What are the disadvantages of Cox proportional hazard models as predictive health models?5 answersCox proportional hazards models, while popular in biomedical data analysis, face challenges when applied to high-dimensional data. Commonly used group sparse regularization can lead to excess smoothing shrinkage, impacting predictive performance. Additionally, the "all-in-all-out" approach complicates functional selection, especially in the presence of nonlinear effects. Validation of survival outcome models, like Cox regression models, is complex due to censoring and varying prediction timeframes. These models require thorough validation to assess performance accurately. Despite efforts to enhance flexibility through additive functions, extending Cox models to high-dimensional data remains nontrivial, necessitating innovative approaches like spike-and-slab LASSO priors for bi-level functional selection.
What is the concebtric zone model by ernest burgess?5 answersErnest Burgess introduced the concentric zone model in 1925, which serves as a fundamental framework for understanding urban social organization in American cities. This model depicts a city with distinct zones radiating outward from the central business district, each characterized by specific land use and socio-economic patterns. Burgess' model has been influential in urban research, particularly in studying the residential locations of different ethnic and occupational groups. Despite criticisms regarding its universal applicability, the model's heuristic value remains significant, guiding studies on urban growth and residential segregation. Burgess' model has inspired further research on urban development, with adaptations and extensions to accommodate diverse city structures and demographic dynamics.
What are the challenges of Free trade zone?4 answersFree trade zones face various challenges. One challenge is the subjugation of state interests to supranational institutions and laws, as seen in the EU and NAFTA. Another challenge is the need for these zones to be integrated into high-tech industrial transformation policies. Additionally, the development of free trade zones may face challenges such as the weakness of logistical capabilities and trade-related infrastructure, political instability in African countries, and the dependence of Algerian products on imported inputs. The African Continental Free Trade Zone also faces challenges, including the need to integrate African markets, stimulate industrialization, and promote free movement of goods, services, capital, and people. These challenges highlight the importance of addressing issues related to state interests, industrial transformation, infrastructure, political stability, and competitiveness to ensure the success of free trade zones.
Why people suggest Geocentric model?5 answersThe geocentric model was suggested because it was believed to explain the motion of celestial bodies in a way that aligned with observations and religious beliefs. This model placed the Earth at the center of the universe, with the Sun, Moon, and planets orbiting around it. The idea of a geocentric model can be traced back to ancient civilizations, such as the Greeks and Egyptians, who observed the apparent motion of the Sun and stars across the sky. They interpreted these observations as evidence that the Earth was stationary and everything else revolved around it. This view was also supported by religious texts, which described the Earth as the center of creation. However, with the advancement of scientific knowledge and the development of heliocentric models, such as the one proposed by Copernicus, the geocentric model was eventually replaced.
What are the challenges of creating and maintaining buffer zones?4 answersCreating and maintaining buffer zones face several challenges. In urban areas, the main challenge is mediating between the objectives of the protected area and providing environmental and social benefits. In sub-Saharan Africa, the needs of local populations for resource exploitation and conservation of protected areas are often not taken into account. Habitat fragmentation and connectivity maintenance are important considerations for buffer zone delimitation. In urban areas, conflicts arise between conservation and development interests, requiring a "win-win situation". Additionally, defining the boundaries of buffer zones around buried assets requires precise data and the generation of two-dimensional areas.
What is zone of inhibition?5 answersThe zone of inhibition refers to the clear area around a substance, such as an antibiotic or antimicrobial agent, on a culture plate where the growth of microorganisms is inhibited. It is a measure of the effectiveness of the substance in preventing the growth of bacteria or fungi. The diameter of the zone of inhibition is used to assess the inhibitory potency of the substance. The zone of inhibition assay is a commonly used method to determine the antimicrobial activity of various substances, including antimicrobial peptides (AMPs), fungi, phenol antimetabolites, and plant extracts. This assay involves placing a substance on a culture plate inoculated with microorganisms and measuring the diameter of the clear zone that forms around the substance. A larger zone of inhibition indicates a stronger inhibitory effect on microbial growth. The zone of inhibition assay is a simple and effective method for evaluating the antimicrobial properties of different compounds.