Operation of the ATLAS detector with first collisions at 7 TeV at the LHC

The ATLAS experiment has successfully recorded over 300 nb^-1 of pp collisions at 7 TeV provided by the Large Hadron Collider, with an efficiency of 94%. We describe the data acquisition, trigger, reconstruction, calibration, monitoring, and luminosity measurement infrastructure that have made this possible.Comment: 6 pages, 3 figures. Proceedings of the 35th International Conference of High Energy Physics, July 22-28, 2010, Paris, Franc

Impact of Rare Decays t→ℓ′νbℓℓt \to \ell' \nu b \ell\ell and t→qq′bℓℓt \to q q' b \ell\ell on Searches for Top-Associated Physics

Searches for top quark-associated physics such as $t\bar t W$ or $t\bar t H$ in final states with multiple leptons require a careful accounting of expected backgrounds due to the lack of reconstructible resonances. We demonstrate that the rare top quark decays $t \to \ell' \nu b \ell\ell$ and $t \to q q' b \ell\ell$, when a soft lepton is not detected, can contribute a non-negligible background to such searches. Simulations in the LHC experiments typically do not account for such decays and as such backgrounds to such searches may be underestimated.Comment: 13 pages, 6 figure

Comparing Point Cloud Strategies for Collider Event Classification

In this paper, we compare several event classification architectures defined on the point cloud representation of collider events. These approaches, which are based on the frameworks of deep sets and edge convolutions, circumvent many of the difficulties associated with traditional feature engineering. To benchmark our architectures against more traditional event classification strategies, we perform a case study involving Higgs boson decays to tau leptons. We find a 2.5 times increase in performance compared to a baseline ATLAS analysis with engineered features. Our point cloud architectures can be viewed as simplified versions of graph neural networks, where each particle in the event corresponds to a graph node. In our case study, we find the best balance of performance and computational cost for simple pairwise architectures, which are based on learned edge features.Comment: 19 pages, 7 figures, 3 tables, code available at https://github.com/DelonShen/classifying-collider-events-with-point-clouds; v2: to match published versio

Powers of the Executive and Legislature in Budget Making Process in Nigeria: An Overview

Friction between the executive and legislative arms of the government is a common phenomenon in modern democracies the world over. Because of its attendant consequences, the budget process is often a cause of significant friction between the legislature and executive arms. In Nigeria, the issue that calls for determination has been the extent of powers of the legislature in matters of budget formulation and approval. For years, this dispute has remained unabated and none of the parties has summoned the courage to approach the courts for its interpretation. This controversy, once again, has been in the front burner, resulting in inordinate delay in the passage of the 2016 nation’s Budget. The executive arm of the government is vehement in objecting to any amendments, modifications and alterations made to the annual budgetary estimates prepared by the executive and placed before the National Assembly as it affects various ministries and government departments. In other words, it is their take that the function of the legislative arm is simply to ‘rubber stamp’ the budget estimates. Politicians, legislators and lawyers are divided on this issue. This paper examines the powers and functions of both arms of government but more especially the legislature on Appropriation Bills. We examined a critical aspect of the controversy that surrounded the delay in the passage of the 2016 Budget because of the importance it has for future budgetary processes. We argue in this article that in the interest of allowing inputs of trade unions, NGOs and other stakeholders through the opportunities provided by Public Hearings, it is in the larger public interest to sustain the operation of the current legal framework which supports, in our humble opinion, the power of the National Assembly to alter the budgetary estimates submitted by the executive, either marginally or fundamentally, as the National Assembly may deem fit.  We support our argument with an overview of international practices, which vary, depending only on constitutional or legal provisions in individual countries. A brief discussion on the relationship which exists in both arms of government, the causes and effect of frictions between them are also considered. Keywords: conflicts, executive arm, legislative arm, powers, budgetary estimates, appropriation bills

Mixture Density Network Estimation of Continuous Variable Maximum Likelihood Using Discrete Training Samples

Mixture Density Networks (MDNs) can be used to generate probability density functions of model parameters $\boldsymbol{\theta}$ given a set of observables $\mathbf{x}$. In some applications, training data are available only for discrete values of a continuous parameter $\boldsymbol{\theta}$. In such situations a number of performance-limiting issues arise which can result in biased estimates. We demonstrate the usage of MDNs for parameter estimation, discuss the origins of the biases, and propose a corrective method for each issue

How Organizational Culture as an Enabler of Knowledge Management Systems Influence Sustainable Competitive Advantage amongst Humanitarian Agencies in Kenya

This study investigated the influence of Knowledge Management (KM) systems on Sustainable Competitive Advantage (SCA) amongst Humanitarian Agencies-HAs through the use of organizational culture as an enabler of knowledge management. The objective of study was to show how organizational culture affects sustainable competitive advantage in humanitarian agencies- HAs- in Kenya. The study population was 42 HAs with 10,487 employees in Kenya. Both the primary and secondary data were collected using questionnaires, interviews, and observation checklists. The questionnaires were administered by a drop and collect method to ensure high response rates. Employees were stratified into management and junior staff. Purposive sampling was then used to sample management staff in the agencies surveyed and simple random sampling techniques were used to sample employees at the junior level. Statistical tools such as cross-tabulation and frequency tables were used to analyze the data. This study adopted a descriptive research design. The study used resource-based theory of knowledge management for competitive advantage as its theoretical basis. The resource-based view and theory of the firm defines a strategic asset as one that is rare, valuable, imperfectly imitable and non-substitutable. Knowledge is seen as one such strategic asset with the potential to be a source of competitive advantage for an organization. By adopting a resource-based theory of the firm with an extension of a knowledge-based perspective, this study aimed at developing and validating a conceptual model of the relationships between knowledge management enablers and their influence on competitive advantage amongst humanitarian agencies in Kenya. From the study, there is substantial evidence to show that knowledge management has a strong positive influence on sustainable competitive advantage. The results from the 42 agencies surveyed reconfirmed a general agreement found in the literature that culture makes a unique and significant contribution to the sustainable competitive advantage of humanitarian agencies. Finally, recommendations were offered from practical ideas, drawn from experience, and intended for practitioners working with HAs but are also based on the theory behind the knowledge management concept and are just as relevant for consideration by knowledge management and development theorists alike. Key Words: Knowledge Management, Competitive Advantage, Humanitarian agencies, Culture, Strategy, Organization, Enabler

Knowledge Management Systems That Influence Sustainable Competitive Advantage amongst Humanitarian Agencies in Kenya- Case of Information Technology Systems as an Enabler of Knowledge Management

This study investigated the influence of Knowledge Management (KM) systems on Sustainable Competitive Advantage (SCA) amongst Humanitarian Agencies-HAs through the use of IT systems as an enabler of knowledge management. The objective of study was to examine how information technology systems affect sustainable competitive advantage in humanitarian agencies- HAs- in Kenya. The study population was 42 HAs with 10,487 employees in Kenya. Both the primary and secondary data were collected using questionnaires, interviews, and observation checklists. The questionnaires were administered by a drop and collect method to ensure high response rates. Employees were stratified into management and junior staff. Purposive sampling was then used to sample management staff in the agencies surveyed and simple random sampling techniques were used to sample employees at the junior level. Statistical tools such as cross-tabulation and frequency tables were used to analyze the data. This study adopted a descriptive research design. The study used resource-based theory of knowledge management for competitive advantage as its theoretical basis. The resource-based view and theory of the firm defines a strategic asset as one that is rare, valuable, imperfectly imitable and non-substitutable. Knowledge is seen as one such strategic asset with the potential to be a source of competitive advantage for an organization. By adopting a resource-based theory of the firm with an extension of a knowledge-based perspective, this study aimed at developing and validating a conceptual model of the relationships between knowledge management enabler- it Systems and their influence on competitive advantage amongst humanitarian agencies in Kenya. From the study, there is substantial evidence to show that knowledge management has a strong positive influence on sustainable competitive advantage. The results from the 42 agencies surveyed reconfirmed a general agreement found in the literature that technological systems are ideal to bring significant positive correlations in improving organizational competitive advantage. Finally, recommendations were offered from practical ideas, drawn from experience, and intended for practitioners working with HAs but are also based on the theory behind the knowledge management concept and are just as relevant for consideration by knowledge management and development theorists alike. Key Words: Knowledge Management, Competitive Advantage, Humanitarian agencies, Civic, IT, Strategy, Organization, Enabler

The differential influence of HIV-1 subtype C,nucleoside analog resistance mutations: K65R, A62V, S68N and Y115F susceptibility to tenofovir.

Masters Degree. University of KwaZulu-Natal, Durban.The use of Tenofovir Disoproxil Fumerate (TDF) for the treatment of HIV-1 infection has been recommended for the first-line as well as a second-line antiretroviral regimen in South Africa, due to its high antiretroviral activity and low toxicity level. However, the efficacy of the drug could be threatened by the emergence of drug resistance mutations. The development of TDF resistance poses a public health threat. TDF resistance can be acquired through a selection of the K65R mutation or the K70E mutation (though less frequently) under TDF selection pressure. Besides, K65R and K70E mutations, recent studies have identified other mutations associated with TDF resistance such as A62V, K65N, S68G/N/D, K70E/Q/T, L74I, V75L, and Y115F. These mutations were particularly observed to be in association with the K65R mutation and were reported to be more common in HIV-1 subtype C viruses. Also, these mutations could cause high-level resistance to TDF, especially when in combination with K65R. However, in-vitro studies are required to demonstrate their influence on viral fitness and TDF susceptibility. In this study, we investigated the impact of K65R, A62V, S68D, Y115F, and K65R+S68N on replication capacity and TDF susceptibility. The reverse transcriptase (RT) region was amplified from a drug-naive HIV-1 subtype C isolate obtained from a patient enrolled in the Tropism study (BREC: BF088/07) and cloned into a TOPO vector using a TOPO TA cloning kit. The HIV-1 RT mutations (K65R, A62V, S68D, Y115F, K65R+A62V, K65R+S68D, K65R+S68G, K65R+S68N, and K65R+Y115F) were introduced into the TOPO+RTsubC recombinant using the Quikchange lightning Multi site-directed mutagenesis kit. Next, recombinant viruses were created by co-transfection of the mutant RT amplicons and a pNL4-3-deleted-reverse transcriptase (RT) (pNL43ΔRT) backbone into GXR cells by electroporation. The replication capacity of the mutant viruses was assessed using a replication method that utilized a green fluorescent protein (GFP) reporter cell line and flow cytometry. We evaluated the replication capacity using the exponential growth curve function in Excel to determine the percentage GFP-expressing cells between days 2 and 6. The impact of the mutant viruses on susceptibility to TDF was performed in a luciferase-based assay. The 50% inhibitory concentration (IC50) was calculated using Graph Pad Prism. Drug susceptibility was expressed as the fold change in IC50 of mutant virus compared with the wild type virus. Of the 5 TDF- selected mutants analysed: A62V, K65R, and Y115F mutants display a reduction in replicative fitness whereas, S68D and K65R+S68N showed high viral fitness. Interestingly, the TDF- selected resistance mutations we analysed, showed high susceptibility (A62V, S68D, and Y115F) and reduced susceptibility (K65R and K65R+S68N) to TDF. Our findings support the hypothesis that TDF- selected mutations only confer reduced susceptibility to TDF. Hence, further study is needed on various combinations of TDF-selected resistance mutations to further solidify this claim.Ethical Approval for thesis is on page iv