ghanaopendata/ghanaian-research-english huggingface dataset:
Nonlinear Polarization Effects In A Birefringent Single Mode Optical Fiber

In this thesis, an investigation is conducted on the nonlinear polarization effects in a birefringent single mode optical fiber. The thesis begins with an introduction that gives current interests as well as a general review of polarization behavior in a birefringent, single mode fiber. The theory on propagation of light in single mode optical fibers is also introduced to serve ~ a basis for understanding the concepts of nonlinear polarization effects. Then Stokes parameters and the Stokes formalism are introduced and related to the traditional measures of light polarization such as ellipticity and azimuth. The use of Stokes parameters to analyze polarization effects as the beam propagates in a birefringent optical fiber forms the central theme of this thesis. The evolution equations for Stokes parameters when the optical fiber is considered linear are derived using the methods of Brown's Unified Formalism for Polarization Optics. Several Mueller matrices which characterize the polarization effects of birefringence and dichroism are obtained analytically. This provides a means to model the evolution of the Stokes parameters as function of fiber length and orientation angle. Graphical illustrations showing the output polarization change are presented in this thesis. Furthermore, general solutions to the Stokes parameters evolution equations when the optical fiber is considered nonlinear have been obtained analytically in terms of the Jacobian elliptic functions. Graphical illustration showing the nonlinear behavior of the output polarization are also presented. A fundamental and noteworthy aspect of the results presented in this thesis is that when the fiber is considered linear the output Stokes parameters are either periodic or constant with length or orientation angle depending on whether the fiber is assumed to have losses or not. When the solutions are periodic, the three Stokes parameters are observed to have the same periods. However, when the fiber response to propagation is considered nonlinear, the output Stokes parameters are generally doubly periodic, and the three Stokes parameters do not have the same periods. Some cases of aperiodicity are observed and presented. Another interesting and novel result presented in this thesis is that when an intense elliptically polarized beam propagating along a birefringent optical fiber undergoes a change in both its shape and orientation, the critical input intensity at which the light induced birefringence cancels the existing fiber birefringence will increase.

Source: UCC
Nonparametric Stepwise Procedure for Identification of Maximum Safe Dose (MSD)

In this article we consider identification of maximum safe dose (MSD) in a dose response study for distribution-free endpoints. Where the maximum safe dose is the highest dose level that does not exceed the median toxicity of the zero dose by a predetermined margin. A nonparametric confidence set-based approach was proposed, that is we incorporate Mann-Whitney method with the partitioning principle in a step-down fashion for safety evaluation. A comprehensive study of the familywise error rate for our new procedure was compared with the dose response (DR) procedure via a Monte Carlo simulations. An example from preclinical trial in genetic toxicology was used for illustrative purpose

Source: UCC
Normal Non-HDL Cholesterol, Low Total Cholesterol, and HDL Cholesterol Levels in Sickle Cell Disease Patients in the Steady State: A Case-Control Study of Tema Metropolis

Background. Abnormal lipid homeostasis in sickle cell disease (SCD) is characterized by defects in plasma and erythrocyte lipids and may increase the risk of cardiovascular disease. This study assessed the lipid profile and non-HDL cholesterol level of SCD patients. Methods. A hospital-based cross-sectional study was conducted in 50 SCD patients, in the steady state, aged 8–28 years, attending the SCD clinic, and 50 healthy volunteers between the ages of 8–38 years. Serum lipids were determined by enzymatic methods and non-HDL cholesterol calculated by this formula: non-HDL-C = TC-HDL-C. Results. Total cholesterol (TC) (𝑝 = 0.001) and high-density lipoprotein cholesterol (HDL-C) (𝑝 < 0.0001) were significantly decreased in cases compared to controls. The levels of non-HDL-C, low-density lipoprotein cholesterol (LDL-C), and triglyceride (TG) were similar among the participants. The levels of decrease in TC and HDL were associated with whether a patient was SCD-SS or SCD-SC. Systolic blood pressure and diastolic blood pressure were each significantly associated with increased VLDL [SBP, 𝑝 = 0.01, OR: 0.74 (CI: 0.6–0.93); DBP, 𝑝 = 0.023, OR: 1.45 (CI: 1.05–2.0)]. Conclusion. Dyslipidemia is common among participants in this study. It was more pronounced in the SCD-SS than in SCD-SC. This dyslipidemia was associated with high VLDL as well as increased SBP and DBP.

Source: UCC
Normative Values of Retinal Nerve Fibre Layer Thickness and Optic Nerve Head Parameters and Their Association with Visual Function in an African Population

Purpose. To determine normative values of retinal nerve fibre layer thickness (RNFL) and optic nerve head (ONH) parameters and their association with routine clinical tests such as refractive error (RE), stereoacuity (SA), and contrast sensitivity (CS) in an African population. Methods. In a cross-sectional observational study, 100 normal subjects aged 20 to 78 years were evaluated using the Cirrus HD-OCT 5000 and matched with 200 glaucoma patients. Results. Average (±SD) RNFL thickness for normal subjects was found to be 102.37 ± 7.45 (range, 82–119 microns) compared with 90.74 ± 14.50 found for glaucoma subjects. Females had higher average RNFL values (104.84 ± 6.90) compared with males (99.80 ± 7.18). Significant associations were calculated between quadrant RNFL thickness and SA, SE, and CS (all p < 0.05). +e mean cup to disc ratio (CDR) was 0.49 ± 0.12, and mean optic disc area (DA) was 2.08mm2 ± 0.40. Smaller DA was recorded for participants aged 60+ years (1.86 ± 0.25), followed by 40–59 age group (2.01 ± 0.41) and then 20–39 age group (2.19 ± 0.41). Significant associations were calculated between SA and ONH parameters, except rim area (all p < 0.01), and RE was significantly associated with DA and average CDR (all p < 0.05). Conclusion. RNFL thickness in healthy black Ghanaian population was significantly higher than that reported in other races. +e values and associations reported in this study can inform clinical decision on the normal variation in RNFL and optic disc parameters.

Source: UCC
Nosocomial infections are still a major concern in peri- urban polyclinics in Ghana

The study assessed potential sources of nosocomial infections as well as the knowledge of healthcare workers about these infections in a peri-urban polyclinic of Ghana. Swabs were taken in duplicates from beds in the wards, door knobs, sinks, nurses’ desks, taps handles, delivery beds, wound dressing rooms, and door and flashing handles of lavatories. After overnight incubation, the samples were serially diluted two times and the third diluent was used in culturing unto plate counting agar, MacConkey agar, blood agar and incubated at 35±2°C for 24 h. The plates were read for colonies and isolated colonies were identified. A simple random method was used to sample the respondents from the various departments in the Polyclinic. Structured questionnaires were administered to solicit their knowledge or understanding of possible causes of nosocomial infections and their perception of the efficacy of the cleaning processes employed in the facility as well as measures put in place to protect healthcare workers from these infections. Data collected showed that Bacillus spp. was the predominant bacterium isolated contributing 64.3% of the total isolate. Out of the 24 pathogenic organisms forming 35.7% of the total organisms isolated, Staphylococcus aureus (94.8%) formed the majority and Pseudomonas aeruginosa (5.2%) was the least isolated. There was no significant difference between the number of isolates recorded before cleaning and after cleaning (P > 0.05) with almost the same number and type of organisms isolated in both cases. Apart from the orderlies who demonstrated little knowledge on nosocomial infections, all the other healthcare workers exhibited adequate knowledge of nosocomial infections. The seemingly high percentage of pathogenic isolates from our study site indicates a high potential risk of nosocomial infections in peri-urban polyclinics.

Source: UCC
Nosocomial Infections are Still a Major Concern in Periurban Polyclinics in Ghana

The study assessed potential sources of nosocomial infections as well as the knowledge of healthcare workers about these infections in a peri-urban polyclinic of Ghana. Swabs were taken in duplicates from beds in the wards, door knobs, sinks, nurses’ desks, taps handles, delivery beds, wound dressing rooms, and door and flashing handles of lavatories. After overnight incubation, the samples were serially diluted two times and the third diluent was used in culturing unto plate counting agar, MacConkey agar, blood agar and incubated at 35±2°C for 24 h. The plates were read for colonies and isolated colonies were identified. A simple random method was used to sample the respondents from the various departments in the Polyclinic. Structured questionnaires were administered to solicit their knowledge or understanding of possible causes of nosocomial infections and their perception of the efficacy of the cleaning processes employed in the facility as well as measures put in place to protect healthcare workers from these infections. Data collected showed that Bacillus spp. was the predominant bacterium isolated contributing 64.3% of the total isolate. Out of the 24 pathogenic organisms forming 35.7% of the total organisms isolated, Staphylococcus aureus (94.8%) formed the majority and Pseudomonas aeruginosa (5.2%) was the least isolated. There was no significant difference between the number of isolates recorded before cleaning and after cleaning (P > 0.05) with almost the same number and type of organisms isolated in both cases. Apart from the orderlies who demonstrated little knowledge on nosocomial infections, all the other healthcare workers exhibited adequate knowledge of nosocomial infections. The seemingly high percentage of pathogenic isolates from our study site indicates a high potential risk of nosocomial infections in peri-urban polyclinics.

Source: UCC
Not Everyone Fits the Mold: Intratumor and Intertumor Heterogeneity and Innovative Cancer Drug Design and Development

Disruptive innovations in medicine are game-changing in nature and bring about radical shifts in the way we un- derstand human diseases, their treatment, and/or prevention. Yet, disruptive innovations in cancer drug design and development are still limited. Therapies that cure all cancer patients are in short supply or do not exist at all. Chief among the causes of this predicament is drug resistance, a mechanism that is much more dynamic than previously understood. Drug resistance has limited the initial success experienced with biomarker-guided targeted therapies as well. A major contributor to drug resistance is intratumor heterogeneity. For example, within solid tumors, there are distinct subclones of cancer cells, presenting profound complexity to cancer treatment. Well-known con- tributors to intratumor heterogeneity are genomic instability, the microenvironment, cellular genotype, cell plasticity, and stochastic processes. This expert review explains that for oncology drug design and development to be more innovative, we need to take into account intratumor heterogeneity. Initially thought to be the preserve of cancer cells, recent evidence points to the highly heterogeneous nature and diverse locations of stromal cells, such as cancer-associated fibroblasts (CAFs) and cancer-associated macrophages (CAMs). Distinct subpopulations of CAFs and CAMs are now known to be located immediately adjacent and distant from cancer cells, with different subpopulations exerting different effects on cancer cells. Disruptive innovation and precision medicine in clinical oncology do not have to be a distant reality, but can potentially be achieved by targeting these spatially separated and exclusive cancer cell subclones and CAF subtypes. Finally, we emphasize that disruptive innovations in drug discovery and development will likely come from drugs whose effect is not necessarily tumor shrinkage.

Source: UCC
Not just numbers: beyond counting caesarean deliveries to understanding their determinants in Ghana using a population based cross-sectional study

The increasing rate of caesarean deliveries (CD) has become a serious concern for public health experts globally. Despite this health concern, research on factors associated CD in many low- and -middle countries like Ghana is sparse. This study, therefore, assessed the prevalence and determinants of CD among child-bearing women aged 15–49 in Ghana. The study used data from the 2014 Ghana Demographic and Health Survey. The analysis was limited to mothers (n = 2742) aged 15–49 , who had given birth in health facilities 5 years preceding the survey. Association between CD and its determinants was assessed by calculating adjusted odds ratios (AOR) with their respective 95% confidence intervals using a binary logistic regression. The percentage of mothers who delivered their babies through caesarean section (CS) was 18.5%. Using multivariable logistic regression, the results showed that women aged 45–49 (AOR = 10.5; 95% CI: 3.0–37.4), and women from a household that are headed by a female (AOR = 1.3; 95% CI = 1.1–1.7) had higher odds to deliver through CS. Women from the Upper East (AOR =0.4; 95% CI = 0.2–0.7) and Upper West (AOR = 0.4; 95% CI = 0.2–0.8) regions had lower odds to deliver their children through CS. Women with parity 4 or more (AOR = 0.3; 95% CI = 0.2–0.5) had lower odds of CD compared to those with parity 1. Women with female babies had lower odds (AOR = 0.8; CI = 0.7–0.9) of delivering them through CS compared to those with male children. The percentage of women delivering babies through the CS in Ghana is high. The high rates of CD noted do not essentially indicate good quality care or services. Hence, health facilities offering this medical protocol need to adopt comprehensive and strict measures to ensure detailed medical justifications by doctors for performing these caesarean surgeries.

Source: UCC
A Novel Antibody Targeting CD24 and Hepatocellular Carcinoma in Vivo by Near-Infrared Fluorescence Imaging

Liver cancer is one of the most common malignant cancers worldwide. The poor response of liver cancer to chemotherapy has whipped up the interest in targeted therapy with monoclonal antibodies because of its potential efficiency. One promising target is cluster of differentiation 24 (CD24), which is known to beover-expressed on hepatocellular carcinoma (HCC), providing prospect for HCC targeted diagnosis and therapy. In this study we developed a novel CD24 targeted monoclonal antibody G7mAb based on hybridoma technology and then generated a single-chain antibodyfragment (scFv) G7S. Firstly, ELISA, western blot, and flow cytometry assays demonstrated specific binding of CD24 by G7mAb and G7S. Further, G7mAb was demonstrated to have similar binding capacity as ML5 (a commercial Anti-CD24 Mouse Antibody) inimmunohistochemical assay. Further more, a near-infrared fluorescent dye multiplex probe amplification (MPA) was conjugated to G7mAb and G7S to form G7mAb-MPA and G7S-MPA. The nearinfrared fluorescence imaging revealed that G7mAb and G7S aggregate in CD24 + Huh7 hepatocellular carcinoma xenograft tissuevia specific binding to CD24 in vivo. In conclussion, G7mAb and G7S were tumor targeted therapeutic and diagnostic potentials in vitro and in vivo as anticipated.

Source: UCC
Novel bio-friendly and non-toxic thiocarbohydrate stabilizers of gold nanoparticles

Several bio-friendly carbohydrate disulfides and thiocarbohydrates have been synthesized via the reaction of D-(+)-gluconic acid δ-lactone with aminoalkylthiols, leading to n gluconamidoalkyldisulfides {di-(2-gluconamidoethyl)disulfide (L1), di(3-gluconamidopropyl)-disulfide (L2), di(4-gluconamidobutyl) disulfide (L3) and (2-gluconamidoethyl)thiol (L4)}. Acetylation of hydroxy groups in L1-L3 and subsequent reduction produced the following disulfides and thiols: acetylated di(2-gluconamidoethyl)disulfide (L5), acetylated di(3- gluconamidopropyl)disulfide (L6), acetylated di(4-gluconamidobutyl)disulfide (L7), acetylated di(2-gluconamidoethyl)thiol (L8), acetylated di(3-gluconamidopropyl)thiol (L9) and acetylated di(4-gluconamidobutyl)thiol (L10). Compounds L1-L10 were characterized by combination of NMR and infrared spectroscopy, microanalysis, mass spectrometry and in a selected case X-ray crystallographic data. These thiocarbohydrate compounds were used to stabilize gold nanoparticles to gold glyconanoparticles (AuNPs) of sizes in the range of ca. 2-9 nm. The thiocrabohydrates are non-toxic toward both cancer and normal cell lines and have IC50 values generally ≥ 200 µΜ

Source: UCC
A Novel Bispecific Diabody Targeting both Vascular Endothelial Growth Factor Receptor 2 and Epidermal Growth Factor Receptor for Enhanced Antitumor Activity

Epidermal growth factor receptor (EGFR) and vascular endothelial growth factor receptor 2 (VEGFR2) are receptor tyrosine kinases known to play critical roles in the development and progression of tumors. Based on the cross-talk between EGFR and VEGFR2 signal pathways, we designed and produced a bispecific diabody (bDAb) targeting both EGFR and VEGFR2 simultaneously. The bispecific molecule (EK-02) demonstrated that it could bind to HUVEC (VEGFR2 high-expressing) and A431 (EGFR overexpressing) cells. Additionally, similar to the parental antibodies, it was able to inhibit proliferation and migration, and induced apoptosis in these cells (HUVECs and A431), demonstrating that it had retained the functional properties of its parental antibodies. Furthermore, the efficacy of EK-02 was eval- uated using the human colon adenocarcinoma cell line HT29 (VEGFR2 and EGFR coex- pressing). In vitro assay showed that EK-02 could bind to HT29 cells, restrain cell growth and migration, and induce apoptosis with enhanced efficacy compared to both parental anti- bodies. Further, it inhibited the neovascularization and tumor formation on an HT29 cell bearing chicken chorioallantoic membrane (CAM) tumor model in vivo. In conclusion, these data suggest that the novel bDAb (EK-02) has antiangiogenesis and antitumor capacity both in vitro and in vivo, and can possibly be used as cotargeted therapy for the treatment of C 2016 American Institute of Chemical Engi- EGFR and VEGFR2 overexpressing tumors. V neers Biotechnol. Prog., 32:294–302, 2016 Keywords: epidermal growth factor receptor (EGFR), vascular endothelial growth factor receptor 2 (VEGFR2), bispecific diabody (bDAb), single-chain fragment (scFv), antiangio- genesis, antitumor

Source: UCC
A Novel Fusion Antibody Exhibits Antiangiogenic Activity and Stimulates NK Cell-mediated Immune Surveillance Through Fused NKG2D Ligand

A single-chain variable fragment (scFv) targeting vas- cular endothelial growth factor receptor 2 was previously generated from a phage display library in our laboratory. However, it has shortened half-life and lacks Fc fragment for eﬀector cell recog- nition. To address these challenges, a ligand of NK-cell receptor NKG2D was fused to the scFv and created a fusion protein scFv- major histocompatibility complex class I-related chain A (MICA), which is expected to recognize tumor cells through the scFv moiety and stimulate NK cells through the MICA. The fusion protein demonstrated speciﬁc binding to both vascular endothelial growth factor receptor 2 and NKG2D in protein-based and cell-based assays. In addition, it demonstrated antiangiogenic activities including restraining the proliferation, migration, transwell inva- sion, and tube formation of human umbilical vein endothelial cells. Furthermore, the fusion protein exhibited signiﬁcant cytotoxicity on K562, MDA-MB-435, and B16F10 cells and triggered NK92 cell-mediated cytotoxicity on MDA-MB-435 cells by stimulating the release of signiﬁcant cytokines. The fusion protein targeting strategy, therefore, provides a means to engage lymphocyte eﬀector cells against tumor speciﬁc antigen overexpressing tumor cells.

Source: UCC
A novel hybrid discrete cosine transformation and visual cryptographic technique for securing digital images

Security of digital images in today’s cyber is a major concern. Transmission of compressed and uncompressed multimedia data is necessary for communication between different devices. Devices of different screen features and resolution need very efficient and fast compression techniques in order to maintain visual features of transmitted media. Robustness is of a key consideration and importance in image compression techniques. Full recovery of images after compression is a challenge for image compression algorithms. It is practically closely impossible for most encrypted-compressed-images or compressed-encrypted images to be efficiently and fully reconstructed. In this paper we proposed a robust, efficient and fully recoverable encrypted-compressed image based on hybrid discrete cosine transformation and visual cryptographic technique for securing digital images. We first encrypted the image without pixel loss and then compressed the image which resulted into pixel loss during the compression phase. We decrypted the compressed image by obtaining perfect visuals but losses in pixel values. The analysis of the process proved to be an efficient way of encrypting images and compressing them for other channels with less data capacity without the worry of visual loss as well as ensuring security of the data during transmission. The programming and implementation was done using MATLAB

Source: UCC
A novel inhibitor of human telomerase derived from 10h-indolo[3,2-b]quinoline

The bis-dimethylaminoethyl derivative of quindoline (10H-indolo[3,2-b]quinoline), an alkaloid from the West African shrub Cryptolepis sanguinolenta, has been synthesised. This has been shown to have modest cytotoxicity, as well as inhibitory activity against the telomerase enzyme. It is hypothesized that the latter activity is due to stabilization of an intermediate guaninquadruplex complex, in accordance with computer modelling

Source: UCC
A novel method of three-dimensional hetero spectral correlation analysis for the fingerprint identification of humic acid functional groups for hexavalent chromium retention†

Two-dimensional hetero-spectral correlation analysis has been widely used for the interpretation of spectral changes of humic substances involved in various environmental processes. However, when three different types of spectroscopies are utilized, only a pairwise correlation can be achieved. In order to overcome this problem, a novel method of three-dimensional hetero-spectral correlation analysis with scaling technique was developed in this study, which can further establish a direct correlation between three different types of spectroscopies, including FTIR, 13 C CP/MAS NMR, and XPS. The proposed method was applied to the fingerprint identification of undissolved humic acid functional groups for Cr(VI) retention, which is one of the most important points for understanding the migration and transformation of Cr(VI) in a subsurface environment. The results indicated that mainly free and dissociated carboxylic groups, phenolic groups, and polysaccharide participated in the reaction with Cr(VI), and these functional groups were mainly located at aromatic domains. Besides, the variations of functional groups were related to the reduction of Cr(VI), and the reduced Cr(III) mainly bound to aromatic domains. The successful application of the proposed method demonstrated that it can serve as a promising tool for further investigations concerning more complicated environmental processes and even other scientific fields by supplying more detailed, reliable and visualized spectral information

Source: UCC