When is a bottleneck a bottleneck?

Bottlenecks, i.e. local reductions of capacity, are one of the most relevant scenarios of traffic systems. The asymmetric simple exclusion process (ASEP) with a defect is a minimal model for such a bottleneck scenario. One crucial question is "What is the critical strength of the defect that is required to create global effects, i.e. traffic jams localized at the defect position". Intuitively one would expect that already an arbitrarily small bottleneck strength leads to global effects in the system, e.g. a reduction of the maximal current. Therefore it came as a surprise when, based on computer simulations, it was claimed that the reaction of the system depends in non-continuous way on the defect strength and weak defects do not have a global influence on the system. Here we reconcile intuition and simulations by showing that indeed the critical defect strength is zero. We discuss the implications for the analysis of empirical and numerical data.Comment: 8 pages, to appear in the proceedings of Traffic and Granular Flow '1

Decentralized Resource Scheduling in Grid/Cloud Computing

In the Grid/Cloud environment, applications or services and resources belong to different organizations with different objectives. Entities in the Grid/Cloud are autonomous and self-interested; however, they are willing to share their resources and services to achieve their individual and collective goals. In such open environment, the scheduling decision is a challenge given the decentralized nature of the environment. Each entity has specific requirements and objectives that need to achieve. In this thesis, we review the Grid/Cloud computing technologies, environment characteristics and structure and indicate the challenges within the resource scheduling. We capture the Grid/Cloud scheduling model based on the complete requirement of the environment. We further create a mapping between the Grid/Cloud scheduling problem and the combinatorial allocation problem and propose an adequate economic-based optimization model based on the characteristic and the structure nature of the Grid/Cloud. By adequacy, we mean that a comprehensive view of required properties of the Grid/Cloud is captured. We utilize the captured properties and propose a bidding language that is expressive where entities have the ability to specify any set of preferences in the Grid/Cloud and simple as entities have the ability to express structured preferences directly. We propose a winner determination model and mechanism that utilizes the proposed bidding language and finds a scheduling solution. Our proposed approach integrates concepts and principles of mechanism design and classical scheduling theory. Furthermore, we argue that in such open environment privacy concerns by nature is part of the requirement in the Grid/Cloud. Hence, any scheduling decision within the Grid/Cloud computing environment is to incorporate the feasibility of privacy protection of an entity. Each entity has specific requirements in terms of scheduling and privacy preferences. We analyze the privacy problem in the Grid/Cloud computing environment and propose an economic based model and solution architecture that provides a scheduling solution given privacy concerns in the Grid/Cloud. Finally, as a demonstration of the applicability of the approach, we apply our solution by integrating with Globus toolkit (a well adopted tool to enable Grid/Cloud computing environment). We also, created simulation experimental results to capture the economic and time efficiency of the proposed solution

Mathematical models of eye movements

This is the author accepted manuscript. The final version is available from [the Institute of Mathematics and its ApplicationsSupported by the BBSRC grant no 36/MMI09774

Enhancement of Hoisting System Performance

In this paper it is required to enhance the performance of a mechanical system (here: a Hoisting System) where it is preferred to lift a different payloads with approximately the same speed of lifting and keeping at the same time the good performance, and this of course needs some intelligence of the system which will be responsible on measuring the present load and taking into account the speed and performance desired in order to achieve the requirements or the criteria. The process therefore is a Mechatronics System design which includes a measuring system, a control or automation technique, and an actuating system. The criteria built here in this research using a given Hoist system's characteristics and parameters and changing one of these parameters by the actuator depending on load value (i.e. making a calibration with which there will be a given value of the intentional parameter at which the speed and performance reach the requirements to any load value)

Studies on the antimicrobial effects of garlic (Allium sativum Linn), ginger (Zingiber officinale Roscoe) and lime (Citrus aurantifolia Linn)

The antimicrobial effect in vitro of aqueous and ethanolic extracts of garlic (Allium sativum Linn.), ginger (Zingiber officinale Roscoe) and lime (Citrus aurantifolia Linn.) juice were assayed against Staphylococcus aureus; Bacillus spp., Escherichia coli and Salmonella spp. All the test organisms were susceptible to undiluted lime-juice. The aqueous and ethanolic extracts of garlic and ginger singly did not inhibit any of the test organisms. The highest inhibition zone of 19 mm was observed with a combination of extracts on Staphylococcus aureus. Salmonella spp were resistant to almost all the extracts except lime. Key Words: Antimicrobial, ginger, garlic, lime, concoctions. African Journal of Biotechnology Vol.3(10) 2004: 552-55

Reconstruction of plasma density profiles by measuring spectra of radiation emitted from oscillating plasma dipoles

We suggest a new method for characterising non-uniform density distributions of plasma by measuring the spectra of radiation emitted from a localised plasma dipole oscillator excited by colliding electromagnetic pulses. The density distribution can be determined by scanning the collision point in space. Two-dimensional particle-in-cell simulations demonstrate the reconstruction of linear and nonlinear density profiles corresponding to laser-produced plasma. The method can be applied to a wide range of plasma, including fusion and low temperature plasmas. It overcomes many of the disadvantages of existing methods that only yield average densities along the path of probe pulses, such as interferometry and spectroscopy

Hedonic demand analysis for beef in Benin Metropolis

The study examined hedonic demand analysis for beef in Benin metropolis. To achieve this, the consumers’ implicit demand for beef within the framework of a hedonic analysis, and the implicit or shadow price of beef were examined. Primary data were used to generate information for the study and were collected with the use of a wellstructured questionnaire using the simple random sampling technique to obtain data from one hundred and seventy (170) respondents. Data collected were analysed using both descriptive and inferential statistics. The descriptive statistics used were frequency counts, mean, standard deviation and percentages, while the inferential statistics employed the correlation analysis and multiple regression analysis. The results of the descriptive statistics showed that more than half (54.1%) of the consumers were female household heads, who were married, in the age bracket of 40-59 years, of medium-size household family, and mainly civil servants within income bracket of N60000-79000. The results of the Hedonic analysis showed that, with an average unit price of N836.57 for beef, a consumer is strongly willing to pay additional N229.27 for beef with good taste, N227.10 for neat beef, N163.05 for beef of ‘proper’ processing style and N380.21 for fresh beef in the study area. Similarly, the consumer is willing to pay additionalN110.70 for beef which is properly packaged and N139.11 for beef  processed in a hygienic environment in the study area, though not with the same degree of willing as for taste, neatness and freshness. Thus a consumer will willingly pay about twice the normal price for a Kg of beef in the study area. However, other consumers who are keen on the modern processing style for beef production will pay an additional N163.05 per Kg which amounts to about N1700.00 per Kg of beef while others who possibly value modern processing style, in addition to well-packaged beef from a hygienic environment, will pay additional N249.81 per Kg which amounts to N1900.00 per Kg of beef.KEY WORDS: Hedonic, Verimax, Beef, Eigenvectors, Pric

Time-series analysis of Nigeria rice supply and demand: Error correction model approach

The study examined a time-series analysis of Nigeria rice supply and demand with a view to determining any long-run equilibrium between them using the Error Correction Model approach (ECM). The data used for the study represents the annual series of 1960-2007 (47 years) for rice supply and demand in Nigeria, derived from the World Rice Statistics compiled by the International Rice Research Institute (IRRI, 2009). The order of integration and the level of co-integration were determined using the Augmented Dickey Fuller (ADF), Johansen co-integration and Granger causality test. The result of the descriptive statistics showed that rice supply and demand had means of 1.8 and 1.6 million metric tonnes respectively with a demand-supply lag of 0.18 million metric tons. The Trace test indicated one co-integrating equation at the 0.05 level of significance while the Granger causality ran one-way from supply to demand. The result of the ECM shows that the co-efficient of the short-run and long-run relationships between rice demand and supply were 1.102963 and -0.043497 respectively. There is disequilibrium between Nigeria  rice supply and demand in the short-run but re-equilibrates at 0.043. Thus, the more the demand for rice, the higher the production is expected in order to avoid any shortage, in the short-run, which though will always even out in the long-run. Nigeria rice supply-demand exhibit disequilibrium in the short-run but has a long-run equilibrium.KEYWORDS: Rice, Integration, Co-integration, Unit-Root And Stationarity

The use of ultrasound-guided transversus abdominis plane blocks for total abdominal hysterectomy: A double-blind, controlled trial

Objectives: This study investigated the postoperative analgesic efficacy of bilateral ultrasound-guided transversus abdominis plane (TAP) blocks, in patients undergoing total abdominal hysterectomy.Design, setting and subjects: This was a prospective, randomised, double-blind, controlled study. Thirty patients were allocated to two groups; a TAP block group (n = 15) and a placebo group (n = 15). The TAP blocks were performed with 0.25% bupivacaine. The placebo group received sham blocks with normal saline, post induction of anaesthesia. Postoperatively,patients received patient-controlled intravenous morphine for analgesia.Outcome measures: The primary outcome was morphine consumption during the first 24 hours postoperatively. Secondary outcomes were  adequacy of pain relief, as assessed by pain scores at 0, 6 and 24 hours postoperatively, and side-effects.Results: Our study showed a significant between-group difference in morphine requirements (5.2 ± 3.9 vs. 9.7 ± 4.3 mg, p = 0.007, and 12.9 ± 8.9 mg vs. 25 ± 12.1 mg, p = 0.006) for the TAP group, compared with the placebo group at six and 24 hours, respectively. There were no significant between-group differences in pain scores. There were no complicationswith any of the blocks.Conclusion: Bilateral ultrasound-guided TAP blocks significantly reduced postoperative morphine consumption in a multimodal postoperative analgesia regimen for abdominal hysterectomy