The vendor location problem

Cataloged from PDF version of article.The vendor location problem is the problem of locating a given number of vendors and determining the number of vehicles and the service zones necessary for each vendor to achieve at least a given profit. We consider two versions of the problem with different objectives: maximizing the total profit and maximizing the demand covered. The demand and profit generated by a demand point are functions of the distance to the vendor. We propose integer programming models for both versions of the vendor location problem. We then prove that both are strongly NP-hard and we derive several families of valid inequalities to strengthen our formulations. We report the outcomes of a computational study where we investigate the effect of valid inequalities in reducing the duality gaps and the solution times for the vendor location problem

Feasibility of time-lapse seismic methodology for monitoring the injection of small quantities of CO2 into a saline formation, CO2CRC Otway Project

A key objective of Stage 2 of the CO2CRC Otway Project is to explore the ability of geophysical methods to detect and monitor injection of greenhouse gas into a saline formation. For this purpose, injection of some 10,000 30,000 tonnes of CO2-rich mixture into the Paaratte formation, a saline aquifer located at a depth of about 1,400 m, is planned. Before such an injection experiment is undertaken, we assess the feasibility of geophysical monitoring using computer modelling. To examine the detectability of the plume we need to estimate the time-lapse signal and time- lapse noise. The time lapse signal is modelled using flow simulations, fluid substitution and seismic forward modelling. In order to assess the applicability of time-lapse seismic to monitor the injection, the predicted signal is compared to the time-lapse noise level from the recent 4D seismic survey acquired at the Otway site in 2009-2010. The methodology is applied to two alternative reservoir intervals located at a depth of 1392-1399 m and 1445-1465 m below the sea level, respectively. These intervals are considered to be the two possible options for the injection. The results show that injection into the lower interval will produce a plume of a larger thickness and smaller lateral extent, and a seismic response that is more likely to be detectable. The developed feasibility assessment workflow, and the results of its application to the Otway site, can be used to assess the ability of seismic methods to detect and monitor greenhouse gas leakage in other CCS projects

Reservoir management through characterization of smart fields using capacitance-resistance models

Use of smart well technologies to improve the recovery has caught significant attention in the oil industry in the last decade. Capacitance-Resistance (CRM) methodology is a robust data-driven technique for reservoir surveillance. Reservoir sweep is a crucial part of efficient recovery, especially where significant investment is done by means of installation of smart wells that feature inflow control valves (ICVs) that are remotely controllable. However, as it is a relatively newer concept, effective use of this new technology has been a challenge. In this study, the objective is to present the efficient use of ICVs in intelligent fields through the integrated use of capacitance-resistance modeling and smart wells with ICVs. A standard realistic SPE reservoir simulation model of a waterflooding process is used in this study where the smart well ICVs are controlled with conditional statements called procedures in a fully commercial full-physics numerical reservoir simulator. The simulation data is utilized to build the CRM model to obtain the inter-well connectivities at the zonal level beyond only the inter-well connectivity data as smart wells provide control and information on the amount of injection into each layer or zone. Thus, after analyzing the CRM model to detect the inter-well connectivities at the zone/layer-level in an iterative way, the optimum injection not only at the well level but also at the perf/zone level is found. The workflow is outlined as well as the improvements in the results. The smart well technology has been challenged with the associated cost component thus, it is important to present the benefits of this technology with applications in more diverse cases with different workflows. It has been observed that a robust reservoir characterization in an intelligent field can provide an insight into the physics of reservoir including smart wells with ICVs. The results are presented in a comparative way against the base case to illustrate the incremental value of the use of ICVs along with key performance indicators. Most importantly, it has been shown that smart well use without a robust reservoir management strategy does not always lead to successful results. In reservoir management, it is not only important to catch the well level details but also see the big picture at the field level to improve the performance of the reservoirs beyond individual well performances taking into account the interference between wells. This method takes the reservoir surveillance to the next level where reservoir characterization is improved using smart field technologies and capacitance-resistance modeling as a robust cost-effective data-driven method

An alternative surgical approach to subclavian and innominate stenosis: a case series

We report three cases of symptomatic stenosis of the great vessels or supra-aortic trunks successfully treated surgically with aorto-subclavian and aorto-innominate bypass. Two were performed via manubriotomy and a third case via standard median sternotomy because of concomitant coronary revascularisation. There was complete symptomatic relief on follow-up, and radiological imaging confirmed good flow in the grafts and post-stenotic arteries

Label-free nanometer-resolution imaging of biological architectures through surface enhanced raman scattering

Label free imaging of the chemical environment of biological specimens would readily bridge the supramolecular and the cellular scales, if a chemical fingerprint technique such as Raman scattering can be coupled with super resolution imaging. We demonstrate the possibility of label-free super-resolution Raman imaging, by applying stochastic reconstruction to temporal fluctuations of the surface enhanced Raman scattering (SERS) signal which originate from biomolecular layers on large-area plasmonic surfaces with a high and uniform hot-spot density (>1011/cm2, 20 to 35 nm spacing). A resolution of 20 nm is demonstrated in reconstructed images of self-assembled peptide network and fibrilated lamellipodia of cardiomyocytes. Blink rate density is observed to be proportional to the excitation intensity and at high excitation densities (>10 kW/cm2) blinking is accompanied by molecular breakdown. However, at low powers, simultaneous Raman measurements show that SERS can provide sufficient blink rates required for image reconstruction without completely damaging the chemical structure

Label-Free Nanometer-Resolution Imaging of Biological Architectures through Surface Enhanced Raman Scattering

Label free imaging of the chemical environment of biological specimens would readily bridge the supramolecular and the cellular scales, if a chemical fingerprint technique such as Raman scattering can be coupled with super resolution imaging. We demonst

The impact of point mutations in the human androgen receptor : classification of mutations on the basis of transcriptional activity

Peer reviewedPublisher PD

Body mass index and dental caries in children and adolescents : a systematic review of literature published 2004 to 2011

The objectiveThe authors undertook an updated systematic review of the relationship between body mass index and dental caries in children and adolescents.MethodThe authors searched Medline, ISI, Cochrane, Scopus, Global Health and CINAHL databases and conducted lateral searches from reference lists for papers published from 2004 to 2011, inclusive. All empirical papers that tested associations between body mass index and dental caries in child and adolescent populations (aged 0 to 18 years) were included.ResultsDental caries is associated with both high and low body mass index.ConclusionA non-linear association between body mass index and dental caries may account for inconsistent findings in previous research. We recommend future research investigate the nature of the association between body mass index and dental caries in samples that include a full range of body mass index scores, and explore how factors such as socioeconomic status mediate the association between body mass index and dental caries.<br /

Inverse Relationship between PSA and IL-8 in Prostate Cancer: An Insight into a NF-κB-Mediated Mechanism

Background: Prostate specific antigen (PSA) is traditionally used as an indicator for the presence of prostate cancer (PCa) and radiotherapy is generally used to treat inoperable and locally advanced PCa. However, how cellular PSA level is associated with sensitivity of PCa to radiotherapy is unknown. The previous finding that the RelB-based NF-kB alternative pathway differentially regulates PSA and interleukin-8 (IL-8) in aggressive PCa has directed our attention to the role of RelB in the response of PCa to radiotherapy. Methodology/Principal Findings: RelB and its targets PSA and IL-8 in PCa cells were manipulated by ectopic expression in PCa cells with a low endogenous level of RelB (LNCaP) and by RNAi-based knock-down in PCa cells with a high constitutive level of RelB (PC3). The effects of RelB, PSA and IL-8 on the response of PCa to radiation treatment were examined in vitro and in xenograft tumors. RelB regulates PSA and IL-8 in an inverse manner. When the cellular levels of PSA and IL-8 were directly modulated by genetic manipulations or by the addition of recombinant proteins, the results demonstrate that upregulation of IL-8 enhanced radioresistance of PCa cells and concurrently down-regulated PSA. In contrast, up-regulation of PSA resulted in reduced radioresistance with concurrent down-regulation of IL-8. Conclusion/Significance: RelB plays a critical role in the response of PCa to radiotherapy and the inverse expression of IL-8 and PSA. The results identify a previously unrecognized relationship between IL-8 and PSA in the response of PCa cells t