Mismatch between soil nutrient requirements and fertilizer applications: Implications for yield responses in Ethiopia

Lack of accurate information about soil nutrient requirements coupled with limited access to appropriate fertilizers could lead to mismatch between soil nutrient requirements and fertilizer applications. Such anomalies and mismatches are likely to have important implications for agricultural productivity. In this paper we use experimental (spectral soil analysis) data from Ethiopia to examine farmers’ response to soil nutrient deficiencies and its implications for yield responses. We find that farmers’ response to macronutrient (nitrogen and phosphorus) deficiencies is not always consistent with agronomic recommendations. For instance, we find that farmers in our sample are applying nitrogen fertilizers to soils lacking phosphorus, potentially due to lack of information on soil nutrient deficiencies or lack of access to appropriate fertilizers in rural markets. On the other hand, farmers respond to perceivably poor-quality soils and acidic soils by applying higher amount of nitrogen and phosphorus fertilizers per unit of land. We further show that such mismatches between fertilizer applications and soil macronutrient requirements are potentially yield-reducing. Those farmers matching their soil nutrient requirements and fertilizer application are likely to enjoy additional yield gains and the vice versa. Marginal yield responses associated with nitrogen (phosphorus) application increases with soil nitrogen (phosphorus) deficiency. Similarly, we find that farmers’ response to acidic soils is not yield-enhancing. These findings suggest that such mismatches may explain heterogeneities in marginal returns to chemical fertilizers and the observed low adoption rates of chemical fertilizers in sub-Saharan Africa. As such, these findings have important implications for improving input management practices and fertilizer diffusion strategies

Comparison of NIRS, laser Doppler flowmetry, photoplethysmography, and pulse oximetry during vascular occlusion challenges

© 2016 Institute of Physics and Engineering in Medicine. Monitoring changes in blood volume, blood flow, and oxygenation in tissues is of vital importance in fields such as reconstructive surgery and trauma medicine. Near infrared spectroscopy (NIRS), laser Doppler (LDF) flowmetry, photoplethysmography (PPG), and pulse oximetry (PO) contribute to such fields due to their safe and noninvasive nature. However, the techniques have been rarely investigated simultaneously or altogether. The aim of this study was to investigate all the techniques simultaneously on healthy subjects during vascular occlusion challenges. Sensors were attached on the forearm (NIRS and LDF) and fingers (PPG and PO) of 19 healthy volunteers. Different degrees of vascular occlusion were induced by inflating a pressure cuff on the upper arm. The responses of tissue oxygenation index (NIRS), tissue haemoglobin index (NIRS), flux (LDF), perfusion index (PPG), and arterial oxygen saturation (PO) have been recorded and analyzed. Moreover, the optical densities were calculated from slow varying dc PPG, in order to distinguish changes in venous blood volumes. The indexes showed significant changes (p < 0.05) in almost all occlusions, either venous or over-systolic occlusions. However, differentiation between venous and arterial occlusion by LDF may be challenging and the perfusion index (PI) may not be adequate to indicate venous occlusions. Optical densities may be an additional tool to detect venous occlusions by PPG

Population and fertility by age and sex for 195 countries and territories, 1950–2017: a systematic analysis for the Global Burden of Disease Study 2017

Background The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2017 comparative risk assessment (CRA) is a comprehensive approach to risk factor quantification that offers a useful tool for synthesising evidence on risks and risk–outcome associations. With each annual GBD study, we update the GBD CRA to incorporate improved methods, new risks and risk–outcome pairs, and new data on risk exposure levels and risk–outcome associations. Methods We used the CRA framework developed for previous iterations of GBD to estimate levels and trends in exposure, attributable deaths, and attributable disability-adjusted life-years (DALYs), by age group, sex, year, and location for 84 behavioural, environmental and occupational, and metabolic risks or groups of risks from 1990 to 2017. This study included 476 risk–outcome pairs that met the GBD study criteria for convincing or probable evidence of causation. We extracted relative risk and exposure estimates from 46 749 randomised controlled trials, cohort studies, household surveys, census data, satellite data, and other sources. We used statistical models to pool data, adjust for bias, and incorporate covariates. Using the counterfactual scenario of theoretical minimum risk exposure level (TMREL), we estimated the portion of deaths and DALYs that could be attributed to a given risk. We explored the relationship between development and risk exposure by modelling the relationship between the Socio-demographic Index (SDI) and risk-weighted exposure prevalence and estimated expected levels of exposure and risk-attributable burden by SDI. Finally, we explored temporal changes in risk-attributable DALYs by decomposing those changes into six main component drivers of change as follows: (1) population growth; (2) changes in population age structures; (3) changes in exposure to environmental and occupational risks; (4) changes in exposure to behavioural risks; (5) changes in exposure to metabolic risks; and (6) changes due to all other factors, approximated as the risk-deleted death and DALY rates, where the risk-deleted rate is the rate that would be observed had we reduced the exposure levels to the TMREL for all risk factors included in GBD 2017. Findings In 2017, 34·1 million (95% uncertainty interval [UI] 33·3–35·0) deaths and 1·21 billion (1·14–1·28) DALYs were attributable to GBD risk factors. Globally, 61·0% (59·6–62·4) of deaths and 48·3% (46·3–50·2) of DALYs were attributed to the GBD 2017 risk factors. When ranked by risk-attributable DALYs, high systolic blood pressure (SBP) was the leading risk factor, accounting for 10·4 million (9·39–11·5) deaths and 218 million (198–237) DALYs, followed by smoking (7·10 million [6·83–7·37] deaths and 182 million [173–193] DALYs), high fasting plasma glucose (6·53 million [5·23–8·23] deaths and 171 million [144–201] DALYs), high body-mass index (BMI; 4·72 million [2·99–6·70] deaths and 148 million [98·6–202] DALYs), and short gestation for birthweight (1·43 million [1·36–1·51] deaths and 139 million [131–147] DALYs). In total, risk-attributable DALYs declined by 4·9% (3·3–6·5) between 2007 and 2017. In the absence of demographic changes (ie, population growth and ageing), changes in risk exposure and risk-deleted DALYs would have led to a 23·5% decline in DALYs during that period. Conversely, in the absence of changes in risk exposure and risk-deleted DALYs, demographic changes would have led to an 18·6% increase in DALYs during that period. The ratios of observed risk exposure levels to exposure levels expected based on SDI (O/E ratios) increased globally for unsafe drinking water and household air pollution between 1990 and 2017. This result suggests that development is occurring more rapidly than are changes in the underlying risk structure in a population. Conversely, nearly universal declines in O/E ratios for smoking and alcohol use indicate that, for a given SDI, exposure to these risks is declining. In 2017, the leading Level 4 risk factor for age-standardised DALY rates was high SBP in four super-regions: central Europe, eastern Europe, and central Asia; north Africa and Middle East; south Asia; and southeast Asia, east Asia, and Oceania. The leading risk factor in the high-income super-region was smoking, in Latin America and Caribbean was high BMI, and in sub-Saharan Africa was unsafe sex. O/E ratios for unsafe sex in sub-Saharan Africa were notably high, and those for alcohol use in north Africa and the Middle East were notably low. Interpretation By quantifying levels and trends in exposures to risk factors and the resulting disease burden, this assessment offers insight into where past policy and programme efforts might have been successful and highlights current priorities for public health action. Decreases in behavioural, environmental, and occupational risks have largely offset the effects of population growth and ageing, in relation to trends in absolute burden. Conversely, the combination of increasing metabolic risks and population ageing will probably continue to drive the increasing trends in non-communicable diseases at the global level, which presents both a public health challenge and opportunity. We see considerable spatiotemporal heterogeneity in levels of risk exposure and risk-attributable burden. Although levels of development underlie some of this heterogeneity, O/E ratios show risks for which countries are overperforming or underperforming relative to their level of development. As such, these ratios provide a benchmarking tool to help to focus local decision making. Our findings reinforce the importance of both risk exposure monitoring and epidemiological research to assess causal connections between risks and health outcomes, and they highlight the usefulness of the GBD study in synthesising data to draw comprehensive and robust conclusions that help to inform good policy and strategic health plannin

Photoplethysmography for blood volumes and oxygenation changes during intermittent vascular occlusions

Photoplethysmography (PPG) is an optical technique that measures blood volume variations. The main application of dual-wavelength PPG is pulse oximetry, in which the arterial oxygen saturation (SpO[Formula: see text]) is calculated noninvasively. However, the PPG waveform contains other significant physiological information that can be used in conjunction to SpO[Formula: see text] for the assessment of oxygenation and blood volumes changes. This paper investigates the use of near infrared spectroscopy (NIRS) processing techniques for extracting relative concentration changes of oxygenated ([Formula: see text]HbO[Formula: see text]), reduced ([Formula: see text]HHb) and total haemoglobin ([Formula: see text]tHb) from dual-wavelength PPG signals during intermittent pressure-increasing vascular occlusions. A reflectance PPG sensor was attached on the left forearm of nineteen (n = 19) volunteers, along with a reference NIRS sensor positioned on the same forearm, above the left brachioradialis. The investigation protocol consisted of seven intermittent and pressure-increasing vascular occlusions. Relative changes in haemoglobin concentrations were obtained by applying the modified Beer-Lambert law to PPG signals, while oxygenation changes were estimated by the difference between red and infrared attenuations of DC PPGs (A[Formula: see text] = [Formula: see text]A[Formula: see text] - [Formula: see text]A[Formula: see text]) and by the conventional SpO[Formula: see text]. The [Formula: see text]HbO[Formula: see text], [Formula: see text]HHb, [Formula: see text]tHb from the PPG signals indicated significant changes in perfusion induced by either partial and complete occlusions (p < 0.05). The trends in the variables extracted from PPG showed good correlation with the same parameters measured by the reference NIRS monitor. Bland and Altman analysis of agreement between PPG and NIRS showed underestimation of the magnitude of changes by the PPG. A[Formula: see text] indicated significant changes for occlusion pressures exceeding 20 mmHg (p < 0.05) and correlation with tissue oxygenation changes measured by NIRS, while SpO[Formula: see text] had significant changes after 40 mmHg (p < 0.05). Relative changes in haemoglobin concentrations can be estimated from PPG signals and they showed a good level of accuracy in the detection of perfusion and oxygenation changes induced by different degrees of intermittent vascular occlusions. These results can open up to new applications of the PPG waveform in the detection of blood volumes and oxygenation changes

Age at menarche and the menstrual pattern of secondary school adolescents in northwest Ethiopia

<p>Abstract</p> <p>Background</p> <p>Population studies on normal and dysfunctional characteristics of menstrual cycles are scarce in Ethiopia. In addition variability in menarcheal age and menstrual characteristics are common. Knowledge on this variability is necessary for patient education and to guide clinical evaluation.</p> <p>Methods</p> <p>A cross sectional study was conducted in two small towns called Dabat and Kola Diba, northwest Ethiopia between April and May 2007. Systematic sampling method was used to select 622 school girls from two secondary schools. A pretested questionnaire prepared in Amharic was used to gather data. Selected girls cooperated in answering the questionnaire in their classrooms under the supervision of the research team. Only 612 of the adolescent females were included in the final analysis, of which 305 were from Koladiba High School and 307 from Dabat.</p> <p>Results</p> <p>The age of the study subjects ranges between 14 and 19 with a mean (standard deviation) of 16.9 ± 1 years. About 92.2% had attained menarche by the time the survey was conducted. The probit analysis of the <it>status quo </it>data yielded a median (CI) age at menarche of 14.8 (13.9-15.3) years. The average age at menarche by recall method was 15.8 ± 1 years. The mean age at menarche was 0.3 years younger for urban females compared with rural ones (p < 0.001). A cycle length between 21 and 35 days was observed in 70.3% of the girls. The mean duration of flow was 4 ± 1.3 days with a range of 2-7 days. The menstrual cycles were irregular in 42.8% of the subjects. The overall prevalence of dysmenorrhoea was 72% among these subjects. Premenstrual symptoms were present in 435 of the females (75.4%). The leading sources of menarcheal information to the adolescents were mothers (39.7%), followed by their friends (26.6%) and teachers (21.8%).</p> <p>Conclusion</p> <p>In this study age of menarche was found to be delayed which is even higher than the findings indicated similar studies conducted in Ethiopia and other African countries. A significant number of students complain of abnormal menstrual cycle, dysmenorrhoea and premenstrual symptoms which call for appropriate counselling and management.</p

Palladium nanoparticles supported on fluorine-doped tin oxide as an efficient heterogeneous catalyst for Suzuki coupling and 4-nitrophenol reduction

Immobilization of palladium nanoparticles onto the fluorine-doped tin oxide (FTO) as support Pd/FTO, resulted in a highly active heterogeneous catalyst for Suzuki-Miyaura cross-coupling reactions and 4-nitrophenol reduction. The Pd/FTO catalyst has been synthesized by immobilization of palladium nanoparticles onto FTO via a simple impregnation method. ICP-MS analysis confirmed that there is 0.11 mmol/g of palladium was loaded successfully on FTO support. The crystallinity, morphologies, compositions and surface properties of Pd/FTO were fully characterized by various techniques. It was further examined for its catalytic activity and robustness in Suzuki coupling reaction with different aryl halides and solvents. The yields obtained from Suzuki coupling reactions were basically over 80%. The prepared catalyst was also tested on mild reaction such as reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). Pd/FTO catalyst exhibited high catalytic activity towards 4-NP reduction with a rate constant of 1.776 min(-1) and turnover frequency (TOF) value of 29.1 hr(-1). The findings revealed that Pd/FTO also maintained its high stability for five consecutive runs in Suzuki reactions and 4-NP reductions. The catalyst showed excellent catalytic activities by using a small amount of Pd/FTO for the Suzuki coupling reaction and 4-NP reduction

Rapid ethical assessment on informed consent content and procedure in Hintalo-Wajirat, Northern Ethiopia: a qualitative study

Background Informed consent is a key component of bio-medical research involving human participants. However, obtaining informed consent is challenging in low literacy and resource limited settings. Rapid Ethical Assessment (REA) can be used to contextualize and simplify consent information within a given study community. The current study aimed to explore the effects of social, cultural, and religious factors during informed consent process on a proposed HPV-serotype prevalence study. Methodology A qualitative community-based REA was conducted in Adigudom and Mynebri Kebeles, Northern Ethiopia, from July to August 2013. Data were collected by a multi-disciplinary team using open ended questions concerning informed consent components in relation to the parent study. The team conducted one-to-one In-Depth Interviews (IDI) and Focus Group Discussions (FGDs) with key informants and community members to collect data based on the themes of the study. Tape recorded data were transcribed in Tigrigna and then translated into English. Data were categorized and thematically analyzed using open coding and content analysis based on pre-defined themes. Results The REA study revealed a number of socio-cultural issues relevant to the proposed study. Low community awareness about health research, participant rights and cervical cancer were documented. Giving a vaginal sample for testing was considered to be highly embarrassing, whereas giving a blood sample made participants worry that they might be given a result without the possibility of treatment. Verbal consent was preferred to written consent for the proposed study. Conclusion This rapid ethical assessment disclosed important socio-cultural issues which might act as barriers to informed decision making. The findings were important for contextual modification of the Information Sheet, and to guide the best consent process for the proposed study. Both are likely to have enabled participants to understand the informed consent better and consequently to comply with the study