ARA-Homotopy Perturbation Technique with Applications

In this study, we propose a novel combination method between the ARA integral transform and the homotopy perturbation approach to solve systems of nonlinear partial differential equations. The difficulty arising in solving nonlinear partial differential equations could simply be overcome by using He’s polynomials during the application of the new method. The proposed technique can provide the solutions of the target problems without pre-assumptions or restrictive constrains in addition to avoiding the round-off errors. The efficiency of the new method is illustrated by applying it to solve different examples of systems of nonlinear partial differential equations. We discuss three interesting applications and solve them by the new approach, called ARA-homotopy perturbation method and get exact solutions, also the results are illustrated in figures

The Urban Morphology of Mshereib, the Heart of Downtown Doha

Doha experienced a remarkable transformation since oil and natural gas exportation began in the mid-twentieth century. Rapid urbanization and globalization ('process of interaction and integration among people, companies, and governments worldwide involving goods, services, data, technology, and capital') characterize this transformation. Doha expanded to accommodate significant population increases and lifestyle changes. The urban expansion was auto-centric and suburban, similar to post-war development in the United States and other western societies. Qatari citizens 'emptied' Old Doha as they moved to contemporary villas in new developments at the suburban periphery. In response, the Qatari government launched plans for Msheireb Downtown Doha. Its purpose is to attract Qataris back to Doha's historic center by providing a walkable, mixed-use urban environment promoting a new model of sustainable urbanism. The design and planning explicitly seek to become rooted in Qatari social identity while preserving cultural heritage and historic resources. Our paper investigates the urban form and function of Msheireb Downtown Doha to evaluate its success. It examines the urban morphology, including figure-ground and pedestrian sheds analysis from crucial locations and surveys of ground-level land uses, active/inactive frontages, and the pattern of building heights. The goal is to illustrate and understand the project's urban form and function logic. Based on this, we argue that Msheireb Downtown Doha does satisfy the inhabitants' desire for a downtown lifestyle. It offers a model for urban regeneration consistent with the Qatar National Vision 2030 for an advanced society, sustainable development, and a high standard of living for people.The authors acknowledge Qatar University and the Office of Research Support (ORS) for the grant, which covered portions of the research in this paper (Grant ID: QUCG-CENG-22/23/472)

NELF Potentiates Gene Transcription in the Drosophila Embryo

A hallmark of genes that are subject to developmental regulation of transcriptional elongation is association of the negative elongation factor NELF with the paused RNA polymerase complex. Here we use a combination of biochemical and genetic experiments to investigate the in vivo function of NELF in the Drosophila embryo. NELF associates with different gene promoter regions in correlation with the association of RNA polymerase II (Pol II) and the initial activation of gene expression during the early stages of embryogenesis. Genetic experiments reveal that maternally provided NELF is required for the activation, rather than the repression of reporter genes that emulate the expression of key developmental control genes. Furthermore, the relative requirement for NELF is dictated by attributes of the flanking cis-regulatory information. We propose that NELF-associated paused Pol II complexes provide a platform for high fidelity integration of the combinatorial spatial and temporal information that is central to the regulation of gene expression during animal development

LIF-Dependent Signaling: New Pieces in the Lego

LIF, a member of the IL6 family of cytokine, displays pleiotropic effects on various cell types and organs. Its critical role in stem cell models (e.g.: murine ES, human mesenchymal cells) and its essential non redundant function during the implantation process of embryos, in eutherian mammals, put this cytokine at the core of many studies aiming to understand its mechanisms of action, which could benefit to medical applications. In addition, its conservation upon evolution raised the challenging question concerning the function of LIF in species in which there is no implantation. We present the recent knowledge about the established and potential functions of LIF in different stem cell models, (embryonic, hematopoietic, mesenchymal, muscle, neural stem cells and iPSC). We will also discuss EVO-DEVO aspects of this multifaceted cytokine

Basin of Attraction through Invariant Curves and Dominant Functions

We study a second-order difference equation of the form zn+1=znF(zn-1)+h, where both F(z) and zF(z) are decreasing. We consider a set of invariant curves at h=1 and use it to characterize the behaviour of solutions when h>1 and when 0<h<1. The case h>1 is related to the Y2K problem. For 0<h<1, we study the stability of the equilibrium solutions and find an invariant region where solutions are attracted to the stable equilibrium. In particular, for certain range of the parameters, a subset of the basin of attraction of the stable equilibrium is achieved by bounding positive solutions using the iteration of dominant functions with attracting equilibria