Tight Margins Research Articles

Unconventional monetary policy expansion: the economic impact through a dynamic CGE model

The ongoing economic stagnation and low inflation rates affecting EU have refuelled the debate on the role and the limits of monetary policy in pushing the economic growth. Given the tight margins for fiscal policy for EU state members, traditional and unconventional monetary policies are becoming more looked-for to break out of this condition. However, the main issue on whether the real or nominal aspects prevails still remains. In this situation, a framework able to identify and analyse any interaction between economic and financial flows becomes crucial to detect the dynamics pushing towards expansions or contractions resulting from monetary policies. Therefore, the aim of this paper is to investigate the direct and indirect impact of monetary policies implemented by the European Central Bank on the main Italian macroeconomic variables both in aggregate and disaggregate terms. For this purpose we use dynamic computable general equilibrium (CGE) model calibrated on the financial social accounting matrix for Italian economy.

Unconventional monetary policy expansion: the economic impact through a dynamic CGE model

The ongoing economic stagnation and low inflation rates affecting EU have refuelled the debate on the role and the limits of monetary policy in pushing the economic growth. Given the tight margins for fiscal policy for EU state members, traditional and unconventional monetary policies are becoming more looked-for to break out of this condition. However, the main issue on whether the real or nominal aspects prevails still remains. In this situation, a framework able to identify and analyse any interaction between economic and financial flows becomes crucial to detect the dynamics pushing towards expansions or contractions resulting from monetary policies. Therefore, the aim of this paper is to investigate the direct and indirect impact of monetary policies implemented by the European Central Bank on the main Italian macroeconomic variables both in aggregate and disaggregate terms. For this purpose we use dynamic computable general equilibrium (CGE) model calibrated on the financial social accounting matrix for Italian economy.

Interest Rate Swaps Clearing and Systemic Risk

We develop a model to analyze distress spillover from the OTC interest rate swaps (IRS) market into the interbank market due to central clearing and margin requirements. We show that margin procyclicality in the OTC IRS market derived by interest rate volatility can lead to the onset of systemic liquidity shortage in the interbank market. We also show that central clearing may increase systemic liquidity risk due to tight margin requirements.

To prep or not to prep - that is the question: A randomized trial on the use of antiflatulent medication as part of bowel preparation for patients having image guided external beam radiation therapy to the prostate

IntroductionRadiation therapy is a standard treatment option for prostate cancer. With growing use of escalated doses and tighter margins, procedures to limit rectal size variation are needed to reduce prostate motion, increase treatment accuracy, and minimize rectal toxicity. This prospective study was done to determine whether the introduction of an antiflatulent medication would decrease rectal distention at computed tomography (CT) simulation and throughout a course of radiation therapy. Methods and materialsPatients undergoing a radical course of radiation therapy to the prostate/prostate bed were eligible to participate. Participants were randomly assigned to the intervention arm (antiflatulent medication) or the control arm (no medication). For each participant, the number of CT simulation rescans was recorded. Rectal diameters were measured on CT simulation and treatment cone beam CT scans. Acute rectal toxicities were assessed at baseline and weekly using National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE), version 4.0. A χ2 analysis was used to compare the number of participants requiring a rescan in each study arm. Change in rectal diameter over time was assessed using repeated measures analysis of variance. ResultsA total of 78 patients participated, with equal numbers assigned to each study arm. There was no significant difference between arms in the number of participants requiring a CT simulation rescan (P = .5551). There was no significant variation in rectal diameter between arms (P = .8999); however, there was a significant effect of time (P = .0017) and a significant interaction effect between study arm and time on rectal diameter (P = .0141). No acute rectal toxicities above grade 2 were reported. ConclusionsThe addition of antiflatulent medication did not affect the frequency of CT simulation rescans. Both time and the interaction between study arm and time had a statistically significant effect on rectal diameter, although neither finding was clinically significant. Instead, standardized bowel preparation education developed for this study may have been sufficient to limit rectal size variation.

Aquaponics Automation – Design Techniques

Aquaponics operators that have transitioned from hobby to commercial operators have commonly failed to meet commercial expectations. One of the reasons for failures is the occurrence of severe technical errors. Unexpected events can often have drastic financial consequences on new operators, which could be initially operating within tight margins. Standard techniques like Hazard and Operability studies (HAZOP) are conducted by process and chemical industries to do systematic analysis on a process and its sub-systems. Many aquaponics operators are not familiar with these design processes and find design inadequacies after an event, which normally has financial consequences. This design process is able to identify disturbances that could lead to product deviation and identify hazards that could affect the environment. Identifying process issues and designing engineering controls to prevent or mitigate issues can be carried out in multiple forms or design tools. Failure Mode Effect Analysis (FMEA) is one such tool in a designer’s toolbox and is recognized as an international standard (IEC 60812), which describes techniques to analyze processes that can effect the reliability of a process plant or determine what possible hazards could be present. The use of FMEA has been utilized by industries to aid in carrying out HAZOP design processes, the use of these design processes can lead to inherently reliable processes. Piping and Instrumentation Diagrams also referred to as Process and Instrumentation Diagram (P&ID) are used in the process industry to show an overview of the process plant. The P&ID also identifies instruments that could be required for measurement and any associated alarms that are present to warn operators and mitigate failures in the process. The use of these design tools have identified and mitigated the risks within the initial design concept to prevent these technical errors with engineering controls designed into the process.

Effect of PTV and Collimator Margins on Tumor Control for Patients with Stage III Non-small Cell Lung Cancer in NRG Oncology RTOG-0617

RTOG-0617, a randomized phase III cooperative group trial using 2 x 2 factorial design, with radiation dose as one factor and cetuximab as the other factor for locally advanced non-small cell lung cancer, reported that patients in the high dose arms (74-Gy) had poorer survival and local control than those in the low dose arms (60-Gy). We hypothesized that patients in the 74-Gy arm have tighter planning target volume (PTV) and collimator margins, which may have caused poorer local control due to marginal misses. A total of 461 eligible patients were included in this study, with 261 and 200 patients in the 60-Gy and 74-Gy groups respectively. Local tumor control was defined as local progression free survival (LPFS). To study the PTV margin effect, a standard PTV was generated by expanding the gross tumor volume (GTV) with a 10 mm margin. A margin deviation index (MDI) was calculated as the percentage change of equivalent uniform dose (EUD) between the original PTV and the new PTV. Similarly, another new PTV was generated by expanding the original PTV with 6 mm margin, and a dose gradient index (DGI) was calculated as the percentage change of EUD between the original PTV and the new PTV to study the effect of collimator margin. A Cox statistical model was used to determine the associations of MDI and DGI with LPFS. MDI was 1.1 ± 1.6 and 1.5 ± 1.7 for the 60-Gy and 74-Gy groups, respectively (T test: P > 0.05), and DGI was 5.8 ± 4.4 and 6.7 ± 4.3 correspondingly (P > 0.05). The number of patients with extremely tight MDI (>3) or DGI (>11) was 27/261 (10%) and 26/200 (13%), or 30/261 (11%), 26/200 (13%) for the 60-Gy and 74-Gy group, respectively (P > 0.05). Interestingly, a larger DGI (tighter collimator margin) showed significantly better LPFS (HR = 0.98, P = 0.04), and a larger MDI (tighter PTV margin) had a trend of better LPFS (HR = 0.95, P = 0.10) for the entire group of patients. Larger MDI and DGI tended to result in better local control, suggesting that deviation from the standard PTV margin or tight collimator margin was not the cause of unexpected result in RTOG-0617. Further studies are required to better understand this phenomenon.

Embedding Automatic Risk-Level Estimation and Performance Analysis in Drilling Plans

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 181018, “Automatic Performance Analysis and Estimation of Risk Level Embedded in Drilling-Operation Plans,” by Eric Cayeux, SPE, and Benoît Daireaux, SPE, IRIS; Mohsen Karimi Balov, Statoil; Stein Haavardstein, ConocoPhillips; Leif Magne Stokland, Wintershall; and Arild Saasen, SPE, Det Norske, prepared for the 2016 SPE Intelligent Energy International Conference and Exhibition, Aberdeen, 6–8 September. The paper has not been peer reviewed. It is not unusual that the difficulties encountered during a drilling operation can be tracked to choices made during planning. However, generating a robust drilling-operation plan is not easy because substantial uncertainties are often associated with the actual geological context. To address this problem, this paper presents a method that quantitatively evaluates the risk levels of a drilling-operation plan as a function of the underlying uncertainty associated with its description. Introduction A drilling operation is always subject to operational risks (e.g., formation-fluid influx, lost circulation, borehole instability, packoff, stuck pipe, or drillstring failure). The chance of occurrence of some of those threats may be small in a particular well design. But, in other configurations, it may be known already at the planning stage that potential drilling problems are likely, because of tight operational margins for instance. The drilling challenges also may be aggravated by uncertainties in the geological context. Making a robust drilling-operation plan is a challenge, and there are many reasons for this. One of them is connected to the difficulty in evaluating quantitatively, at the planning stage, the effect of uncertain information on the effective risk levels that may prevail during well construction. Quantitative risk assessment with management of uncertainty has been described for specific tasks, such as choosing a mud weight as a function of an uncertain geopressure window. The more risks that are simultaneously evaluated within the expected uncertainty of the coming operation, the greater the chances are that the proposed drilling-operation plan will be robust. Drilling-Operation Risks Numerous sources of risk exist in a drilling operation, and the quality of the evaluation made by the proposed risk-evaluation method is directly related to treating as many threat sources as possible. However, it is an overwhelming task to manage all of the conceivable potential sources of drilling problems at once. For this reason, the authors decided that, as a first step, only a subset of possible causes of drilling incidents will be considered. The causes from this initial list are associated with typical problems encountered in drilling operations in the North Sea.

Organizational Trust and Fear of Injury and the Correlates of Organizational Trust Among Private Correctional Staff

ABSTRACTThe use of private corrections has grown to over 400 facilities in the United States. The staff are of particular importance in facilities operating on a tight profit margin. Maximizing profitability depends upon minimizing workplace factors that detract from staff performance and/or create costly strain. This study explored organizational trust and its link to fear of being hurt at work. A path model was tested to explore how various workplace variables relate to perceptions of organizational trust as well as how personal characteristics and organizational trust are associated with fear of injury. The results indicate that organizational trust appears to be one variable that influences staff perceptions of fear of injury. Increased levels of organizational trust decrease the fear of being injured at work.

Application of Superconducting Flywheel Energy Storage System to Inertia-Free Stand-Alone Microgrid

Recently, electric power systems have been operating with tight margins and have reached their operational limits. Many researchers consider a microgrid as one of the best solutions to relieve that problem. The microgrid is generally powered by renewable energies that are connected through power converters. In contrast to the rotational machines in the conventional power plants, the converters do not have physical rotors, and therefore they do not have rotational inertia. Consequently, a stand-alone microgrid has no inertia when it is powered by the only converter-based-generators (CBGs). As a result, the relationship between power and frequency is not valid, and the grid frequency cannot represent the power balance between the generator and load. In this paper, a superconducting flywheel energy storage system (SFESS) is applied to an inertia-free stand-alone (IFSA) microgrid. The SFESS accelerates or decelerates its rotational speed by storing or releasing power, respectively, based on its rotational inertia. Then, power in the IFSA microgrid can be balanced by measuring the rotor speed in the SFESS. This method does not have an error accumulation problem, which must be considered for the state of charge (SOC) estimation in the battery energy storage system (BESS). The performance of the proposed method is verified by an electromagnetic transient (EMT) simulation.

Analysis on Special Protection Scheme of Korea Electric Power System by Fully Utilizing STATCOM in a Generation Side

Increase in power demand has required providing infrastructure, such as huge power plants and transmission lines. However, the recent trends in power system planning and operation are being toward maximum utilization of existing electricity infrastructure with tight operating margins because of new constraints placed by economic, political, and environmental issues. This might cause serious stability problems when a severe fault or a sudden outage of critical lines occurs. Therefore, the special protection scheme (SPS) has been used by generator tripping and successive load shedding to prevent a large-scale blackout by the cascading effect. If the number of tripping generators in the SPS operation is reduced, the enormous cost of power outage can be saved. This paper analyzes the enhancement of SPS via the transient stability improvement by the static synchronous compensator (STATCOM) applied to a generation side of Korea electric power system. First, its characteristic related to the SPS is described. Then, the proper capacity of STATCOM is determined with the equal area criterion to reduce the number of tripping generators. Also, the new control method for STATCOM is proposed for its full utilization. Finally, its effectiveness is verified by the case study with the practical data of Korea electric power system.

Peace is on the Ballot: The Politicization of the Colombian Peace Talks

On October 2nd 2016, Colombian voters rejected a referendum on the peace agreement between the federal government and the Revolutionary Armed Forces of Colombia (FARC). Contrary to most advance polling and preliminary estimates in national and international news media, the “No” vote won by a tight margin, thus rejecting a peace deal that would have brought an end to the longest civil war in the Western hemisphere. This paper examines the intersections of civil society and the political groups most actively involved in the peace process in Colombia, beginning in the 1980s and leading to the 2016 referendum. The findings are two-fold: first, civil society has played an integral role in both the endurance and the hindrance of the peace process from its beginnings in 1980s up to the present day, through electoral support of independent candidates and by mobilization of special interest groups. Second, the 2016 referendum results share exceptional demographic and geographic correlations with the results of the 2014 presidential election. This suggests the peace referendum was highly politicized and split along the lines of partisanship at the highest echelons of Colombian democracy.

An optimization-simulation approach to the network redesign problem of pharmaceutical wholesalers

The pharmaceutical industry operates in a very competitive and regulated market. The increased pressure of pharmacies to order fewer products and to receive them more frequently is overcharging the pharmaceutical’s distribution network. Furthermore, the tight margins and the continuous growth of generic drugs consumption are pressing wholesalers to optimize their supply chains. In order to survive, wholesalers are rethinking their strategies to increase competitiveness. This paper proposes an optimization-simulation approach to address the wholesalers network redesign problem, trading off the operational costs and customer service level. Firstly, at a strategic-tactical level, the supply chain network redesign decisions are optimized via a mixed integer programming model. Here, the number, location, function and capacity of the warehouses, the allocation of customers to the warehouses and the capacity and function of the distribution channels are defined. Secondly, at an operation level, the solution found is evaluated by means of a discrete event simulation model to assess the impact of the redesign in the wholesaler’s daily activities. Computational results on a pharmaceutical wholesaler case-study are discussed and the benefits of this solution approach exposed.

SC16.03 Radiotherapy for Sulcus Superior Tumors

SC16.03 Radiotherapy for Sulcus Superior Tumors

Margin Requirements and Systemic Liquidity Risk

We develop a model in which margin procyclicality and the propensity for liquidity hoarding interact to generate a systemic liquidity crisis. In this model, banks lend and borrow in the interbank market to mitigate liquidity risk and trade derivatives contracts in the OTC derivatives market to mitigate market risk. The daily mark-to-market of derivatives contracts results in daily margin calls that banks cover using high quality liquid assets. We find that distress due to margin procyclicality in the derivatives market can spillover to the interbank market leading to systemic liquidity risk. Interconnectedness further amplifies the effects of systemic risk within the interbank market. The model shows that central clearing might increase the possibility of systemic liquidity risk due to tight margin requirements and the timing of cash flows required from banks. We also find that haircut levels affect the possibility of systemic liquidity risk, and highlight the potential role of a market maker of last resort in limiting this possibility.

Radiothérapie stéréotaxique des métastases osseuses vertébrales

After the liver and lungs, bones are the third most common sites of cancer metastasis. Palliative radiotherapy for secondary bone tumours helps relieve pain, improve the quality of life and reduce the risk of fractures. Stereotactic body radiotherapy can deliver high radiation doses with very tight margins, which has significant advantages when treating tumours close to the spinal cord. Strict quality control is essential as dose gradient at the edge of the spinal cord is important. Optimal schedule is not defined. A range of dose-fractionation schedules have been used. Pain relief and local control are seen in over 80%. Toxicity rates are low, although vertebral fracture may occur. Ongoing prospective studies will help clarify its role in the management of oligometastatic patients.

Sci‐Thur PM – Brachytherapy 06: 3D Printed Surface Applicators for High Dose Rate Brachytherapy

Purpose:The purpose of this work is to develop a new applicator for administering high dose rate (HDR) brachytherapy using 3D printing technology. Primary advantages of using a 3D printed applicator will be to offer a more streamlined approach for therapists and patients while achieving better conformity, reproducibility, and patient specific applicators.Methods:A phantom study was conducted to measure the effectiveness of a 3D printed surface applicator by analyzing tumours on three locations of the body: the foot, nose, and scalp. The applicator was designed using Eclipse and further modified using Blender to create the catheter tunnels before being printed on a Lulzbot Taz 5 3D printer. A radiation plan was made using Oncentra Brachytherapy for a control treatment option using Freiburg Flaps and one with the novel method of a 3D printed applicator. A comparative analysis was made using D90, D100, V100, V150, and V200Results:The 3D printed applicator showed comparable dose coverage with significant improvements on highly irregular surfaces when analyzed against a plan made using Freiburg Flaps. Although both plans exhibited complete tumour coverage, the 3D applicator showed improvements in D90 and V150 and the 3D applicator had a dose homogeneity index (DHI) of 0.99 compared to a DHI of 0.97 for the control. Therapist prep time also dropped significantly due to the lack of need for a thermoplastic mesh.Conclusions:3D printed applicators for treatment of superficial sites proved to offer more patient convenience, less prep time, better conformity and tighter margins.

Sci‐Thur PM – Brachytherapy 05: Surface Collimation Applied to Superficial Flap High Dose‐Rate Brachytherapy

Purpose:To apply surface collimation for superficial flap HDR skin brachytherapy utilizing common clinical resources and to demonstrate the potential for OAR dose reduction within a clinically relevant setting.Methods:Two phantom setups were used. 3 mm lead collimation was applied to a solid slab phantom to determine appropriate geometries relating to collimation and dwell activation. The same collimation was applied to the temple of an anthropomorphic head phantom to demonstrate lens dose reduction. Each setup was simulated and planned to deliver 400 cGy to a 3 cm circular target to 3 mm depth. The control and collimated irradiations were sequentially measured using calibrated radiochromic films.Results:Collimation for the slab phantom attenuated the dose beyond the collimator opening, decreasing the fall‐off distances by half and reducing the area of healthy skin irradiated. Target coverage can be negatively impacted by a tight collimation margin, with the required margin approximated by the primary beam geometric penumbra.Surface collimation applied to the head phantom similarly attenuated the surrounding normal tissue dose while reducing the lens dose from 84 to 68 cGy. To ensure consistent setup between simulation and treatment, additional QA was performed including collimator markup, accounting for collimator placement uncertainties, standoff distance verification, and in vivo dosimetry.Conclusions:Surface collimation was shown to reduce normal tissue dose without compromising target coverage. Lens dose reduction was demonstrated on an anthropomorphic phantom within a clinical setting. Additional QA is proposed to ensure treatment fidelity.

Interfraction Anatomical Variability Can Lead to Significantly Increased Rectal Dose for Patients Undergoing Stereotactic Body Radiotherapy for Prostate Cancer.

Stereotactic body radiotherapy for prostate cancer is rapidly growing in popularity. Stereotactic body radiotherapy plans mimic those of high-dose rate brachytherapy, with tight margins and inhomogeneous dose distributions. The impact of interfraction anatomical changes on the dose received by organs at risk under these conditions has not been well documented. To estimate anatomical variation during stereotactic body radiotherapy, 10 patients were identified who received a prostate boost using robotic stereotactic body radiotherapy after completing 25 fractions of pelvic radiotherapy with daily megavoltage computed tomography. Rectal and bladder volumes were delineated on each megavoltage computed tomography, and the stereotactic body radiotherapy boost plan was registered to each megavoltage computed tomography image using a point-based rigid registration with 3 fiducial markers placed in the prostate. The volume of rectum and bladder receiving 75% of the prescription dose (V75%) was measured for each megavoltage computed tomography. The rectal V75% from the daily megavoltage computed tomographies was significantly greater than the planned V75% (median increase of 0.93 cm3, P < .001), whereas the bladder V75% on megavoltage computed tomography was not significantly changed (median decrease of -0.12 cm3, P = .57). Although daily prostate rotation was significantly correlated with bladder V75% (Spearman ρ = .21, P = .023), there was no association between rotation and rectal V75% or between prostate deformation and either rectal or bladder V75%. Planning organ-at-risk volume-based replanning techniques using either a 6-mm isotropic expansion of the plan rectal contour or a 1-cm expansion from the planning target volume in the superior and posterior directions demonstrated significantly improved rectal V75% on daily megavoltage computed tomographies compared to the original stereotactic body radiotherapy plan, without compromising plan quality. Thus, despite tight margins and full translational and rotational corrections provided by robotic stereotactic body radiotherapy, we find that interfraction anatomical variations can lead to a substantial increase in delivered rectal doses during prostate stereotactic body radiotherapy. A planning organ-at-risk volume-based approach to treatment planning may help mitigate the impact of daily organ motion and reduce the risk of rectal toxicity.

Balancing Power Systems With Datacenters Using a Virtual Interconnector

Balancing electricity supply and demand is a complex task. Renewable energy sources are often intermittent, while electrical loads vary throughout the day. This can result in an abundant supply that suppresses spot prices in one region, while another region simultaneously experiences tight supply margins and price spikes. Connecting these two regions through electrical interconnectors would enable greater utilization of renewable energy, but this can be expensive and is unfeasible for distant regions, such as between continents. However, datacenters are becoming ubiquitous around the world and are linked through fiber connections. This paper proposes a virtual interconnector (VIC) scheme using fiber to dynamically move energy demand, in the form of computation, to datacenters in other market regions with surplus low cost and renewable energy. This increases the global renewable penetration without requiring expensive grid interconnections. The associated benefits for the datacenter operator, the electricity grid controller, consumers, and the environment are discussed.

The Power of Cognitive Technology

Management It has been over a year since Repsol and IBM announced their plans to jointly develop cognitive technologies that would allow human decision makers operating in the oil and gas industry to interact with computers more effectively, enhancing the industry’s ability to source, analyze, and filter big data to make it more consumable. Building on what is commonly referred to as artificial intelligence, experts in this field are developing “super computers,” which are able to understand, learn from, and interact with humans. Many different companies in various sectors are currently developing cognitive technologies for specific activities, with the most pioneering being applied to the exploration and production (E&amp;P) sector of oil and gas. In an environment of low oil prices and ever tighter margins, cognitive technology can help energy companies increase the productivity of their oil and gas fields and minimize exploration risk when searching for new resources. The objectives of Repsol’s collaboration with IBM were twofold: to leverage cognitive computing capabilities to specifically help Repsol reduce the risk and uncertainty of future oil field acquisitions and to maximize the yield of existing oil fields—both of which can have a significant impact on the efficiency of global E&amp;P operations of Repsol and other oil and gas companies. Currently, offshore E&amp;P is a capital-intensive exercise. The drilling of a single well can cost up to USD 400 million and the data used to determine the best location to search and drill for oil are often extremely limited and inaccurate. By developing these cognitive technologies, Repsol and IBM have been able to bring decision makers together, helping them to share insights, gather data sets from multiple sources more easily, and enable better, more prescriptive analysis. The ability to overcome limitations posed by big data has led to less uncertainty and, ultimately, reduced operational risk. Optimizing Reservoir Production Looking specifically to the optimization of reservoir production, a cognitive environment can adapt to the individual needs of a varied set of technical experts, equipping them with the tools needed to enhance their abilities to analyze data from varied sources. Technicians have also been able to tie in existing production models with the analyzed data and adjust them to more accurately match current production as time goes on. Inspiration came in part from Repsol’s Excalibur project, launched with the objective of optimizing deposits. The project, tested in remote offshore fields in Ecuador and Brazil, was a combination of tools developed at the Repsol Technology Center. Excalibur uses mathematical techniques to comprehensively identify and evaluate deposits, optimize their development, and minimize risk. The tool enables a deposit portfolio to be quickly and accurately ranked and new investment opportunities to be identified that are difficult to detect using traditional techniques. In the tests carried out on a North Sea deposit, Excalibur achieved an improvement of 9% on the best solution published to date by other research companies and institutions.