training was to build the national capacity in order to utilize climate information for decision-making in the health sector at national and regional state levels. The training was comprised of three components: core lectures, practical sessions, and short recap presentations by the participants.
Sixteen participants were involved in the training. The selection of the participants was done in consultation with the Federal Ministry of Health. Participants came primarily from the Public Health Emergency Management Units of regional and federal health bureaus and were chosen for their roles in the decision-making around the prevention and control of climate-sensitive diseases.
Three types of evaluation were carried out, a pre- and post-test, as well as an overall evaluation. The pre- and post-test helped to evaluate the level of knowledge about climate and health before and after the training. The latter helped in evaluating the organization of the overall training. Generally, the evaluations revealed that the training helped to increase the knowledge of the links between climate and health, as well as the use of climate information for decision-making in the public health sector.
This training is the first of its kind organized in Ethiopia, especially at a national level. Most of the participants agreed on the suitability of the content, design and delivery of the course and showed their interest in organizing similar training initiatives in their respective home institutions. It is possible to recommend that this training should be extended to the regional health bureau level, with the already trained participants taking the primary responsibility of facilitating these follow-on activities with the close support of the CHWG. The collaboration of the regional branch offices of the National Meteorological Agency, with respect to using climate information, would play a crucial role in this endeavor. The most important point is to sustain this training and update its contents accordingly. The future research agenda and evidence generation efforts of the CHWG and its members should also focus on other climate-sensitive diseases. Even though participants did not indicate there were always established ties to local universities in different parts of the country, these potential partnerships should be addressed in sharing the knowledge of the use of climate information for public health decision-making and in prioritizing locally important diseases.
The training was held at UNECA, Addis Ababa, Ethiopia, between November 31st and December 5th, 2009. Financial and technical support was provided by IRI with funding from the Google.org sponsored project “Building Capacity to Produce and Use Climate and Environmental Information for Improving Health in East Africa”
Dynamic mechanical characterization with respect to temperature, humidity, frequency and strain in mPOFs made of different materials
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Climate Variability and Change: Implications for Malaria Control and Elimination in Africa
In Ethiopia, malaria continues to be a major public health concern with an estimated
two thirds of the national population at risk of infection. Tackling a key driver, this
workshop was convened to advance the understanding of the impact of climate
variability and change in relation to the malaria burden to better inform policy
decisions related to current control and future elimination strategies. To achieve
this, the workshop explored data, methodologies and tools that could be used by
national public health researchers to improve malaria risk assessments.
The motivation for the workshop came from an NIH funded project entitled “Climate
Variability and Change: Implications for Malaria Control and Elimination in Africa”
with the goal of supporting malaria researchers in affected countries in East Africa
to identify opportunities for improving the effectiveness of prevention, control and
elimination strategies by incorporating an understanding of likely short and longer
term changes in the climate in their analysis. In particular, the workshop aimed to
address the challenge of varied drivers of the climate, acting at multiple timescales
including year to year variability, 10-20 year climate shifts and long term trends
associated with climate change.
Data sources explored during the workshop included the newly developed
Enhanced National Climate Services (ENACTS) rainfall and temperature products
disseminated by the Ethiopian National Meteorological Agency (NMA), as well as
globally available climate products freely distributed online. The Climate
Predictability Tool (CPT), developed by the International Research Institute for
Climate and Society (IRI), to assist climatologists in making robust predictions was
tested for the first time as a potential tool for the malaria research community to
assess the relationship of malaria to large-scale climate processes. In addition, a
multi-model malaria platform (MMMP) was presented during the workshop to
explore uncertainty associated with the predictability of malaria over time using a
series of process-based models
The effect of ivermectin® on fertility, fecundity and mortality of Anopheles arabiensis fed on treated men in Ethiopia.
BACKGROUND: Insecticide resistance is a growing threat to malaria vector control. Ivermectin, either administered to humans or animals, may represent an alternate strategy to reduce resistant mosquito populations. The aim of this study was to assess the residual or delayed effect of administering a single oral dose of ivermectin to humans on the survival, fecundity and fertility of Anopheles arabiensis in Ethiopia. METHODS: Six male volunteers aged 25-40 years (weight range 64-72 kg) were recruited; four of them received a recommended single oral dose of 12 mg ivermectin and the other two individuals were untreated controls. A fully susceptible insectary colony of An. arabiensis was fed on treated and control participants at 1, 4, 7, 10 and 13 days post ivermectin-administration. Daily mosquito mortality was recorded for 5 days. An. arabiensis fecundity and fertility were measured from day 7 post treatment, by dissection to examine the number of eggs per mosquito, and by observing larval hatching rates, respectively. RESULTS: Ivermectin treatment induced significantly higher An. arabiensis mortality on days 1 and 4, compared to untreated controls (p = 0.02 and p < 0.001, respectively). However, this effect had declined by day 7, with no significant difference in mortality between treated and control groups (p = 0.06). The mean survival time of mosquitoes fed on day 1 was 2.1 days, while those fed on day 4 survived 4.0 days. Mosquitoes fed on the treatment group at day 7 and 10 produced significantly lower numbers of eggs compared to the untreated controls (p < 0.001 and p = 0.04, respectively). An. arabiensis fed on day 7 on treated men also had lower larval hatching rates than mosquitoes fed on days 10 and 13 (p = 0.003 and p = 0.001, respectively). CONCLUSION: A single oral dose of ivermectin given to humans can induce mortality and reduce survivorship of An. arabiensis for 7 days after treatment. Ivermectin also had a delayed effect on fecundity of An. arabiensis that took bloodmeals from treated individuals on day 7 and 10. Additional studies are warranted using wild, insecticide-resistant mosquito populations, to confirm findings and a phase III evaluation among community members in Ethiopia is needed to determine the impact of ivermectin on malaria transmission
Ownership and use of long-lasting insecticidal nets for malaria prevention in Butajira area, south-central Ethiopia: complex samples data analysis
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