Chemistry and Biology of Streptogramin A Antibiotics

The streptogramin A antibiotics have proven to be highly active against Gram positive bacteria, particularly methicillin-resistant Staphylococcus aureus. Members of this group of compounds are characterized by a 23-membered macrocycles containing polyene, oxazole, amide and ester functionality. The chemistry and biology of these valuable antimicrobial agents is covered

Sample Size Calculation Guide - Part 3: How to Calculate the Sample Size for an Independent Case-control Study

In the previous educational articles, we explained how to calculate the sample size for a rate or a single proportion and how to calculate the sample size for an independent cohort study. In this article, we will explain how to calculate the sample size for an independent case-control study based on the odds ratios or two proportions representing the exposure rates in the case and the control groups

Sample Size Calculation Guide - Part 3: How to Calculate the Sample Size for an Independent Case-control Study

In the previous educational articles, we explained how to calculate the sample size for a rate or a single proportion and how to calculate the sample size for an independent cohort study. In this article, we will explain how to calculate the sample size for an independent case-control study based on the odds ratios or two proportions representing the exposure rates in the case and the control groups

Using structured analysis and design technique (SADT) for simulation conceptual modelling

Conceptual Modelling (CM) has received little attention in the area of Modelling and Simulation (M&S) and more specifically in Discrete Event Simulation (DES). It is widely agreed that CM is least understood despite its importance. This is however, not the case in other fields of science and engineering (especially, computer science, systems engineering and software engineering). In Computer Science (CS) alone, CM has been extensively used for requirements specification and some well-established methods are in practice. The aim of the thesis is to propose a CM framework based on the principles of software engineering and CS. The development of the framework is adapted from a well-known software engineering method called Structured Analysis and Design Technique (SADT), hence it is called SADT CM. It is argued that by adapting approaches from CS, similar benefits can be achieved in terms of formality, understanding, communication and quality. A comprehensive cross-disciplinary review of CM in CS and M&S is undertaken, which highlights the dearth of standards within M&S CM when compared to CS. Three important sub-fields of CS are considered for this purpose namely, information systems, databases and software engineering. The review identifies two potential methods that could be adopted for developing a M&S CM framework. The first method called PREView was found unsuitable for M&S CM in DES domain. Hence, the thesis concentrates on developing the framework based on SADT. The SADT CM framework is evaluated on three-in depth test cases that investigate the feasibility of the approach. The study also contributes to the literature by conducting a usability test of the CM framework in an experimental setting. A comprehensive user-guide has also been developed as part of the research for users to follow the framewor

Low-level jet height’s impact on wind turbine loads: A case study

Over the years, wind turbines have been steadily increasing in size, with newer models boasting larger dimensions. For instance, the diameter of an installed prototype offshore wind turbine in late 2022 was over 200 m, which is significantly larger than in 2010, where the average size was 90 m. This results in new interactions between the wind turbine and the atmosphere in the form of Low-Level Jets (LLJs). The thesis aims to study the effect of a LLJ on the wind-induced response of a 15 MW offshore wind turbine. Engineering tools, i.e. TurbSim and OpenFAST, were used to simulate the turbulence boxes and the load response of a large offshore floating turbine. The results showed that the interaction between the LLJ profiles and the wind turbine response is not trivial, and the development of the loads as the LLJ height increases can’t be described by one single pattern. They were however closely related to the aerodynamic loads.Masteroppgave i energiENERGI399MAMN-ENER

Pedestrian Injury Severity Analysis in Motor Vehicle Crashes in Ohio

According to the National Highway Traffic Safety Administration, 116 pedestrians were killed in motor vehicle crashes in Ohio in 2015. However, no study to date has analyzed crashes in Ohio in order to explore the factors contributing to the pedestrian injury severity resulting from motor vehicle crashes. This study fills this gap by investigating the crashes involving pedestrians exclusively in Ohio. This study uses the crash data from the Highway Safety Information System, from 2009 to 2013. The explanatory factors include the pedestrian, driver, vehicle, crash, and roadway characteristics. Both fixed- and random-parameters ordered probit models of injury severity (where possible outcomes are major, minor, and possible/no injury) were estimated. The model results indicate that older pedestrian (65 and over), younger driver (less than 24), driving under influence (DUI), struck by truck, dark-unlighted roadways, six-lane roadways, and speed limits of 40 mph and 50 mph were all factors associated with more severe injuries to the pedestrians. Conversely, older driver (65 and over), passenger car, crash occurring in urban locations, daytime traffic off-peak (10 a.m. to 3:59 p.m.), weekdays, and daylight condition were all factors associated with less severe injuries. This study provides specific safety recommendations so that effective countermeasures can be developed and implemented by policy makers, which in turn will improve overall highway safety

The Suitability of Bailey Method for Design of Local Asphalt Concrete Mixture

The study investigated the behaviour of asphalt concrete mixes for aggregate gradations, according to the Iraqi specification using the Bailey method designed by an Excel spreadsheet. In mixing aggregates with varying gradations (coarse and fine aggregate), The Bailey method is a systematic methodology that offers aggregate interlocking as the backbone of the framework and a controlled gradation to complete the blends. Six types of gradation are used according to the bailey method considered in this study. Two-course prepared Asphalt Concrete Wearing and Asphalt Concrete binder, the Nominal Maximum Aggregate Sizes (NMAS) of the mixtures are 19 and 12.5 mm, respectively. The total number of specimens was 240 for both layers (15 samples) for each Chosen Unit Weight (CUW). The Marshall Test results show the increase in stability and decrease in flow and bulk density when the rise in CUW for both courses. In volumetric properties, VMA increases when the increase in CUW. When an increase in CUW air void increases gradually. The permanent deformation for the coarse aggregate (95, 100, 105% CUW) has more resistances than the fine aggregate (80, 85, 90%) wearing and binder coarse. The CUW (105%) blend of wearing, and binder course has a high value of stability and resistance to permanent deformation (11.9, 11.1 kN). The CUW above mentioned is considered a good design aggregate structure and produces improvement to the Marshall properties, leading to better performance for pavement roads and higher resistance to distresses. Doi: 10.28991/cej-2021-03091693 Full Text: PD