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Study of the Intrinsic Recombination Velocity at the Junction of Silicon Solar under Frequency Modulation and Irradiation

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Journal of Applied Mathematics and Physics 2015年第11期3卷 1522-1535页

作者： El Hadji ndiaye Gokhan Sahin Moustapha Dieng Amary Thiam Hawa Ly Diallo mor ndiaye Grégoire Sissoko Laboratory of Semiconductors and Solar Energy Physics Department Faculty of Science and Technology University Cheikh Anta Diop Dakar Senegal

In this study, a method for determining the intrinsic recombination velocity at the junction of a silicon solar cell is presented. The expression of intrinsic recombination velocity at the junction was established under irradiation in frequency modulation. Based on this expression, an electrical model of the intrinsic recombination velocity at the junction is presented.

关键词： Silicon Solar Cell Frequency Modulation Intrinsic Recombination Velocity at the Junction Irradiation Energy

Nuchal Cord at Delivery and Neonatal Outcomes: A Retrospective Cohort Study

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Open Journal of Obstetrics and Gynecology 2022年第4期12卷 285-291页

作者： Mbodji Aissatou Gueye Mamour Wade Mouhamadou ndiaye Mame Diarra Dia Aliou Djiby Cisse Aliou Ibrahim Rahadat ndiaye mor Talla Mbaye Magatte Philippe Maguilen Senghor Health Center Dakar Sénégal Cheikh Anta Diop Univeristy Dakar Sénégal Gaston Berger University Saint-Louis Sénégal

Objective: The present study was aimed at evaluating the outcome of pregnancies with a nuchal cord. Methods: A retrospective population-based study of all deliveries during the years 2011-2020 in Philippe Maguilen SENGHOR Center was conducted. Perinatal outcome of patients with and without nuchal cord was compared. Results: Among 44,958 deliveries during the study period, 1.8% had a nuchal cord, documented at birth (n = 807). Higher rates of labor induction (9.1% vs. 3.2%;p 0.001) and non-reassuring fetal heart rate patterns (RR = 2.366;CI: 1.631 - 3.432) were noted among pregnancies with nuchal cord as compared with the control group. The cesarean delivery rate was significantly higher among pregnancies with a nuchal cord (39.5% vs. 21.8%;RR = 2333;CI: 2.023 - 2.692). Although 5 min Apgar scores lower than 7 were more common in pregnancies with a nuchal cord (7.8% vs. 3.8%;RR = 2.117;CI: 1.629 - 3.363). There was no statistical significance between the two groups for the perinatal mortality. Conclusion: Nuchal cord is associated with prolonged labor and adverse perinatal outcome.

关键词： Nuchal Cord Perinatal Outcome Philippe Senghor Health Center Dakar

Diffusion Coefficient in Silicon Solar Cell with Applied Magnetic Field and under Frequency: Electric Equivalent Circuits

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World Journal of Condensed Matter Physics 2014年第2期4卷 84-92页

作者： Amadou Diao Ndeye Thiam Martial Zoungrana Gokhan Sahin mor ndiaye Grégoire Sissoko Laboratory of Environment Materials Physics Department Training and Research Unit in Applied Science University of Ouagadougou Ouagadougou Burkina Faso Laboratory of Semiconductors and Solar Energy Physics Department Faculty of Science and Technology University Cheikh Anta Diop Dakar Sénégal

In this paper, a theory on the determination of the diffusion coefficient of excess minority carriers in the base of a silicon solar cell is presented. The diffusion coefficient expression has been established and is related to both frequency modulation and applied magnetic field;the study is then carried out using the impedance spectroscopy method and Bode diagrams. From the diffusion coefficient, we deduced the diffusion length and the minority carriers’ mobility. Electric parameters were derived from the diffusion coefficient equivalent circuits.

关键词： Solar Cell Magnetic Field Frequency Modulation Diffusion Coefficient

Profile of Workers Tested Positive for Sars-CoV-2 in Sangalkam Health District (Senegal)

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Health 2021年第11期13卷 1278-1284页

作者： Bocar Baïla Diedhiou Jean Augustin Diegane Tine Mohamed Diabate Ibrahima Seck mor ndiaye Dakar Medical Region MSAS Dakar Senegal SMPSP FMPO UCAD Dakar Senegal University of Lyon Lyon France SOHD FMPO-UCAD Dakar Senegal

Background: COVID-19 has shown the vulnerability of our healthcare staff in terms of exposure. Staff contamination is a reality to be explored and prevented. Objective: It was to describe the epidemiological, clinical, therapeutic and evolutionary profiles of health staff infected with COVID-19 in the Health District of Sangalkam (Senegal). Materials and Methodologies: This was a retrospective study from April 1, 2020 to April 20, 2021. District health staff tested positive of Sars-CoV-2 were included. Results: Sixty-six professionals were sampled, of whom seventeen were positive (25.8%). The medical history found was diabetes type 2 (n = 1) and hypertension/obesity (n = 1). Only one victim had previously received an incomplete vaccination. The average age of the infected personnel was 38.4 years. Victims with an identified epidemiological link were more numerous (64.7%). Respiratory signs (cough, rhinorrhea) and fever predominated. Caregivers accounted for 76% of the victims, compared with 26% of the administrative staff. Most patients were followed at home (76.4%). One severe case was admitted to the intensive care unit. The recovery rate was 100%. The average length of absence was 13 days. Conclusion: Infection of the staff is of great concern. Regular and decontamination and systematic cleaning of consultation offices and hospital wards are necessary. In addition, vaccination, screening, strict compliance with barrier measures (wearing masks, hand washing, physical distancing).

关键词： Workers Sars-CoV-2 COVID-19 Health-District Senegal

Assessment of Obstetric Evacuations: Received during the Year 2020 at the Touba Ndamatou Public Health Hospital Establishment

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Open Journal of Obstetrics and Gynecology 2022年第6期12卷 528-540页

作者： Babacar Biaye Mouhamadou Wade Daba Diop Abdou Karim Diallo mor ndiaye Alioune Diop Awa ndiaye Mamadou Sene Abdoul Aziz Diouf Mamour Gueye Université Cheikh Anta Diop Dakar Senegal

The counter-referral system is particularly important for care during pregnancy, childbirth and the post-partum period as it facilitates access to emergency obstetric and neonatal care. It allows people to access care that is not likely to be provided at the base and to manage certain complications arising in emergency settings. We therefore looked at the evaluation of obstetric evacuations from the Touba Ndamatou public health. Methodology: This was a retrospective study of descriptive and analytical type extending over a period of 12 months from January 1, 2020 to December 31, 2020 at the public hospital health establishment (PHHE) of Touba Ndamatou. Results: One thousand five hundred and sixty (1560) patients evacuated for obstetrical reasons were collected out of a total admission of 5560, i.e., a frequency of 28%. The average age of the patients was 25.54 years. The mean gestation was 3.24 pregnancies. The average parity was 3.04 deliveries. Almost all of our patients (99%) were married. Slightly more than one in two women (53.6%) had performed at least 2 or 3 Prenatal consultations. 80% of parturients had traveled a distance of less than 20 km. 623 patients came by their own means (54.6%). Evacuation was provided by an ambulance in 509 patients, i.e., 44.6%. Arterial hypertension and its complications were the frequent reason for evacuations with approximately one in four patients (26.2%). Only 3.6% of patients had qualified personnel on board being evacuated. In our series, 13 deaths were recorded, i.e., 1.1% of cases. The distance traveled seemed not to influence the future of the mother (p = 0.51). The non-accompaniment of the patient during the evacuation by a medical staff seemed to influence the prognosis of the mother (p = 0.031). Fetal morbidity was higher among evacuees not accompanied by medical personnel. The state of apparent death was observed in the majority of cases in patients received over a distance of more than 20 km. Conclusion: Evacuation

关键词： Evacuation Pregnancy Senegal

Occupational Hearing Hazards among Informal Sector Welders in Lubumbashi, Democratic Republic of Congo

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Health 2021年第9期13卷 995-1009页

作者： Nowa Mutangala mor ndiaye André Ngombe Kaseba Clarence Mukeng Philippe Mulenga Cilundika Eric Sompwe Mukomena Ruashi Mining Lubumbashi Democratic Republic of Congo (DRC) Occupational Medicine Service Faculty of Medicine University Cheikh Anta Diop (UCAD) Dakar Senegal School of Public Health University of Lubumbashi Lubumbashi Democratic Republic of Congo Department of Public Health School of Medicine University of Lubumbashi Lubumbashi Democratic Republic of Congo

Introduction: Noise, an undesirable sound which is found in all areas of occupational activity, is still a matter of concern given the damage it causes. Various machines and tools, from simple to sophisticated ones, produce several types of noise in the workplace. The purpose of this study was to assess the current status of occupational hearing loss among informal sector welders in the city of Lubumbashi, in the Democratic Republic of Congo. Methods: This was a descriptive cross-sectional study which was conducted among 122 informal sector welders over a period of five months. The study used an anonymous questionnaire on noise exposure in the workplace and collected audio-metric data of welders. The survey collected data on welders who had a minimal three-year duration of employment without the morbidity associated with the Ear Nose Throat (ENT) region. Socio-professional data (age, duration of employment, sex, education), noise exposure, awareness of hazards and audiometric data were taken into account. Results: 122 questionnaires were completed by male subjects, or 100% (n = 122). The mean age of welders was 36.37 ± 11.91 years with extremes being 20 and 63 years. The mean duration of employment was 11.51 ± 9.6 years with extremes being 3 and 44 years. Audiometric data have shown 37.96% (n = 41) of occupational hearing loss. Three degrees of hearing loss were recorded, notably mild hearing loss standing at 80.49% (n = 33);moderate and severe hearing loss standing at 2.44% (n = 1). Ninety-six percent (n = 117) of welders reported not using personal protective equipment (PPE) and 1% (n = 111) were aware of the hazard associated with noise exposure in the workplace. A correlation was found between welders with an advanced age (p Conclusion: In the study are

关键词： Audiometry Informal Sector Welders Lubumbashi DRC

Back Illuminated N/P/P+Bifacial Silicon Solar Cell under Modulated Short-Wavelength: Determination of Base Optimum Thickness

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Energy and Power Engineering 2021年第5期13卷 207-220页

作者： Mamadou Sall Dianguina Diarisso Mame Faty Mbaye Fall Gora Diop mor ndiaye Khady Loum Gregoire Sissoko Laboratory of Semiconductors and Solar Energy Physics Department Faculty of Science and Technology Cheikh Anta Diop University Dakar Senegal University Institute of Technology University of Thiès Thiès Sénégal Ecole Polytechnique de Thiès Thiès Sénégal

A bifacial silicon solar cell under monochromatic illumination in frequency modulation by the rear side is being studied for the optimization of base thickness. The density of photogenerated carriers in the base is obtained by resolution of the continuity equation, with the help of boundary conditions at the junction surface (n+/p) and the rear face (p/p+) of the base. For a short wavelength corresponding to a high absorption coefficient, the AC photocurrent density is calculated and represented according to the excess minority carrier’s recombination velocity at the junction, for different modulation frequency values. The expression of the AC recombination velocity of excess minority carriers at the rear surface of the base of the solar cell is then deduced, depending on both, the absorption coefficient of the silicon material and the thickness of the base. Compared to the intrinsic AC recombination velocity, the optimal thickness is extracted and modeled in a mathematical relationship, as a decreasing function of the modulated frequency of back illumination. Thus under these operating conditions, a maximum short-circuit photocurrent is obtained and a low-cost bifacial solar cell can be achieved by reducing material (Si) to elaborate the base thickness.

关键词： Bifacial Silicon Solar Cell AC Recombination Velocity-Base Thickness Short-Wavelength

n+-p-p+Silicon Solar Cell Base Optimum Thickness Determination under Magnetic Field

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Journal of Electromagnetic Analysis and Applications 2020年第7期12卷 103-113页

作者： Cheikh Thiaw Mamadou Lamine Ba Mamour Amadou Ba Gora Diop Ibrahima Diatta mor ndiaye Gregoire Sissoko Laboratory of Semiconductors and Solar Energy Physics Department Faculty of Science and Technology University Cheikh Anta Diop Dakar Senegal

Base optimum thickness is determined for a front illuminated bifacial silicon solar cell n+-p-p+ under magnetic field. From the magneto transport equation relative to excess minority carriers in the base, with specific boundary conditions, the photocurrent is obtained. From this result the expressions of the carrier’s recombination velocity at the back surface are deducted. These new expressions of recombination velocity are plotted according to the depth of the base, to deduce the optimum thickness, which will allow the production, of a high short-circuit photocurrent. Calibration relationships of optimum thickness versus magnetic field were presented according to study ranges. It is found that, applied magnetic field imposes a weak thickness material for solar cell manufacturing leading to high short-circuit current.

关键词： Silicon Solar Cell Magnetotransport Surface Recombination Velocity Base Thickness

Assessment of Total Incapacity for Work or Incapacity in the Criminal Sense in Case of Penetrating Wounds of the Neck

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Forensic Medicine and Anatomy Research 2018年第1期6卷 1-9页

作者： El Hadji Oumar Ndoye Bobo Diallo Sidy Ahmed Dia Mouhamed Manibiliot Soumah Mame Coumba Fall mor ndiaye Department of Forensic and Labor Medicine University Cheikh Anta Diop (UCAD) Dakar Senegal ENT Department of the University Hospital Center of Fann Dakar Senegal

Penetrating wounds of the neck are often life-threatening. The victims are exposed to vascular and laryngotracheal lesions. The purpose of this work is to report the various aspects of the management of penetrating wounds in our context and to make the medico-legal assessment of incapacity in the criminal sense or total incapacity for work. This is a retrospective study (2002-2014) on thirty-nine (39) cases of penetrating neck wounds, received at the ENT departments of the Aristide Le Dantec and Fann University Hospital Centers. Patients were predominantly male, representing 94% of cases with an average age of 27 years. Seventy (70%) of the accidents occurred in the region of Dakar. In 42% of cases, the circumstance of occurrence was a fight or an assault. The weapon used in most cases by the aggressor was a cutter or a knife. The average waiting time was 37 hours with extremes of 02 and 216 hours. Surgically, all patients had been examined under general anesthesia. In terms of lesions, 37 cases had profound cervical muscle injuries, i.e. 94%. There were 17 vascular lesions (43%). The medico-legal distribution of patients showed that among them, 10% had a total incapacity to work exceeding 21 days. The determination of total incapacity for work is an important medical procedure that requires capability and experience. The doctor must not fall into the trap of the confusion between the TIW on the criminal level and the TIW on the civil level. He must limit medically and should not make judgments.

关键词： Penetrating Neck Wounds Assessment of Total Incapacity for Work Criminal Incapacity Forensic Medicine