Comparative study of two needle models in terms of deflection during inferior alveolar nerve block

Objectives: The purpose of this study is to determine the possible differences in deflection between two needles of same length and external gauge but with different internal gauges during truncal block of the inferior alveolar nerve. The initial working hypothesis was that greater deflection may be expected with larger internal gauge needles. Study design: Four clinicians subjected 346 patients to inferior alveolar nerve block and infiltrating anesthesia of the buccal nerve trajectory for the surgical or conventional extraction of the lower third molar. A nonautoaspirating syringe system with 2 types of needle was used: a standard 27-gauge x 35-mm needle with an internal gauge of 0.215 mm or an XL Monoprotect® 27-gauge x 35-mm needle with an internal gauge of 0.265 mm. The following information was systematically recorded for each patient: needle type, gender, anesthetic technique (direct or indirect truncal block) and the number of bone contacts during the procedure, the patient-extraction side, the practitioner performing the technique, and blood aspiration (either positive or negative). Results: 346 needles were used in total. 190 were standard needles (27-gauge x 35-mm needle with an internal gauge of 0.215 mm) and 156 were XL Monoprotect®. Incidence of deflection was observed in 49.1% of cases (170 needles) where 94 were standard needles and 76 XL Monoprotect®. Needle torsion ranged from 0º and 6º. Conclusions: No significant differences were recorded in terms of deflection and internal gauge, operator, patient-extraction side, the anesthetic technique involved and the number of bone contacts during the procedure

Towards Inter-organizational Working Capital Management

Working capital is an investment which is tied up into the inventories and accounts receivable and which is released with accounts payable. Due to the current business landscape with tightened financial conditions and finance markets, organizations emphasize efficient working capital management. With efficient working capital management, a company can reduce the need of finance, free up cash, increase profitability, improve liquidity, increase the efficiency of operations, and decrease (financing) costs. From the perspective of an individual company, efficient working capital management means decreasing inventory levels by shortening the cycle time of inventories, decreasing accounts receivable by shortening the trade credit terms and effective collection procedures, and increasing the level of accounts payable by paying the suppliers later. From an inter-organizational perspective, however, working capital should not be sub-optimized by a single company but holistic view to working capital management through the supply chain should be adopted to create value and improve performance together. The purpose of this research is to take academic research as well as practical management towards inter-organizational working capital management. The thesis discusses the benefits as well as mechanisms of working capital management in the inter-organizational context and has two main objectives: (1) to examine the effect of inter-organizational working capital management on performance in the value chain context and (2) to develop models of working capital management for internal as well as inter-organizational value chains. The results of the archival research conducted in the value chain of the pulp and paper industry and the value chain of the automotive industry indicate that companies can increase relative profitability by managing working capital comprehensively by taking into account all three components, and holistically though the value chain. Companies in the value chain benefit from different strategies in working capital management depending on the position of the company in the value chain. This can be taken into account in inter-organizational working capital management. The effects of inter-organizational working capital management actions on the financing costs of working capital were studied via simulations. Simulations also show that the value chain and individual companies benefit from an inter-organizational view to working capital management. Inter-organizational working capital management actions include for example: shortening the cycle time of inventories, reducing product costs, shifting inventories, shortening payment terms, and considering the cost of capital. The thesis also provides solutions for the practical requirements for tools to control working capital. The design science part of the research introduces the adjusted cash conversion cycle (ACCC) model for internal value chains, as well as models for working capital management in the inter-organizational value chain context: the working capital management model (WCMM) and the financial cycle time model (FCTM) designed in corporation and product levels respectively. This research contributes to literature on working capital management and interorganizational accounting. The research gives a holistic, inter-organizational view to the management of working capital. It advances the knowledge in working capital management on operational level, increases knowledge in the recently risen theme of supply chainoriented, collaborative working capital management, combines management accounting research with supply chain management research, and contributes to the demand of practical inter-organizational accounting methods. In addition, the research has strong practical focus as new managerial methods are introduced.

Queueing Models with Vacations and Working Vacations

The thesis entitled “Queueing Models with Vacations and Working Vacations" consists of seven chapters including the introductory chapter. In chapters 2 to 7 we analyze different queueing models highlighting the role played by vacations and working vacations. The duration of vacation is exponentially distributed in all these models and multiple vacation policy is followed.In chapter 2 we discuss an M/M/2 queueing system with heterogeneous servers, one of which is always available while the other goes on vacation in the absence of customers waiting for service. Conditional stochastic decomposition of queue length is derived. An illustrative example is provided to study the effect of the input parameters on the system performance measures. Chapter 3 considers a similar setup as chapter 2. The model is analyzed in essentially the same way as in chapter 2 and a numerical example is provided to bring out the qualitative nature of the model. The MAP is a tractable class of point process which is in general nonrenewal. In spite of its versatility it is highly tractable as well. Phase type distributions are ideally suited for applying matrix analytic methods. In all the remaining chapters we assume the arrival process to be MAP and service process to be phase type. In chapter 4 we consider a MAP/PH/1 queue with working vacations. At a departure epoch, the server finding the system empty, takes a vacation. A customer arriving during a vacation will be served but at a lower rate.Chapter 5 discusses a MAP/PH/1 retrial queueing system with working vacations.In chapter 6 the setup of the model is similar to that of chapter 5. The signicant dierence in this model is that there is a nite buer for arrivals.Chapter 7 considers an MMAP(2)/PH/1 queueing model with a nite retrial group

Queueing Models with Vacations and Working Vacations

The objective of the study of \Queueing models with vacations and working vacations" was two fold; to minimize the server idle time and improve the e ciency of the service system. Keeping this in mind we considered queueing models in di erent set up in this thesis. Chapter 1 introduced the concepts and techniques used in the thesis and also provided a summary of the work done. In chapter 2 we considered an M=M=2 queueing model, where one of the two heterogeneous servers takes multiple vacations. We studied the performance of the system with the help of busy period analysis and computation of mean waiting time of a customer in the stationary regime. Conditional stochastic decomposition of queue length was derived. To improve the e ciency of this system we came up with a modi ed model in chapter 3. In this model the vacationing server attends the customers, during vacation at a slower service rate. Chapter 4 analyzed a working vacation queueing model in a more general set up. The introduction of N policy makes this MAP=PH=1 model di erent from all working vacation models available in the literature. A detailed analysis of performance of the model was provided with the help of computation of measures such as mean waiting time of a customer who gets service in normal mode and vacation mode.

Shale Gas and the EU Internal Gas Market: Beyond the Hype and Hysteria. CEPS Working Document No. 369, September 2012

This paper analyses the interplay between shale gas and the EU internal gas market. Drawing on data presented in the 2012 International Energy Agency’s report on unconventional gas and additional scenario analyses performed by the Joint Research Centre, the paper is based on the assumption that shale gas will not fundamentally change the EU’s dependence on foreign gas supplies. It argues that attention should be shifted away from hyping shale gas to completing the internal gas market. Two main reasons are given for this. First, the internal gas market is needed to enable shale gas development in countries where there is political support for shale gas extraction. And second, a well-functioning internal gas market would, arguably, contribute much more to Europe’s security of supply than domestic shale gas exploitation. This has important implications for the shale gas industry. As it is hard to see how subsidies or exemptions from environmental legislation could be justified, shale gas development in Europe will only go ahead if it proves to be both economically and environmentally viable. It is thus up to the energy industry to demonstrate that this is the case.