Functional Characteristics of Four Novel Lone Atrial Fibrillation-Linked Connexin40 Mutants

Atrial fibrillation (AF) is the most common form of cardiac arrhythmia. Recently, four novel heterozygous Cx40 mutations, K107R, L223M, Q236H, and I257L were identified in 4 of 310 unrelated AF patients. To study possible alterations associated with these mutants, we studied their localization and function using gap junction (GJ)-deficient model cells. Cell pairs expressing Q236H alone or together with wildtype Cx43 showed a significantly lower coupling conductance. Impaired GJ function and dominant negative action on Cx43 of this mutant are consistent with previous findings on the majority of AF-linked Cx40 mutants. The remaining three novel AF-linked mutants did not show any apparent defects in our tested GJ or hemichannel assays, which may reflect the limitations of our experimental system

Investing in Entrepreneurship: The Sustainable Solution to Tunisia’s Youth Unemployment Crisis?

Since the Jasmine Revolution of 2011, Tunisia’s youth unemployment crisis has worsened. As of 2020, it has the tenth highest youth unemployment rate in the world at 36.5%. Experts have long identified this as the main challenge to overcoming Tunisia’s economic woes, and reform – from the education and vocational training systems on the supply-side to the job market on the demand-side – must follow the democratic gains achieved since 2011. The failed approach in reducing regional inequality under Ben Ali had an adverse effect, creating unemployment disparities between Tunisia’s affluent coastal cities and its poorer interior regions. As such, a pivotal remedy could well be found through a cohesive national youth entrepreneurship network that improves upon existing initiatives, the majority of which focus on university graduates in urban areas. While graduate unemployment is a real concern rooted in the inefficient education-job market nexus, youth entrepreneurship is a tool that can empower young citizens with limited education to build their own enterprises, potentially fostering a startup ecosystem that would transform the economic predicament of inner Tunisia. A concerted effort from government agencies, foreign development projects, and the private sector is necessary to develop a common national framework for entrepreneurial growth as well as the means to boost self-employment in the country’s most vulnerable communities. This will be equally important to reviving key industries like agriculture and mining, stimulating private sector enterprises and ultimately creating employment opportunities in economically detached regions

STUCK DRILL PIPE WHILE DRILLING OPERATION

Oil and companies spend about $20 billion annually on drilling. Unfortunately, not of that money is well spent. A significant portion, around 15%, is attributed to losses. These losses include loss of material, such as drilling equipment (Stuck pipe) and fluids, and loss of drilling process continuity, called nonproductive time (NPT). The objective s of this project are mainly concern and focusing about the downhoe problem during drilling operation in particularly the stuck pipe. The significant objectives of this project are: To measure the parameters that cause the stuck pipe such as Bit weight, coefficient of friction, rate of penetration ,drag and force and mud density To identify the potential formation that makes the stuck pipe by drilling fluid. The methodology of the project are first to have an ultimate background about the downhole problem and the causes that associated with stuck pipe, gathering necessary data for the analysis purpose and compare with the theoretical knowledge and to further conduct an experiment on the drilling fluid to configure the mud cake that mainly cause the differential stuck

Parametric Analysis of Resilient Modulus Modeling for Recycled Asphalt Pavement in Base Layer

The resilient modulus (MR) has been found to be the most important parameter in the Mechanistic-Empirical Pavement Design Guide (MEPDG) for the base layer. A literature review showed that the use of recycled asphalt pavement (RAP) in the base layer had many economic and structural benefits. The prediction of MR with the specific MEPDG model for the base layer mixed with RAP was found to be reliable for several field conditions. However, further studies of the MEPDG model are needed for an understanding of the physical meaning of each parameter in the model. The most important factor affecting MR for the base layer is the state of stresses, especially the confining pressure. This type of state of stresses was found in previous research to be more effective than deviator stresses. The present study focuses on the parametric analysis of each constant in the model versus various confining pressure states under various field conditions and at various RAP concentrations. This parametric analysis is compared with the traditional granular coarse aggregates used for the base layer before RAP is used so that any difference in the physical meaning when RAP is mixed in the base layer blend can be determined. The prediction of MR by the MEPDG model appears to be sound for RAP, but only with confining pressure levels below 10 psi and without significant variation in water content and maximum dry density. Freeze-thaw cycles do not negatively influence the prediction of MR for both RAP and granular coarse aggregates

Modeling of the Resilient Modulus for Recycled Asphalt Pavement Applications in Base Course Layers

The resilient modulus (MR) is an important parameter for the base course layer in the pavement design process. Use of recycled asphalt pavement (RAP) for this layer must take into consideration the effect of various factors that may occur in the field on the MR. Previous numerical models used for the granular base layer could be used for the RAP. The study reported here examined the suitability of RAP procedures under the effect of different factors (e.g., water content, dry density, freeze-thaw cycles). Various percentages of the RAP (50%, 75%, and 100% by weight) were employed in this research. All the models included in the study took into account the effect of state of stresses directly, but they also considered the other factors mentioned and the effect of their interactions with the MR indirectly. The intent of the study was twofold: (a) to determine the adequacy of the models employed in the use of the RAP procedure in the base course layer and (b) to determine which model best described RAP behavior under the effects of the tested factors. On the basis of a review of the literature, nine prediction models were chosen to investigate the granular base course layers so as to predict MR for RAP. A pilot analysis was made of these models to compare the measured and predicted values of MR under the tested factors. Three models showed a good prediction for the MR. These three models were reassessed in a sensitivity analysis on regression parameters to choose the best-fit model for the RAP applications