Measuring The Evolving Internet Ecosystem With Exchange Points

The Internet ecosystem comprising of thousands of Autonomous Systems (ASes) now include Internet eXchange Points (IXPs) as another critical component in the infrastructure. Peering plays a significant part in driving the economic growth of ASes and is contributing to a variety of structural changes in the Internet. IXPs are a primary component of this peering ecosystem and are playing an increasing role not only in the topology evolution of the Internet but also inter-domain path routing. In this dissertation we study and analyze the overall affects of peering and IXP infrastructure on the Internet. We observe IXP peering is enabling a quicker flattening of the Internet topology and leading to over-utilization of popular inter-AS links. Indiscriminate peering at these locations is leading to higher endto-end path latencies for ASes peering at an exchange point, an effect magnified at the most popular worldwide IXPs. We first study the effects of recently discovered IXP links on the inter-AS routes using graph based approaches and find that it points towards the changing and flattening landscape in the evolution of the Internet’s topology. We then study more IXP effects by using measurements to investigate the networks benefits of peering. We propose and implement a measurement framework which identifies default paths through IXPs and compares them with alternate paths isolating the IXP hop. Our system is running and recording default and alternate path latencies and made publicly available. We model the probability of an alternate path performing better than a default path through an IXP iii by identifying the underlying factors influencing the end-to end path latency. Our firstof-its-kind modeling study, which uses a combination of statistical and machine learning approaches, shows that path latencies depend on the popularity of the particular IXP, the size of the provider ASes of the networks peering at common locations and the relative position of the IXP hop along the path. An in-depth comparison of end-to-end path latencies reveal a significant percentage of alternate paths outperforming the default route through an IXP. This characteristic of higher path latencies is magnified in the popular continental exchanges as measured by us in a case study looking at the largest regional IXPs. We continue by studying another effect of peering which has numerous applications in overlay routing, Triangle Inequality Violations (TIVs). These TIVs in the Internet delay space are created due to peering and we compare their essential characteristics with overlay paths such as detour routes. They are identified and analyzed from existing measurement datasets but on a scale not carried out earlier. This implementation exhibits the effectiveness of GPUs in analyzing big data sets while the TIVs studied show that the a set of common inter-AS links create these TIVs. This result provides a new insight about the development of TIVs by analyzing a very large data set using GPGPUs. Overall our work presents numerous insights into the inner workings of the Internet’s peering ecosystem. Our measurements show the effects of exchange points on the evolving Internet and exhibits their importance to Internet routing

Pakistan: Prospects for Private Capital Flows and Financial Sector Development

In less than a decade after the debt crisis of 1982, developing countries have experienced a surge of capital inflows in recent years. This trend became more pronounced in the 1990s resulting in overall balance of payments surpluses and accumulation of reserves. Total private capital inflows to developing countries exceeded $173 billion in 1994, compared to annual average inflows of$34 billion during 1983–90 [World Bank (1995)]. Although the characteristics of capital inflows in this episode are different than in the period prior to the last debt crisis, nevertheless concerns about macroeconomic stability, loss in competitiveness, financial sector vulnerability and excessive borrowing remain the same. While the rise in inflows during 1991–93 was supported in part by low interest rates and weak economic activity in industrial countries, improved economic policies and prospects in most recipient countries also played an important role. The larger share in inflows of those countries that achieved greater progress in economic reforms, is evidence of the importance of recipient country policies. During this period, the composition of private flows to developing countries also became more diversified. Foreign direct investment (FDI) accounted for 45 percent of total equity inflows in 1994, with debt accounting for 32 percent and portfolio flows accounting for the remaining 23 percent

Zero-tillage Technology and Farm Profits: A Case Study of Wheat Growers in the Rice Zone of Punjab

The rice-wheat cropping zone of Punjab is the main producer of high-valued and fine quality basmati rice in Pakistan. The rice produced in this area is famous for its grain length and aromatic characteristics. Being an important export item, rice contributes significantly to the national foreign exchange earnings. Wheat is the other major crop of the rice-wheat system and being the staple food is central to national agricultural policies. Rice is grown on a vast area in this zone during Kharif mostly followed by wheat in the Rabi season. Studies have shown that a large gap exists between the potential and yields actually realised by the wheat growers of the area [Byerlee, et al. (1984); Hobbs (1985) and Sheikh, et al. (2000)]. Farmers’ practices regarding land preparation for paddy, wheat planting time, and other conflicts endogenous to the rice-wheat based cropping system were identified as the major factors limiting wheat yield in the area. The flooded and puddled soils that are well suited for paddy production as compared to well-drained conditions required for wheat is such an example of the system conflicts. The farmers in the rice-wheat zone of the Punjab predominantly grow basmati varieties, which are late maturing as compared to coarse varieties of rice. Therefore, paddy harvest is generally delayed at most of the farms in this zone. The late paddy harvest coupled with poor soil structure and loose plant residues create problems for preparation of a good seedbed and planting of wheat often gets late [Byerlee, et al. (1984)]. The farmers also had to resort to the broadcast method for wheat sowing which results in poor and patchy plant stands.

Evaluating Multicore Algorithms on the Unified Memory Model

One of the challenges to achieving good performance on multicore architectures is the effective utilization of the underlying memory hierarchy. While this is an issue for single-core architectures, it is a critical problem for multicore chips. In this paper, we formulate the unified multicore model (UMM) to help understand the fundamental limits on cache performance on these architectures. The UMM seamlessly handles different types of multiple-core processors with varying degrees of cache sharing at different levels. We demonstrate that our model can be used to study a variety of multicore architectures on a variety of applications. In particular, we use it to analyze an option pricing problem using the trinomial model and develop an algorithm for it that has near-optimal memory traffic between cache levels. We have implemented the algorithm on a two Quad-Core Intel Xeon 5310 1.6 GHz processors (8 cores). It achieves a peak performance of 19.5 GFLOPs, which is 38% of the theoretical peak of the multicore system. We demonstrate that our algorithm outperforms compiler-optimized and auto-parallelized code by a factor of up to 7.5

Identification of Natural Compounds as CTX-M-15 Inhibitors for the Management of Multidrug-Resistant Bacteria: An in-silico study

Background: Antibiotic resistance is a major global threat to the efficacy of bacterial infection treatment. Resistance to beta-lactam antibiotics in bacteria is primarily caused by the production of extended-spectrum-lactamases, with the CTX-M variant, particularly CTX-M-15, being the most common. The need for an effective CTX-M-15 inhibitor is currently pressing.Methods: This study screened a library of natural compounds from the ZINC database against the CTX-M-15 protein using the PyRx 0.8 tool. The SwissADME web platform was used to predict the ADMET properties of the five most promising compounds.Result: The identified hits compounds, ZINC1857626342, ZINC403692, ZINC408773, ZINC57926, and ZINC790938591 exhibited strong binding with CTX-M-15. These compounds interacted with crucial catalytic site residues in the CTX-M-15 protein, particularly Ser70 and Ser130. Notably, the binding energies of these compounds were higher than those of the reference compound avibactam. Furthermore, they exhibited pharmacologically favorable characteristics.Conclusion: These compounds show promise as potential CTX-M-15 inhibitors to combat bacterial resistance. However, more experimental research is needed to optimize these compounds for their role as CTX-M-15 inhibitors

Three-Dimensional Graph Drawing Procedures for Functions of Two and Several Variables

Many functions depend on more than one independent variable. For instance, the volume of a right circular cylinder is a function of its radius and its height, so it is a function V(r, h) of two variables r and h. Real valued functions of several independent real variables are defined similarly to functions in the single-variable case. In this article, we define functions of more than one independent variable and discuss ways to graph them. But their graph is impossible in the two-dimensional system and the MATLAB program is the language that guarantees computer implementation at a high level in mathematics, easily presenting calculations, images, graphs, and writing programs in its environment. For achieving this goal, we first explained the plot3 procedure in the three-dimensional coordinate system to draw the graph of two dependent subordinates on the MATLAB program environment, followed by the surf procedure as well as the mesh procedure. Then we explained the procedures mentioned in the polar coordinates. We have provided examples to better understand each procedure

Evaluating Multicore Algorithms on the Unified Memory Model

One of the challenges to achieving good performance on multicore architectures is the effective utilization of the underlying memory hierarchy. While this is an issue for single-core architectures, it is a critical problem for multicore chips. In this paper, we formulate the unified multicore model (UMM) to help understand the fundamental limits on cache performance on these architectures. The UMM seamlessly handles different types of multiple-core processors with varying degrees of cache sharing at different levels. We demonstrate that our model can be used to study a variety of multicore architectures on a variety of applications. In particular, we use it to analyze an option pricing problem using the trinomial model and develop an algorithm for it that has near-optimal memory traffic between cache levels. We have implemented the algorithm on a two Quad-Core Intel Xeon 5310 1.6 GHz processors (8 cores). It achieves a peak performance of 19.5 GFLOPs, which is 38% of the theoretical peak of the multicore system. We demonstrate that our algorithm outperforms compiler-optimized and auto-parallelized code by a factor of up to 7.5

INFLUENCE OF TEACHER FACTORS ON ACADEMIC PERFORMANCE IN UCE UNDER USE SCHOOLS IN YUMBE TOWN COUNCIL, YUMBE DISTRICT; A CROSS-SECTIONAL STUDY.

  Background: This study aims to find out the influence of Teacher factors on academic performance in UCE under USE schools in Yumbe town council, Yumbe District.  Methodology: A cross-sectional survey design based on qualitative and quantitative approaches was used to get the findings. The target population comprised of 121, head teachers, teachers, students, student leaders, district education officers, Board of governor members, and community leaders were randomly and purposively sampled. The methods of data collection included: a questionnaire survey, interview, observation, and documentary review. Descriptive and inferential statistical analyses were used and the data was presented using frequency tables and correlation matrices.  Results: The major findings were that: the majority (82%) of the teachers were well-trained and qualified, and most (62%) teachers were not well motivated by their stakeholders. Most (76%) teachers gave students ample time to practice/exercise and kept good records of their progress as shown by the 92% response rate. The teacher-student relationship was fairly good and most (54%) teachers were always present at school. Most (74% and 62%) teachers had positive attitudes towards their work and were adequately prepared before teaching.  Conclusion: The findings made the researcher conclude that teacher factors are very important in influencing academic performance in secondary schools in Yumbe town council, Yumbe district.  However, the teachers needed to be fully motivated more by the stakeholders in the form of good pay, improving working conditions, and their welfare among others if better academic performance was to be achieved in the USE schools in Yumbe town council, Yumbe district.  Recommendations: The Government of Uganda and school administrators should improve on the welfare of teachers in terms of pay, and decent accommodation if they are to be motivated to work hard towards better academic performance

Parallel spatial direct numerical simulations on the Intel iPSC/860 hypercube

The implementation and performance of a parallel spatial direct numerical simulation (PSDNS) approach on the Intel iPSC/860 hypercube is documented. The direct numerical simulation approach is used to compute spatially evolving disturbances associated with the laminar-to-turbulent transition in boundary-layer flows. The feasibility of using the PSDNS on the hypercube to perform transition studies is examined. The results indicate that the direct numerical simulation approach can effectively be parallelized on a distributed-memory parallel machine. By increasing the number of processors nearly ideal linear speedups are achieved with nonoptimized routines; slower than linear speedups are achieved with optimized (machine dependent library) routines. This slower than linear speedup results because the Fast Fourier Transform (FFT) routine dominates the computational cost and because the routine indicates less than ideal speedups. However with the machine-dependent routines the total computational cost decreases by a factor of 4 to 5 compared with standard FORTRAN routines. The computational cost increases linearly with spanwise wall-normal and streamwise grid refinements. The hypercube with 32 processors was estimated to require approximately twice the amount of Cray supercomputer single processor time to complete a comparable simulation; however it is estimated that a subgrid-scale model which reduces the required number of grid points and becomes a large-eddy simulation (PSLES) would reduce the computational cost and memory requirements by a factor of 10 over the PSDNS. This PSLES implementation would enable transition simulations on the hypercube at a reasonable computational cost