Economic Efficiency of Sharecropping in Drylands: A Case Study of Gum Arabic Production in Kordofan Gum Belt, Sudan

The enigma of sharecropping as an economic institution of resource allocation has a long history and always been a fruitful source of controversy in economic literature. The Marshallian economists generally condemned sharecropping as an inefficient institution in that it did not provide incentives to the sharecroppers, because producers had to share the output with the landlords, while the Cheungian economists claimed sharecropping to be as efficient as any other tenure system. This study examines the empirical validity of these two approaches, using evidence from the Kordofan gum arabic orchards of Sudan. This study was planned mainly to examine the differences in input and output intensities among the mixed and pure sharecroppers of gum arabic orchards. Mixed sharecroppers are gum farmers who rent-in land besides cultivating own land. Pure sharecroppers are gum farmers who rent-in land with no land of their own. We examined these differences by modeling three comparison cases. Case (A) compares input and output differences on owned versus sharecropped gum orchards of mixed sharecroppers. Case (B) compares input and output differences on the owned orchards of mixed sharecroppers with the gum orchards of pure sharecroppers. Case (C) compares input and output differences on the shared gum orchards of mixed sharecroppers with the gum orchards of pure sharecroppers. The significance of these differences in input and output intensities was measured by employing two test procedures. An F-test based on Hotelling's T2 statistic was employed to measure the significance of differences in input and output intensities of comparable but different cases. The second test, which is based on Shaban's methodology, measures the impact of tenancy on input and output intensities by isolating the pure tenancy effect from the total variation in input and output intensities. Shaban's methodology was modified to incorporate five new variables: gum orchard size, gum trees capital services flow, gum trees tapping intensity, rainfall and its fluctuation, and soil type, in the model. The findings of the study reveal that total differences in inputs and output intensities across the tenure systems can be explained by differences in gum orchard size, gum trees capital services flow, gum trees tapping intensity, rainfall and its fluctuation, soil type and the tenancy effect. The tenancy effect and gum orchard specific characteristics (in particular differences in gum orchard size, gum trees capital services flow, rainfall and its fluctuation, and tapping intensity) are the most significant factors in determining inputs and output intensities. The results of this study also indicate that the impact of tenancy is stronger and more sizeable for those inputs that are not shared by the gum orchard owner. Mixed sharecroppers apply more family labour in their owned-operated gum orchards than in the shared-operated orchards they tap. Among the shared inputs, differences in input intensity are sizeable and significant for other inputs variable. There are similar results in case (B) (comparing owned-operated gum orchards of mixed sharecroppers and pure sharecroppers), though differences in inputs and output intensities are relatively smaller, a result consistent with Bell's findings. Our case (C) comparison between mixed sharecroppers and pure sharecroppers is fully corroborating Bell's findings. A sharecropper-owned resources such as family labour is used more intensively in pure sharecropped gum orchards in the case (C) comparison. Input intensity of other inputs is mainly determined by input share rules applicable to them. Mixed as well as pure sharecroppers' input intensity increases when their gum orchard owners share these inputs. Our empirical results, moreover, contain some implications for the theoretical controversy . between the traditional and the Cheungian views of land tenure arrangements. Our results, which confirm and extend the earlier views of Bell and Shaban, support the traditional view of the matter; in some relative sense sharecropping arrangements are less efficient than production on owned gum orchards

New applications of Imidazotetrazinone prodrugs. Synthesis and mechanistic investigation of novel imidazotetrazinones as prodrugs of aziridines and as traceless carriers for drug delivery to the central nervous system.

New imidazotetrazinones have been synthesised that possess features in their structures to release aziridinium ions upon ring opening. Unstable 2-aminoethylisocyanates were required in this preparation, which were synthesized with BOC-protection of the amino group to counteract the reactivity of the amine towards the isocyanate group in the case of aliphatic amines; in contrast, anilinoethylisocyanates were synthesized unprotected. Substituents with a range of electron-withdrawing and electron-releasing properties were introduced at the p-position of the aniline ring. A 13C-labelled study confirmed the release of the aziridinium ion by these imidazotetrazinones in neutral pH buffer solution. Furthermore the kinetics of the hydrolysis in neutral aqueous solution of some these new tetrazines were similar to temozolomide, in addition to useful acid stability. Other imidazotetrazinones were synthesised for the purpose of releasing alcohols and phenols. Their synthesis was performed with a one-carbon linker between the imidazotetrazinone 3-position and the alcohols or phenols to be released. The release of alcohol and phenol through the hydrolysis of the intermediate diazonium ions to the unstable hemiacetals that decomposed to the alcohol and phenol was confirmed by 1H NMR. The kinetics of the hydrolysis of these tetrazines in neutral aqueous solution showed a faster reaction rate compared with temozolomide (t1/2 = 0.53 and 0.36 h compared with temozolomide 1.4 h).Full text was made available at the end of the embargo period, 1st Feb 2016

Synthesis and Quantitative Structure–Activity Relationship of Imidazotetrazine Prodrugs with Activity Independent of O6-Methylguanine-DNA-methyltransferase, DNA Mismatch Repair and p53.

The antitumor prodrug Temozolomide is compromised by its dependence for activity on DNA mismatch repair (MMR) and the repair of the chemosensitive DNA lesion, O6-methylguanine (O6-MeG), by O6-methylguanine-DNA-methyltransferase (EC 2.1.1.63, MGMT). Tumor response is also dependent on wild-type p53. Novel 3-(2-anilinoethyl)-substituted imidazotetrazines are reported that have activity independent of MGMT, MMR and p53. This is achieved through a switch of mechanism so that bioactivity derives from imidazotetrazine-generated arylaziridinium ions that principally modify guanine-N7 sites on DNA. Mono- and bi-functional analogs are reported and a quantitative structure-activity relationship (QSAR) study identified the p-tolyl-substituted bi-functional congener as optimized for potency, MGMT-independence and MMR-independence. NCI60 data show the tumor cell response is distinct from other imidazotetrazines and DNA-guanine-N7 active agents such as nitrogen mustards and cisplatin. The new imidazotetrazine compounds are promising agents for further development and their improved in vitro activity validates the principles on which they were designed

Variability in mortality following caesarean delivery, appendectomy, and groin hernia repair in low-income and middle-income countries: a systematic review and analysis of published data

Background Surgical interventions occur at lower rates in resource-poor settings, and complication and death rates following surgery are probably substantial but have not been well quantifi ed. A deeper understanding of outcomes is a crucial step to ensure that high quality accompanies increased global access to surgical care. We aimed to assess surgical mortality following three common surgical procedures—caesarean delivery, appendectomy, and groin (inguinal and femoral) hernia repair—to quantify the potential risks of expanding access without simultaneously addressing issues of quality and safety. Methods We collected demographic, health, and economic data for 113 countries classifi ed as low income or lower-middle income by the World Bank in 2005. We did a systematic review of Ovid, MEDLINE, PubMed, and Scopus from Jan 1, 2000, to Jan 15, 2015, to identify studies in these countries reporting all-cause mortality following the three commonly undertaken operations. Reports from governmental and other agencies were also identifi ed and included. We modelled surgical mortality rates for countries without reported data using a two-step multiple imputation method. We fi rst used a fully conditional specifi cation (FCS) multiple imputation method to establish complete datasets for all missing variables that we considered potentially predictive of surgical mortality. We then used regression-based predictive mean matching imputation methods, specifi ed within the multiple imputation FCS method, for selected predictors for each operation using the completed dataset to predict mortality rates along with confi dence intervals for countries without reported mortality data. To account for variability in data availability, we aggregated results by subregion and estimated surgical mortality rates. Findings From an initial 1302 articles and reports identifi ed, 247 full-text articles met our inclusion criteria, and 124 provided data for surgical mortality for at least one of the three selected operations. We identifi ed 42 countries with mortality data for at least one of the three procedures. Median reported mortality was 7·9 per 1000 operations for caesarean delivery (IQR 2·8–19·9), 2·2 per 1000 operations for appendectomy (0·0–17·2), and 4·9 per 1000 operations for groin hernia (0·0–11·7). Perioperative mortality estimates by subregion ranged from 2·8 (South Asia) to 50·2 (East Asia) per 1000 caesarean deliveries, 2·4 (South Asia) to 54·0 (Central sub-Saharan Africa) per 1000 appendectomies, and 0·3 (Andean Latin America) to 25·5 (Southern sub-Saharan Africa) per 1000 hernia repairs. Interpretation All-cause postoperative mortality rates are exceedingly variable within resource-constrained environments. Eff orts to expand surgical access and provision of services must include a strong commitment to improve the safety and quality of care

Unlocking the potential of approved drugs for the allosteric inhibition of tropomyosin-receptor kinase A using molecular docking and molecular dynamics studies

Tropomyosin-receptor kinase A (TrkA) is the primary isoform among the tropomyosin-receptor kinases that have been associated with human cancer development, contributing to approximately 7.4% of all cancer cases. TrkA represents an attractive target for cancer treatment; however, currently available TrkA inhibitors face limitations in terms of resistance development and potential toxicity. Hence, the objective of this study was to identify new allosteric-approved inhibitors of TrkA that can overcome these challenges and be employed in cancer therapy. To achieve this goal, a screening of 9,923 drugs from the ChEMBL database was conducted to assess their repurposing potential using molecular docking. The top 49 drug candidates, exhibiting the highest docking scores (−11.569 to −7.962 kcal/mol), underwent MM-GBSA calculations to evaluate their binding energies. Delanzomib and tibalosin, the top two drugs with docking scores of −10.643 and −10.184 kcal/mol, respectively, along with MM-GBSA dG bind values of −67.96 and −50.54 kcal/mol, were subjected to 200 ns molecular dynamic simulations, confirming their stable interactions with TrkA. Based on these findings, we recommend further experimental evaluation of delanzomib and tibalosin to determine their potential as allosteric inhibitors of TrkA. These drugs have the potential to provide more effective and less toxic therapeutic alternatives. The approach employed in this study, which involves repurposing drugs through molecular docking and molecular dynamics, serves as a valuable tool for identifying novel drug candidates with distinct therapeutic uses. This methodology can contribute to reducing the attrition rate and expediting the process of drug discovery

Design ; implementation of mobile communication networks based on the Virtual Bus concept

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Microwave-assisted single-step synthesis of acid hydrazides from corresponding acids utilizing newly designed apparatus

Acid hydrazides are essential intermediates in organic synthesis. They conventionally require a two-step synthetic pathway; esterification and hydrazine hydrate treatment; to obtain the hydrazide. The microwave-assisted synthetic methodology was utilized as a greener and straightforward single-step approach for their synthesis in highly encouraging yields. Thus, the aim of the present work was to synthesize acid hydrazides of Diclofenac, Indomethacin, Ibuprofen, and Mefenamic acid using microwave radiation with the aid of a newly designed fit-in ice condenser. Esters of the selected compounds were firstly synthesized, and acid hydrazides were then synthesized utilizing both the conventional and the proposed microwave-assisted single-step methods. The developed technique was successfully yielded 86.7%, 40.9%, and 65.5% acid hydrazides of Diclofenac, Indomethacin, and Mefenamic acid in just 3 min., 10 min. and 3 min., respectively. In comparison to the conventional method, the developed method was simpler with a very short reaction time and quantified yields. The structures of the synthesized acid hydrazides were also confirmed using FT-IR and 1H-NMR. The proposed method with the modified fit-in ice condenser proved to be efficient, cost-effective, and time-saving in the synthesis of acid hydrazides understudy in a single step

External strangulated hernia in Khartoum, Sudan

No Abstract. East African Medical Journal Vol. 84 (6) 2007: pp. 379-38

Microwave-assisted Single-step Synthesis of Acid Hydrazides From Corresponding Acids Utilizing Newly Designed Apparatus

Acid hydrazides are essential intermediates in organic synthesis. They conventionally require a two-step synthetic pathway; esterification and hydrazine hydrate treatment; to obtain the hydrazide. The microwave-assisted synthetic methodology was utilized as a greener and straightforward single-step approach for their synthesis in highly encouraging yields. Thus, the aim of the present work was to synthesize acid hydrazides of Diclofenac, Indomethacin, Ibuprofen, and Mefenamic acid using microwave radiation with the aid of a newly designed fit-in ice condenser. Esters of the selected compounds were firstly synthesized, and acid hydrazides were then synthesized utilizing both the conventional and the proposed microwave-assisted single-step methods. The developed technique was successfully yielded 86.7%, 40.9%, and 65.5% acid hydrazides of Diclofenac, Indomethacin, and Mefenamic acid in just 3 min., 10 min. and 3 min., respectively. In comparison to the conventional method, the developed method was simpler with a very short reaction time and quantified yields. The structures of the synthesized acid hydrazides were also confirmed using FT-IR and 1H-NMR. The proposed method with the modified fit-in ice condenser proved to be efficient, cost-effective, and time-saving in the synthesis of acid hydrazides understudy in a single step