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Coexistence of Superconductivity and Ferromagnetism in Superconducting HoMo6S8  [PDF]
Tadesse Desta, Gebregziabher Kahsay
World Journal of Condensed Matter Physics (WJCMP) , 2015, DOI: 10.4236/wjcmp.2015.51004
Abstract: This work focuses on the theoretical investigation of the coexistence of superconductivity and ferromagnetism in the superconducting HoMo6S8. By developing a model Hamiltonian for the system and using the Green’s function formalism and equation of motion method, we have obtained expressions for superconducting transition temperature (Tc), magnetic order temperature (Tm), superconductivity order parameter (D) and magnetic order parameter (η). By employing the experimental and theoretical values of the parameters in the obtained expressions, phase diagrams of energy gap parameter versus transition temperature, superconducting transition temperature versus magnetic order parameter and magnetic order temperature versus magnetic order parameter are plotted separately. By combining the phase diagrams of superconducting transition temperature versus magnetic order parameter and magnetic order temperature versus magnetic order parameter, we have demonstrated the possible coexistence of superconductivity and ferromagnetism in superconducting HoMo6S8.<
Study of Upper Critical Magnetic Field of Superconducting HoMo6Se8  [PDF]
Tadesse Desta, Pooran Singh, Gebregziabher Kahsay
World Journal of Condensed Matter Physics (WJCMP) , 2015, DOI: 10.4236/wjcmp.2015.53013
Abstract: This work focuses on the study of mathematical aspects of upper critical magnetic field of superconducting HoMo6Se8. At zero external magnetic field, HoMo6Se8 was found to undergo a transition from the normal state to the superconducting state at 5.6 K and returned to a normal but magnetically ordered state between the temperature range of 0.3 K and 0.53 K. The main objective of this work is to show the temperature dependence of the upper critical magnetic field of superconducting HoMo6Se8 by using the Ginzburg-Landau (GL) phenomenological Equation. We found the direct relationship between the GL coherence length (ξGL) and penetration depth (λGL) with temperature. From the GL Equations and the results obtained for the GL coherence length, the expression for upper critical magnetic field (Hc2) is obtained for the superconducting HoMo6Se8. The result is plotted as a function of temperature. The graph shows the linear dependence of upper critical magnetic field (Hc2) with temperature (T) and our finding is in agreement with experimental observations.
The Effects of Student-Centered Approach in Improving Students’ Graphical Interpretation Skills and Conceptual Understanding of Kinematical Motion
Ambelu Tebabal,Gebregziabher Kahssay
Latin-American Journal of Physics Education , 2011,
Abstract: This study investigated the effect of student-centered instruction in improving students graphical interpretation skills and conceptual understanding of kinematical motion in Bistu Gebre Michael Catholic general and preparatory school found in Bahir Dar town of Amhara National Regional State, Ethiopia. A total of 77 (39 female and 38 male) grade nine students were involved in the study. The design adopted in the study was non-randomized pre-test and post-test control group design. The instrument used in gathering data for the study was background survey, Graphical Interpretation Skill Test (GIST) and Motion Content Test (MCT). Chi-square ( 2) and t-test were used as statistical analysis. The internal reliability coefficient of the test was 0.73 using Kuder Richardson Formula-20 (KR-20). The result showed that studentcentered instruction was found to be more promising in improving students graphical interpretation skill and conceptual understanding of kinematical motion.
Why People Strive to Get Rid of One’s Own Gene from the World? A Psychological Analysis upon Terrorism  [PDF]
Kahsay Weldeslasie Hailemariam
Open Access Library Journal (OALib Journal) , 2016, DOI: 10.4236/oalib.1102248
Abstract: Everybody remembers the April 19/2015 holocaust action committed by the ISIS terrorist group upon the Ethiopian Emigrants in the Libyan port. It was very immoral and devil action to behead and shoot people for the reason they do not know. In addition to that, it was the recent events to remember back about the massacre actions committed upon the France journalists and college students in Kenya who killed by the terrorist groups. For this inhuman and brutal action of the terrorist group, I initiated to make psychological analysis behind their behavior. I was also very eager to read different research findings about the true origin of human difference and why people strive to eliminate their own gene from the earth attributing human made differences. These and other questions are triggered me to make this psychological analysis. In the near future I will come up with detail investigation upon psychological view of terrorism.
Antibiotic Resistant Bacteria from Treated and Untreated Hospital Wastewater at Ayder Referral Hospital, Mekelle, North Ethiopia  [PDF]
Tsegahun Asfaw, Letemichael Negash, Amlsha Kahsay, Yemane Weldu
Advances in Microbiology (AiM) , 2017, DOI: 10.4236/aim.2017.712067
Abstract: The widespread emergence of antibiotic resistance among bacterial pathogens has become one of the most serious challenges in Ethiopia. This study determined the prevalence and drug resistance patterns of bacterial pathogens isolated from treated and untreated wastewater released from Ayder Referral Hospital in Northern Ethiopia. A cross sectional study design was conducted from September-December, 2015 in wastewater released from Ayder referral hospital. A total of 40 composite samples were aseptically collected, transported and processed for enumeration of indicator organisms, bacteriological identification and susceptibility testing following standard procedure. Data obtained were entered and analyzed using SPSS version 20. Mean heterotrophic plate count, total coliform count, fecal coliform count and E. coli count were found to be 1.6 × 106 CFU/mL, 2.2 × 106 CFU/100 mL, 2.0 × 105 CFU/100 mL and 1.1 × 104 CFU/100 mL from treated wastewater respectively. Among the total samples 134 bacterial isolates were detected and [84 (62.7%)] were from untreated wastewater and [50 (37.3%)] were from treated wastewater. The most frequently isolated bacteria from untreated wastewater samples was Klebsiella spp [14 (16.7%)] followed by S. aureus [13 (15.5%)] and P. aeruginosa [12 (14.3%)], similarly in treated wastewater samples Klebsiella spp [10 (20%)], P. aeruginosa [8 (16%)] and S. aureus [8 (16%)] were frequently detected. The overall multi-drug resistance (MDR) in this study was [79/134 (79.1%)]. MDR from untreated wastewater sample was [64/84 (76.2%)] while from treated wastewater sample was [42/50 (84%)] and shows significant difference with (COR: 1.64, 95% CI: 1.15 - 3.29, P: 0.001). It is concluded that treated hospital wastewater contains large numbers of antibiotic resistant bacteria. Therefore, there should be continuous monitoring and evaluation of the effluent quality of the ponds and chlorination of the final effluent should be developed.
Quality Assessment of the Commonly Prescribed Antimicrobial Drug, Ciprofloxacin Tablets, Marketed in Tigray, Ethiopia
G Kahsay, A G/Egziabher
Momona Ethiopian Journal of Science , 2010,
Abstract: An attempt was made to assess the quality and compare the physicochemical equivalence of six brands of ciprofloxacin tablets marketed in Tigray, Ethiopia. Six brands of ciprofloxacin tablets were used in the study. Identity, weight uniformity test, disintegration test, dissolution test and assay for the content of active ingredients were performed using the methods described in the British Pharmacopoeia. All the samples passed the identity, disintegration, and dissolution tests but Ciflox failed to release 80% of the drug content within 30 minutes as stipulated in the pharmacopoeia. This product therefore does not comply with the BP 2004 dissolution tolerance limits. All of the brands examined pass the assay for content of active ingredient. This work revealed that the six brands included in the study complied with the physicochemical quality parameters except Ciflox which failed to meet the pharmacopoeial specification for dissolution test. Nevertheless the six brands showed that there is significant difference in the drug release in vitro (p<0.05). To justify the specification limits of the in vitro dissolution test, an attempt should be made to establish a meaningful correlation between in vitro release characteristics and in vivo bioavailability parameters.
Fitting parametric random effects models in very large data sets with application to VHA national data
Gebregziabher Mulugeta,Egede Leonard,Gilbert Gregory E,Hunt Kelly
BMC Medical Research Methodology , 2012, DOI: 10.1186/1471-2288-12-163
Abstract: Background With the current focus on personalized medicine, patient/subject level inference is often of key interest in translational research. As a result, random effects models (REM) are becoming popular for patient level inference. However, for very large data sets that are characterized by large sample size, it can be difficult to fit REM using commonly available statistical software such as SAS since they require inordinate amounts of computer time and memory allocations beyond what are available preventing model convergence. For example, in a retrospective cohort study of over 800,000 Veterans with type 2 diabetes with longitudinal data over 5 years, fitting REM via generalized linear mixed modeling using currently available standard procedures in SAS (e.g. PROC GLIMMIX) was very difficult and same problems exist in Stata’s gllamm or R’s lme packages. Thus, this study proposes and assesses the performance of a meta regression approach and makes comparison with methods based on sampling of the full data. Data We use both simulated and real data from a national cohort of Veterans with type 2 diabetes (n=890,394) which was created by linking multiple patient and administrative files resulting in a cohort with longitudinal data collected over 5 years. Methods and results The outcome of interest was mean annual HbA1c measured over a 5 years period. Using this outcome, we compared parameter estimates from the proposed random effects meta regression (REMR) with estimates based on simple random sampling and VISN (Veterans Integrated Service Networks) based stratified sampling of the full data. Our results indicate that REMR provides parameter estimates that are less likely to be biased with tighter confidence intervals when the VISN level estimates are homogenous. Conclusion When the interest is to fit REM in repeated measures data with very large sample size, REMR can be used as a good alternative. It leads to reasonable inference for both Gaussian and non-Gaussian responses if parameter estimates are homogeneous across VISNs.
Immune restoration disease and changes in CD4+ T-cell count in HIV- infected patients during highly active antiretroviral therapy at Zewditu memorial hospital, Addis Ababa, Ethiopia
Kahsay Huruy, Afework Kassu, Andargachew Mulu, Yemataw Wondie
AIDS Research and Therapy , 2010, DOI: 10.1186/1742-6405-7-46
Abstract: A retrospective study of all HIV- infected patients starting HAART between September 1, 2005 and August 31, 2006 at Zewditu memorial hospital HIV clinic, Addis Ababa, Ethiopia was conducted. All laboratory and clinical data were extracted from computerized clinic records and patient charts.A total of 1166 HIV- infected patients with mean ± SD age of 36 ± 9.3 years were on HAART. IRD was identified in 170 (14.6%) patients. OIs diagnosed in the IRD patients were tuberculosis (66.5%, 113/170), toxoplasmosis (12.9%, 22/170), herpes zoster rash (12.9%, 22/170), Pneumocystis jirovecii pneumonia (4.1%, 7/170), and cryptococcosis (3.5%, 6/170). Of the 170 patients with IRD, 124 (72.9%) patients developed IRD within the first 3 months of HAART initiation. Low baseline CD4+ T-cell count (odds ratio [OR], 3.16, 95% confidence interval [CI], 2.19-4.58) and baseline extra pulmonary tuberculosis (OR, 7.7, 95% CI, 3.36-17.65) were associated with development of IRD. Twenty nine (17.1%) of the IRD patients needed to use systemic anti-inflammatory treatment where as 19(11.2%) patients required hospitalization associated to the IRD occurrence. There was a total of 8 (4.7%) deaths attributable to IRD.The proportion and risk factors of IRD and the pattern of OIs mirrored reports from other countries. Close monitoring of patients during the first three months of HAART initiation is important to minimize clinical deterioration related to IRD.Highly active antiretroviral therapy (HAART) improves the immune function and decreases morbidity, mortality and opportunistic infections (OIs) in HIV-infected patients [1,2]. However, the introduction of HAART presents new clinical problems, including adverse drug effects, and the event of diseases that are as the result of the restoration of the immune response. When clinical deterioration occurs during immune recovery and is associated with the host inflammatory response to pathogens, the clinical presentation has been described as immune restorat
Simulated Estimates of Pre-Pregnancy and Gestational Diabetes Mellitus in the US: 1980 to 2008
Maria E. Mayorga, Odette S. Reifsnider, David M. Neyens, Mulugeta G. Gebregziabher, Kelly J. Hunt
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0073437
Abstract: Purpose To simulate national estimates of prepregnancy and gestational diabetes mellitus (GDM) in non-Hispanic white (NHW) and non-Hispanic black (NHB) women. Methods Prepregnancy diabetes and GDM were estimated as a function of age, race/ethnicity, and body mass index (BMI) using South Carolina live singleton births from 2004–2008. Diabetes risk was applied to a simulated population. Age, natality and BMI were assigned to women according to race- and age-specific US Census, Natality and National Health and Nutrition Examination Surveys (NHANES) data, respectively. Results From 1980–2008, estimated GDM prevalence increased from 4.11% to 6.80% [2.68% (95% CI 2.58%–2.78%)] and from 3.96% to 6.43% [2.47% (95% CI 2.39%–2.55%)] in NHW and NHB women, respectively. In NHW women prepregnancy diabetes prevalence increased 0.90% (95% CI 0.85%–0.95%) from 0.95% in 1980 to 1.85% in 2008. In NHB women from 1980 through 2008 estimated prepregnancy diabetes prevalence increased 1.51% (95% CI 1.44%–1.57%), from 1.66% to 3.16%. Conclusions Racial disparities in diabetes prevalence during pregnancy appear to stem from a higher prevalence of prepregnancy diabetes, but not GDM, in NHB than NHW.
Quantifying the Impact of Gestational Diabetes Mellitus, Maternal Weight and Race on Birthweight via Quantile Regression
Caitlyn N. Ellerbe, Mulugeta Gebregziabher, Jeffrey E. Korte, Jill Mauldin, Kelly J. Hunt
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0065017
Abstract: Background Quantile regression, a robust semi-parametric approach, was used to examine the impact of gestational diabetes mellitus (GDM) across birthweight quantiles with a focus on maternal prepregnancy body mass index (BMI) and gestational weight gain (GWG). Methods Using linked birth certificate, inpatient hospital and prenatal claims data we examined live singleton births to non-Hispanic white (NHW, 135,119) and non-Hispanic black (NHB, 76,675) women in South Carolina who delivered 28–44 weeks gestation in 2004–2008. Results At a maternal BMI of 30 kg/m2 at the 90th quantile of birthweight, exposure to GDM was associated with birthweights 84 grams (95% CI 57, 112) higher in NHW and 132 grams (95% CI: 104, 161) higher in NHB. Results at the 50th quantile were 34 grams (95% CI: 17, 51) and 78 grams (95% CI: 56, 100), respectively. At a maternal GWG of 13.5 kg at the 90th quantile of birthweight, exposure to GDM was associated with birthweights 83 grams (95% CI: 57, 109) higher in NHW and 135 grams (95% CI: 103, 167) higher in NHB. Results at the 50th quantile were 55 grams (95% CI: 40, 71) and 69 grams (95% CI: 46, 92), respectively. Summary Our findings indicate that GDM, maternal prepregnancy BMI and GWG increase birthweight more in NHW and NHB infants who are already at the greatest risk of macrosomia or being large for gestational age (LGA), that is those at the 90th rather than the median of the birthweight distribution.
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