Gender diversity and earnings management: the case of female directors with financial background

Past evidence generally suggests that the presence of female directors on corporate boards tends to improve earnings quality due to these directors’ superior monitoring abilities. However, it is not clear which characteristics and skills of female directors drive such abilities. In this paper, we focus on the financial background of female directors, an area which remains largely unexplored in existing literature. The results show that the participation of female directors with relevant financial background improves earnings quality more than the participation of female directors without such background. In addition, our findings suggest that only female directors possessing relevant financial background and having fewer outside directorships are able to mitigate earnings management and therefore overcommitting expert female directors with more outside directorships would diminish their monitoring ability. We did not find any evidence suggesting that female directors without relevant financial background are able to mitigate earnings management, irrespective of their outside directorships or tenure. We interpret our findings within a theoretical framework that draws on a number of economic and social theories. The results are generally robust after controlling for potential endogeneity problems

Estudio numérico de la convección natural en un anillo

En este artículo, se ha investigado numéricamente la transmisión térmica por convección libre laminar en 2-D. Se estudiaron recintos rectangulares concéntricos dobles con calentadores discretos utilizando el paquete de software COMSOL Multiphysics 6.0. Se aplicó el flujo de calor utilizando un número específico de calentadores, así como cambiando el número y las distancias de los calentadores en cada caso. Los calentadores se instalaron en la pared vertical izquierda del recinto; la pared opuesta se mantuvo a temperatura constante. Las paredes horizontales se consideraron adiabáticas. Se tomó el aire como fluido de trabajo y todas las características del aire se consideraron constantes excepto el cambio de densidad debido a las fuerzas de flotabilidad que impulsan el fluido. Se eligió el método de volúmenes finitos para resolver las ecuaciones gobernantes en la fórmula adimensional. Se analizó el efecto del número de Rayleigh en el número de Nusselt utilizando los contornos isotérmicos resultantes. Obtuvimos los resultados para diferentes valores del número de Rayleigh. Se logró una gran mejora en la transmisión térmica en los resultados obtenidos; se encontró que la cantidad de energía térmica transmitida aumentará al aumentar el valor de Ra

The Effective M3Y Residual Interaction In 41Ca As a Nuclear Diffraction Grating of Electrons

تمت تحقيق عوامل التشكل للاستطارة الالكترونية المغناطيسية المرنة متعددة الاقطاب الكلية والمنفردة  لنظير 41Ca باستخدام أنموذج القشرة النووية الناجح و الواسع التطبيق واعتبار الغلاف 1f7/2 كأنموذج فضاء واعتماد التفاعلF7MBZ    كتفاعل مؤثر لتشكيل دوال موجة انموذج الفضاء. اعتمدت دالة المتذبذب التوافقي كدالة جسيم منفرد , كما تم اعتماد نواة 40Ca كقلب خامل حيث يتم استقطابه واشراكه في حسابات عوامل التشكل المغناطسية المرنة من خلال عملية استقطاب القلب حيث يتم خلع نيوكليون من مدارات القلب الخامل وتهييجه الى مستويات عليا وبفرق طاقة 2ћω وكما تم الاعتماد على التفاعل الواقعي (effective M3Y P2) في حسابات استقطاب القلب والذي يفاعل الزوج( جسيم –فجوة ) ان هذا التفاعل هو نموذج مطور حديثا للتفاعل الاصلي واخيرا تم مقارنة النتائج النظرية مع ما هو متوفر من نتائج عملية.The total and individual multipole moments of  magnetic electron scattering form factors in 41Ca  have been investigated using a widely successful model which is the nuclear shell model configurations keeping in mind of 1f7/2 subshell as an L-S shell and Millinar, Baymann, Zamick as L-S shell (F7MBZ) to give the model space  wave vector. Also, harmonic oscillator wave functions have been used as wave function of a single particle in 1f7/2  shell. Nucleus 40Ca as core closed and Core polarization effects have been used as a corrective with first order correction concept to basic computation of L-S shell and the excitement energy has been implemented with 2ћω. The core polarizability effect has been utilized to incorporate the rejected space (core + higher arrangement) via L-S shell with a realism interaction of effective M3Y P2 interaction to connect the model space particles in motion with the spouse (p-h). The two body M3Y interactions have been utilized as an interaction residue to calculate the core polarizability matrix elements. Finally, the theoretical result of the form factor has been compared with the experimental results

Improving Flexural Behavior of Textile Reinforced Concrete One Way Slab by Removing Weft Yarns with Different Percentages

Textile reinforced concrete that developed at recent years is composed of the continuous textile fabric incorporated into the cementitious matrix. The geometry of the textile reinforcements has a great influence on the TRC overall behavior since it affects the bond efficiency perfectly. The effect of weft yarns removing on the flexural behavior of (1500 × 500 × 50) mm one way slabs was investigated, eight layers of the carbon fabric were used with (50%, 67% and 75%) removing of weft yarns in addition to one specimen without removing. The four one- way slabs were casted by hand lay-up method, cured for (28) days and tested in flexure using four points method. The bending capacity and the bond efficiency factor were calculated according to the conditions of the equilibrium models by comparing with experimental results. The results revealed that with higher removing proportion there was a perfect improvement in the flexural capacity, higher first crack load, eminent post cracking stiffness, higher average concrete strain and lower ultimate mid span deflection and higher toughness and ductility. Furthermore, the results clarified that there is an optimum percent of weft yarns removing at which the damage occurrence around the weft yarns is significantly reduced, and this negative effect constriction overcome the positive anchoring effect

Activated Carbon from Mangrove Wood (Rizophora apiculata): Preparation and Characterization

Activated carbon was prepared from mangrove wood (Rizophora apiculata) by destructive distillation in vacuum. A series of heating times and temperatures were selected for the preparation of activated carbon. The iodine number of the activated carbon was determined by absorption method in aqueous solution. The plot of iodine number as a function of heating temperature revealed that the maximum iodine number was attained at 500·C after heating for 3 hours. Determination of trace elements, pore sizes and surface topography was also carried out

Comparative Analysis of MFO, GWO and GSO for Classification of Covid-19 Chest X-Ray Images

تلعب الصور الطبية دورًا حاسمًا في تصنيف الأمراض والحالات المختلفة. إحدى طرق التصوير هي الأشعة السينية التي توفر معلومات بصرية قيمة تساعد في تحديد وتوصيف مختلف الحالات الطبية. لطالما استخدمت الصور الشعاعية للصدر (CXR) لفحص ومراقبة العديد من اضطرابات الرئة، مثل السل والالتهاب الرئوي وانخماص الرئة والفتق. يمكن الكشف عن COVID-19 باستخدام صور CXR أيضًا. تم اكتشاف COVID-19، وهو فيروس يسبب التهابات في الرئتين والممرات الهوائية في الجهاز التنفسي العلوي، لأول مرة في عام 2019 في مقاطعة ووهان بالصين، ومنذ ذلك الحين يُعتقد أنه يتسبب في تلف كبير في مجرى الهواء، مما يؤثر بشدة على رئة الأشخاص المصابين. انتشر الفيروس بسرعة في جميع أنحاء العالم، وتم تسجيل الكثير من الوفيات والحالات المتزايدة بشكل يومي. يمكن استخدام CXR لمراقبة آثار COVID-19 على أنسجة الرئة. تبحث هذه الدراسة في تحليل مقارنة لأقرب جيران k (KNN)، و Extreme Gradient Boosting (XGboost)، و Support-Vector Machine (SVM)، وهي بعض مناهج التصنيف لاختيار الميزات في هذا المجال باستخدام خوارزمية Moth-Flame Optimization (MFO)، وخوارزمية Gray Wolf Optimizer (GWO)، وخوارزمية Glowworm Swarm Optimization (GSO). في هذه الدراسة، استخدم الباحثون مجموعة بيانات تتكون من مجموعتين على النحو التالي: 9544 صورة بالأشعة السينية ثنائية الأبعاد، والتي تم تصنيفها إلى مجموعتين باستخدام اختبارات التحقق من صحتها: 5500 صورة لرئتين سليمتين و4044 صورة للرئتين مع COVID-19. تتضمن المجموعة الثانية 800 صورة و400 صورة لرئتين سليمتين و400 رئة مصابة بـ COVID-19. تم تغيير حجم كل صورة إلى 200 × 200 بكسل. كانت الدقة والاستدعاء ودرجة F1 من بين معايير التقييم الكمي المستخدمة في هذه الدراسة.Medical images play a crucial role in the classification of various diseases and conditions. One of the imaging modalities is X-rays which provide valuable visual information that helps in the identification and characterization of various medical conditions. Chest radiograph (CXR) images have long been used to examine and monitor numerous lung disorders, such as tuberculosis, pneumonia, atelectasis, and hernia. COVID-19 detection can be accomplished using CXR images as well. COVID-19, a virus that causes infections in the lungs and the airways of the upper respiratory tract, was first discovered in 2019 in Wuhan Province, China, and has since been thought to cause substantial airway damage, badly impacting the lungs of affected persons. The virus was swiftly gone viral around the world and a lot of fatalities and cases growing were recorded on a daily basis. CXR can be used to monitor the effects of COVID-19 on lung tissue. This study examines a comparison analysis of k-nearest neighbors (KNN), Extreme Gradient Boosting (XGboost), and Support-Vector Machine (SVM) are some classification approaches for feature selection in this domain using The Moth-Flame Optimization algorithm (MFO), The Grey Wolf Optimizer algorithm (GWO), and The Glowworm Swarm Optimization algorithm (GSO). For this study, researchers employed a data set consisting of two sets as follows: 9,544 2D X-ray images, which were classified into two sets utilizing validated tests: 5,500 images of healthy lungs and 4,044 images of lungs with COVID-19. The second set includes 800 images, 400 of healthy lungs and 400 of lungs affected with COVID-19. Each image has been resized to 200x200 pixels. Precision, recall, and the F1-score were among the quantitative evaluation criteria used in this study

COVID-19 Mathematical Study with Environmental Reservoir and Three General Functions for Transmissions

In this paper, the ongoing new coronavirus (COVID-19) epidemic is being investigated using a mathematical model. The model depicts the dynamics of infection with several transmission pathways and general infection functions, plus it highlights the significance of the environment as a reservoir for the disease’s propagation and dissemination. We have studied the qualitative behavior of the proposed model representing a system of fractional differential equations. Under a set of conditions on the general functions and the parameters, we have proven the global asymptotic stability of all steady states by using the Lyapunov method and LaSalle’s invariance principle. We also carried some numerical results to confirm the analytical results we obtained

Resource Management Techniques in Cloud-Fog for IoT and Mobile Crowdsensing Environments

The unpredictable and huge data generation nowadays by smart devices from IoT and mobile Crowd Sensing applications like (Sensors, smartphones, Wi-Fi routers) need processing power and storage. Cloud provides these capabilities to serve organizations and customers, but when using cloud appear some limitations, the most important of these limitations are Resource Allocation and Task Scheduling. The resource allocation process is a mechanism that ensures allocation virtual machine when there are multiple applications that require various resources such as CPU and I/O memory. Whereas scheduling is the process of determining the sequence in which these tasks come and depart the resources in order to maximize efficiency. In this paper we tried to highlight the most relevant difficulties that cloud computing is now facing. We presented a comprehensive review of resource allocation and scheduling techniques to overcome these limitations. Finally, the previous techniques and strategies for allocation and scheduling have been compared in a table with their drawbacks

Resource Management Techniques in Cloud-Fog for IoT and Mobile Crowdsensing Environments

The unpredictable and huge data generation nowadays by smart devices from IoT and mobile Crowd Sensing applications like (Sensors, smartphones, Wi-Fi routers) need processing power and storage. Cloud provides these capabilities to serve organizations and customers, but when using cloud appear some limitations, the most important of these limitations are Resource Allocation and Task Scheduling. The resource allocation process is a mechanism that ensures allocation virtual machine when there are multiple applications that require various resources such as CPU and I/O memory. Whereas scheduling is the process of determining the sequence in which these tasks come and depart the resources in order to maximize efficiency. In this paper we tried to highlight the most relevant difficulties that cloud computing is now facing. We presented a comprehensive review of resource allocation and scheduling techniques to overcome these limitations. Finally, the previous techniques and strategies for allocation and scheduling have been compared in a table with their drawbacks