Using CERES-maize and ENSO as decision support tools to evaluate climate-sensitive farm management practices for maize production in the northern regions of Ghana

Open Access JournalMaize (Zea mays) has traditionally been a major cereal staple in southern Ghana. Through breeding and other crop improvement efforts, the zone of cultivation of maize has now extended to the northern regions of Ghana which, hitherto, were the home to sorghum and millet as the major cereals. Maize yield in the northern Ghana is hampered by three major biophysical constraints, namely, poor soil fertility, low soil water storage capacity and climate variability. In this study we used the DSSAT crop model to assess integrated water and soil management strategies that combined the pre-season El-Niño-Southern Oscillation (ENSO)-based weather forecasting in selecting optimal planting time, at four locations in the northern regions of Ghana. It could be shown that the optimum planting date for a given year was predictable based on February-to-April (FMA) Sea Surface Temperature (SST) anomaly for the locations with R2 ranging from 0.52 to 0.71. For three out of four locations, the ENSO-predicted optimum planting dates resulted in significantly higher maize yields than the conventional farmer selected planting dates. In Wa for instance, early optimum planting dates were associated with La Nina and El Niño (Julian Days 130-150; early May to late May) whereas late planting (mid June to early July) was associated with the Neutral ENSO phase. It was also observed that the addition of manure and fertilizer improved soil water and nitrogen use efficiency, respectively, and minimized yield variability, especially when combined with weather forecast. The use of ENSO-based targeted planting date choice together with modest fertilizer and manure application has the potential to improve maize yields and also ensure sustainable maize production in parts of northern Ghana

Validity of bioeffect dose response models for normal tissue early and late complications of the skin

SummaryBackgroundThe bioeffect of a physical dose depends on the nature of the tissue, fractionation scheme, dose rate and treatment time. Certainly, experienced radiotherapists are convinced of the existence of patient-to-patient variability in normal tissue response to radiotherapy for malignant tumours. The absorbed dose needs to be translated into a bioeffect dose, which takes into account treatment variables and the radiobiological characteristics of the relevant tissue. Various bioeffect models such as NSD, CRE, TDF and BED have been proposed to predict the biological effect of radiotherapy treatments.AimThis study was aimed at deriving tolerance bioeffect dose values for normal tissue complication rate.Materials/MethodsCompiled clinical data of time dose fractionation schedules and incidence of erythema, desquamation and telangiectasia were used for the present analysis.ResultsFor erythema and desquamation the radiation dose varied from 23.9 to 55.1Gy in 04 to 50 fractions (dose per fraction 1.1 to 7.3Gy) in 11 to 40 days. For telangiectasia (score ≥1 at 3 years) the radiation dose varied from 25.8 to 55.1Gy in 04 to 50 fractions (dose per fraction 1.1 to 7.3Gy) in 11 to 40 days. For telangiectasia (score ≥2 at 5 years) the radiation dose varied from 25.8 to 63.0Gy in 04 to 50 fractions (dose per fraction 1.1 to 7.3Gy) in 11 to 68 days. For telangiectasia (score ≥1, ≥2, ≥3, ≥4 at 10 years) the radiation dose varied from 25.8 to 63.0Gy in 04 to 35 fractions (dose per fraction 1.7 to 7.3Gy) in 22 to 68 days. TDF and LQF values for erythema, desquamation and telangiectasia were evaluated with α/β values of 7.5Gy, 11.2Gy and 2.8Gy respectively. TDF and LQF had a statistically significant correlation with probability of erythema, desquamation and telangiectasia (p<0.001).ConclusionsTDF and LQF values should be limited to 60 and 86Gy in order to limit the probability of telangiectasia

Gravity and Geometric Phases

The behavior of a quantum test particle satisfying the Klein-Gordon equation in a certain class of 4 dimensional stationary space-times is examined. In a space-time of a spinning cosmic string, the wave function of a particle in a box is shown to acquire a geometric phase when the box is transported around a closed path surrounding the string. When interpreted as an Aharonov-Anandan geometric phase, the effect is shown to be related to the Aharonov-Bohm effect.Comment: 11 pages, latex fil

Validity of bioeffect dose response models for normal tissue early and late complications of the skin

BackgroundThe bioeffect of a physical dose depends on the nature of the tissue, fractionation scheme, dose rate and treatment time. Certainly, experienced radiotherapists are convinced of the existence of patient-to-patient variability in normal tissue response to radiotherapy for malignant tumours. The absorbed dose needs to be translated into a bioeffect dose, which takes into account treatment variables and the radiobiological characteristics of the relevant tissue. Various bioeffect models such as NSD, CRE, TDF and BED have been proposed to predict the biological effect of radiotherapy treatments.AimThis study was aimed at deriving tolerance bioeffect dose values for normal tissue complication rate.Materials/MethodsCompiled clinical data of time dose fractionation schedules and incidence of erythema, desquamation and telangiectasia were used for the present analysis.ResultsFor erythema and desquamation the radiation dose varied from 23.9 to 55.1Gy in 04 to 50 fractions (dose per fraction 1.1 to 7.3Gy) in 11 to 40 days. For telangiectasia (score ≥1 at 3 years) the radiation dose varied from 25.8 to 55.1Gy in 04 to 50 fractions (dose per fraction 1.1 to 7.3Gy) in 11 to 40 days. For telangiectasia (score ≥2 at 5 years) the radiation dose varied from 25.8 to 63.0Gy in 04 to 50 fractions (dose per fraction 1.1 to 7.3Gy) in 11 to 68 days. For telangiectasia (score ≥1, ≥2, ≥3, ≥4 at 10 years) the radiation dose varied from 25.8 to 63.0Gy in 04 to 35 fractions (dose per fraction 1.7 to 7.3Gy) in 22 to 68 days. TDF and LQF values for erythema, desquamation and telangiectasia were evaluated with α/β values of 7.5Gy, 11.2Gy and 2.8Gy respectively. TDF and LQF had a statistically significant correlation with probability of erythema, desquamation and telangiectasia (

Evaluating maize yield variability and gaps in two agroecologies in northern Ghana using a crop simulation model

Article purchased; Published online: 19 Oct 2017The yield gap and variability in maize under smallholder systems in two agroecologies in northern Ghana were evaluated using a decision support system for agrotechnology transfer (DSSAT). The model was used to assess (1) the potential yield of maize (YPOT), (2) water-limited exploitable maize yield (YWEX), (3) nitrogen-limited yield (YNI), (4) farmer practice maize yield (YCFP) and (5) proposed enhanced nutrient use yield (enhanced farmer practice; YEFP). Effect of supplementary irrigation was also assessed on YCFP and YEFP conditions. Yield gaps were determined as the difference between YPOT and YCFP or YEFP on the one hand, and between YWEX and YCFP or YEFP on the other hand. The yield gap based on potential yield ranged from 59% to 75% under CFP and narrowed to between 29% and 59% under EFP. With water-limited exploitable yields, the yield gap ranged from 53% to 65% under CFP, reducing to between 22% and 42% under EFP. The use of supplementary irrigation further reduced the yield gap. Improved fertiliser use and supplementary irrigation have the potential to increase yield and hence reduce the yield gap if effective policies and institutional structures are in place to provide farmers with credit facilities and farm inputs

Preparation and Characterization of Metformin Hydrochloride — Compritol 888 ATO Solid Dispersion

Metformin hydrochloride (MET) sustained-release solid dispersions (SD) were prepared by the solvent evaporation and closed melt method, using compritol 888 ATO as the polymer with five different drug-carrier ratios. Characterization of solid dispersion was carried out by Fourier Transform Infrared (FTIR) spectroscopy, ultraviolet (UV) spectroscopy, Differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD). The FTIR and UV studies suggested that no bond formation had occurred between the polymer and the drug. DSC and XPRD results ruled out any interaction or complex formation between the drug and the polymer. The formulated SD had acceptable physicochemical characters and SD with a 1 : 4 drug : Polymer ratio, which released the drug over an extended period of eight-to-ten hours. The data obtained from the in vitro release studies were fitted with various kinetic models and were found to follow the Korsmeyer-Peppas equation. The prepared SD showed good stability over the studied time period. The solvent evaporation method was found to be more helpful than the closed melt method, giving the sustained release action. The SD with a 1 : 4 ratio of drug to polymer, by the solvent evaporation method, was selected as the most effective candidate for the subsequent development of a well-timed, sustained-release dosage form of the drug

A monovalent chimpanzee adenovirus Ebola vaccine boosted with MVA

BACKGROUND The West African outbreak of Ebola virus disease that peaked in 2014 has caused more than 11,000 deaths. The development of an effective Ebola vaccine is a priority for control of a future outbreak. METHODS In this phase 1 study, we administered a single dose of the chimpanzee adenovirus 3 (ChAd3) vaccine encoding the surface glycoprotein of Zaire ebolavirus (ZEBOV) to 60 healthy adult volunteers in Oxford, United Kingdom. The vaccine was administered in three dose levels — 1×1010 viral particles, 2.5×1010 viral particles, and 5×1010 viral particles — with 20 participants in each group. We then assessed the effect of adding a booster dose of a modified vaccinia Ankara (MVA) strain, encoding the same Ebola virus glyco- protein, in 30 of the 60 participants and evaluated a reduced prime–boost interval in another 16 participants. We also compared antibody responses to inactivated whole Ebola virus virions and neutralizing antibody activity with those observed in phase 1 studies of a recombinant vesicular stomatitis virus–based vaccine expressing a ZEBOV glycoprotein (rVSV-ZEBOV) to determine relative potency and assess durability. RESULTS No safety concerns were identified at any of the dose levels studied. Four weeks after immunization with the ChAd3 vaccine, ZEBOV-specific antibody responses were similar to those induced by rVSV-ZEBOV vaccination, with a geometric mean titer of 752 and 921, respectively. ZEBOV neutralization activity was also similar with the two vaccines (geo- metric mean titer, 14.9 and 22.2, respectively). Boosting with the MVA vector increased virus-specific antibodies by a factor of 12 (geometric mean titer, 9007) and increased glycoprotein-specific CD8+ T cells by a factor of 5. Significant increases in neutralizing antibodies were seen after boosting in all 30 participants (geometric mean titer, 139; P<0.001). Virus-specific antibody responses in participants primed with ChAd3 remained positive 6 months after vaccination (geometric mean titer, 758) but were significantly higher in those who had received the MVA booster (geometric mean titer, 1750; P<0.001). CONCLUSIONS The ChAd3 vaccine boosted with MVA elicited B-cell and T-cell immune responses to ZEBOV that were superior to those induced by the ChAd3 vaccine alone. (Funded by the Wellcome Trust and others; ClinicalTrials.gov number, NCT02240875.