Sci—Thur PM: Planning and Delivery — 04: Respiratory margin derivation and verification in partial breast irradiation

International Nuclear Information System (INIS)

Quirk, S; Conroy, L; Smith, WL

2014-01-01

Partial breast irradiation (PBI) following breast-conserving surgery is emerging as an effective means to achieve local control and reduce irradiated breast volume. Patients are planned on a static CT image; however, treatment is delivered while the patient is free-breathing. Respiratory motion can degrade plan quality by reducing target coverage and/or dose homogeneity. A variety of methods can be used to determine the required margin for respiratory motion in PBI. We derive geometric and dosimetric respiratory 1D margin. We also verify the adequacy of the typical 5 mm respiratory margin in 3D by evaluating plan quality for increasing respiratory amplitudes (2–20 mm). Ten PBI plans were used for dosimetric evaluation. A database of volunteer respiratory data, with similar characteristics to breast cancer patients, was used for this study. We derived a geometric 95%-margin of 3 mm from the population respiratory data. We derived a dosimetric 95%-margin of 2 mm by convolving 1D dose profiles with respiratory probability density functions. The 5 mm respiratory margin is possibly too large when 1D coverage is assessed and could lead to unnecessary normal tissue irradiation. Assessing margins only for coverage may be insufficient; 3D dosimetric assessment revealed degradation in dose homogeneity is the limiting factor, not target coverage. Hotspots increased even for the smallest respiratory amplitudes, while target coverage only degraded at amplitudes greater than 10 mm. The 5 mm respiratory margin is adequate for coverage, but due to plan quality degradation, respiratory management is recommended for patients with respiratory amplitudes greater than 10 mm

Assessment of tsunami hazard to the U.S. Atlantic margin

Science.gov (United States)

ten Brink, Uri S.; Chaytor, Jason; Geist, Eric L.; Brothers, Daniel S.; Andrews, Brian D.

2014-01-01

Tsunami hazard is a very low-probability, but potentially high-risk natural hazard, posing unique challenges to scientists and policy makers trying to mitigate its impacts. These challenges are illustrated in this assessment of tsunami hazard to the U.S. Atlantic margin. Seismic activity along the U.S. Atlantic margin in general is low, and confirmed paleo-tsunami deposits have not yet been found, suggesting a very low rate of hazard. However, the devastating 1929 Grand Banks tsunami along the Atlantic margin of Canada shows that these events continue to occur. Densely populated areas, extensive industrial and port facilities, and the presence of ten nuclear power plants along the coast, make this region highly vulnerable to flooding by tsunamis and therefore even low-probability events need to be evaluated.

Energy system analyses of the marginal energy technology in life cycle assessments

DEFF Research Database (Denmark)

Mathiesen, B.V.; Münster, Marie; Fruergaard, Thilde

2007-01-01

in historical and potential future energy systems. Subsequently, key LCA studies of products and different waste flows are analysed in relation to the recom- mendations in consequential LCA. Finally, a case of increased waste used for incineration is examined using an energy system analysis model......In life cycle assessments consequential LCA is used as the “state-of-the-art” methodology, which focuses on the consequences of decisions made in terms of system boundaries, allocation and selection of data, simple and dynamic marginal technology, etc.(Ekvall & Weidema 2004). In many LCA studies...... marginal technology? How is the marginal technology identified and used today? What is the consequence of not using energy system analy- sis for identifying the marginal energy technologies? The use of the methodology is examined from three angles. First, the marginal electricity technology is identified...

Customized Computed Tomography-Based Boost Volumes in Breast-Conserving Therapy: Use of Three-Dimensional Histologic Information for Clinical Target Volume Margins

International Nuclear Information System (INIS)

Hanbeukers, Bianca; Borger, Jacques; Ende, Piet van den; Ent, Fred van der; Houben, Ruud; Jager, Jos; Keymeulen, Kristien; Murrer, Lars; Sastrowijoto, Suprapto; Vijver, Koen van de; Boersma, Liesbeth

2009-01-01

Purpose: To determine the difference in size between computed tomography (CT)-based irradiated boost volumes and simulator-based irradiated volumes in patients treated with breast-conserving therapy and to analyze whether the use of anisotropic three-dimensional clinical target volume (CTV) margins using the histologically determined free resection margins allows for a significant reduction of the CT-based boost volumes. Patients and Methods: The CT data from 49 patients were used to delineate a planning target volume (PTV) with isotropic CTV margins and to delineate a PTV sim that mimicked the PTV as delineated in the era of conventional simulation. For 17 patients, a PTV with anisotropic CTV margins was defined by applying customized three-dimensional CTV margins, according to the free excision margins in six directions. Boost treatment plans consisted of conformal portals for the CT-based PTVs and rectangular fields for the PTV sim . Results: The irradiated volume (volume receiving ≥95% of the prescribed dose [V 95 ]) for the PTV with isotropic CTV margins was 1.6 times greater than that for the PTV sim : 228 cm 3 vs. 147 cm 3 (p 95 was similar to the V 95 for the PTV sim (190 cm 3 vs. 162 cm 3 ; p = NS). The main determinant for the irradiated volume was the size of the excision cavity (p < .001), which was mainly related to the interval between surgery and the planning CT scan (p = .029). Conclusion: CT-based PTVs with isotropic margins for the CTV yield much greater irradiated volumes than fluoroscopically based PTVs. Applying individualized anisotropic CTV margins allowed for a significant reduction of the irradiated boost volume.

Stereotactic Radiosurgery of the Postoperative Resection Cavity for Brain Metastases: Prospective Evaluation of Target Margin on Tumor Control

International Nuclear Information System (INIS)

Choi, Clara Y.H.; Chang, Steven D.; Gibbs, Iris C.; Adler, John R.; Harsh, Griffith R.; Lieberson, Robert E.; Soltys, Scott G.

2012-01-01

Purpose: Given the neurocognitive toxicity associated with whole-brain irradiation (WBRT), approaches to defer or avoid WBRT after surgical resection of brain metastases are desirable. Our initial experience with stereotactic radiosurgery (SRS) targeting the resection cavity showed promising results. We examined the outcomes of postoperative resection cavity SRS to determine the effect of adding a 2-mm margin around the resection cavity on local failure (LF) and toxicity. Patients and Methods: We retrospectively evaluated 120 cavities in 112 patients treated from 1998-2009. Factors associated with LF and distant brain failure (DF) were analyzed using competing risks analysis, with death as a competing risk. The overall survival (OS) rate was calculated by the Kaplan-Meier product-limit method; variables associated with OS were evaluated using the Cox proportional hazards and log rank tests. Results: The 12-month cumulative incidence rates of LF and DF, with death as a competing risk, were 9.5% and 54%, respectively. On univariate analysis, expansion of the cavity with a 2-mm margin was associated with decreased LF; the 12-month cumulative incidence rates of LF with and without margin were 3% and 16%, respectively (P=.042). The 12-month toxicity rates with and without margin were 3% and 8%, respectively (P=.27). On multivariate analysis, melanoma histology (P=.038) and number of brain metastases (P=.0097) were associated with higher DF. The median OS time was 17 months (range, 2-114 months), with a 12-month OS rate of 62%. Overall, WBRT was avoided in 72% of the patients. Conclusion: Adjuvant SRS targeting the resection cavity of brain metastases results in excellent local control and allows WBRT to be avoided in a majority of patients. A 2-mm margin around the resection cavity improved local control without increasing toxicity compared with our prior technique with no margin.

Developing tools to identify marginal lands and assess their potential for bioenergy production

Science.gov (United States)

Galatsidas, Spyridon; Gounaris, Nikolaos; Dimitriadis, Elias; Rettenmaier, Nils; Schmidt, Tobias; Vlachaki, Despoina

2017-04-01

The term "marginal land" is currently intertwined in discussions about bioenergy although its definition is neither specific nor firm. The uncertainty arising from marginal land classification and quantification is one of the major constraining factors for its potential use. The clarification of political aims, i.e. "what should be supported?" is also an important constraining factor. Many approaches have been developed to identify marginal lands, based on various definitions according to the management goals. Concerns have been frequently raised regarding the impacts of marginal land use on environment, ecosystem services and sustainability. Current tools of soil quality and land potentials assessment fail to meet the needs of marginal land identification and exploitation for biomass production, due to the lack of comprehensive analysis of interrelated land functions and their quantitative evaluation. Land marginality is determined by dynamic characteristics in many cases and may therefore constitute a transitional state, which requires reassessment in due time. Also, marginal land should not be considered simply a dormant natural resource waiting to be used, since it may already provide multiple benefits and services to society relating to wildlife, biodiversity, carbon sequestration, etc. The consequences of cultivating such lands need to be fully addressed to present a balanced view of their sustainable potential for bioenergy. This framework is the basis for the development of the SEEMLA tools, which aim at supporting the identification, assessment, management of marginal lands in Europe and the decision-making for sustainable biomass production of them using appropriate bioenergy crops. The tools comprise two applications, a web-based one (independent of spatial data) and a GIS-based application (land regionalization on the basis of spatial data), which both incorporate: - Land resource characteristics, restricting the cultivation of agricultural crops but

WSEAT Shock Testing Margin Assessment Using Energy Spectra Final Report.

Energy Technology Data Exchange (ETDEWEB)

Sisemore, Carl; Babuska, Vit; Booher, Jason

2018-02-01

Several programs at Sandia National Laboratories have adopted energy spectra as a metric to relate the severity of mechanical insults to structural capacity. The purpose being to gain insight into the system's capability, reliability, and to quantify the ultimate margin between the normal operating envelope and the likely system failure point -- a system margin assessment. The fundamental concern with the use of energy metrics was that the applicability domain and implementation details were not completely defined for many problems of interest. The goal of this WSEAT project was to examine that domain of applicability and work out the necessary implementation details. The goal of this project was to provide experimental validation for the energy spectra based methods in the context of margin assessment as they relate to shock environments. The extensive test results concluded that failure predictions using energy methods did not agree with failure predictions using S-N data. As a result, a modification to the energy methods was developed following the form of Basquin's equation to incorporate the power law exponent for fatigue damage. This update to the energy-based framework brings the energy based metrics into agreement with experimental data and historical S-N data.

Determining optimal clinical target volume margins in head-and-neck cancer based on microscopic extracapsular extension of metastatic neck nodes

International Nuclear Information System (INIS)

Apisarnthanarax, Smith; Elliott, Danielle D.; El-Naggar, Adel K.; Asper, Joshua A. P.A.; Blanco, Angel; Ang, K. Kian; Garden, Adam S.; Morrison, William H.; Rosenthal, David; Weber, Randal S.; Chao, K.S. Clifford

2006-01-01

Purpose: To determine the optimal clinical target volume margins around the gross nodal tumor volume in head-and-neck cancer by assessing microscopic tumor extension beyond cervical lymph node capsules. Methods and Materials: Histologic sections of 96 dissected cervical lymph nodes with extracapsular extension (ECE) from 48 patients with head-and-neck squamous cell carcinoma were examined. The maximum linear distance from the external capsule border to the farthest extent of the tumor or tumoral reaction was measured. The trends of ECE as a function of the distance from the capsule and lymph node size were analyzed. Results: The median diameter of all lymph nodes was 11.0 mm (range: 3.0-30.0 mm). The mean and median ECE extent was 2.2 mm and 1.6 mm, respectively (range: 0.4-9.0 mm). The ECE was <5 mm from the capsule in 96% of the nodes. As the distance from the capsule increased, the probability of tumor extension declined. No significant difference between the extent of ECE and lymph node size was observed. Conclusion: For N1 nodes that are at high risk for ECE but not grossly infiltrating musculature, 1 cm clinical target volume margins around the nodal gross tumor volume are recommended to cover microscopic nodal extension in head-and-neck cancer

Is it necessary to plan with safety margins for actively scanned proton therapy?

Science.gov (United States)

Albertini, F.; Hug, E. B.; Lomax, A. J.

2011-07-01

In radiation therapy, a plan is robust if the calculated and the delivered dose are in agreement, even in the case of different uncertainties. The current practice is to use safety margins, expanding the clinical target volume sufficiently enough to account for treatment uncertainties. This, however, might not be ideal for proton therapy and in particular when using intensity modulated proton therapy (IMPT) plans as degradation in the dose conformity could also be found in the middle of the target resulting from misalignments of highly in-field dose gradients. Single field uniform dose (SFUD) and IMPT plans have been calculated for different anatomical sites and the need for margins has been assessed by analyzing plan robustness to set-up and range uncertainties. We found that the use of safety margins is a good way to improve plan robustness for SFUD and IMPT plans with low in-field dose gradients but not necessarily for highly modulated IMPT plans for which only a marginal improvement in plan robustness could be detected through the definition of a planning target volume.

On-line fatigue monitoring and margins probabilistic assessment

International Nuclear Information System (INIS)

Fournier, I.; Morilhat, P.

1993-01-01

An on-line computer aided system has been developed by Electricite de France, the French utility, for a fatigue monitoring of critical locations in the nuclear steam supply system. This tool, called fatiguemeter, includes as input data only existing plant parameters and is based on some conservative assumptions at several steps of the damage assessment (thermal boundary conditions, stress computation...). This paper presents recent developments performed toward a better assessing of margins involved in the complete analysis. The methodology is enlightened with an example showing the influence of plant parameters incertitude on the final stress computed at a PWR 900 MW unit pressurizer surge line nozzle. (author)

Market modeling for assessment of demand side programs using the marginal cost

International Nuclear Information System (INIS)

Papastamatiou, Panagiotis; Psarras, John

2000-01-01

Demand side management is nowadays considered as a functional step in the energy planning process. The criteria proposed for the assessment of the demand side programs (DSPs) are usually based on the balance between the marginal supply cost and the mean DSP cost. These criteria could not support the allotting of the invested capital to incentives for the consumers and advertising. This paper presents a methodology to support the utility planning at this point with more reliability. It proposes the expansion of the assessment criteria with the use of the marginal cost of the DSP. For the calculation of the DSP marginal cost, a dynamic model is developed and it is used for the simulation of the penetration of a DS Program. Using the 'least-cost' criterion as the decision rule for the simulation, the planner has a distribution of the available investment capital throughout the whole planning period. The use of the 'most-value' criterion supports the separation of the invested capital between incentives for the consumers and supportive expenses, e.g. advertising, marketing cost, etc. (Author)

A novel respiratory motion compensation strategy combining gated beam delivery and mean target position concept - A compromise between small safety margins and long duty cycles

International Nuclear Information System (INIS)

Guckenberger, Matthias; Kavanagh, Anthony; Webb, Steve; Brada, Michael

2011-01-01

Purpose: To evaluate a novel respiratory motion compensation strategy combining gated beam delivery with the mean target position (MTP) concept for pulmonary stereotactic body radiotherapy (SBRT). Materials and methods: Four motion compensation strategies were compared for 10 targets with motion amplitudes between 6 mm and 31 mm: the internal target volume concept (plan ITV ); the MTP concept where safety margins were adapted based on 4D dose accumulation (plan MTP ); gated beam delivery without margins for motion compensation (plan gated ); a novel approach combining gating and the MTP concept (plan gated and MTP ). Results: For 5/10 targets with an average motion amplitude of 9 mm, the differences in the mean lung dose (MLD) between plan gated and plan MTP were gated and MTP . Despite significantly shorter duty cycles, plan gated reduced the MLD by gated and MTP . The MLD was increased by 18% in plan MTP compared to that of plan gated and MTP . Conclusions: For pulmonary targets with motion amplitudes >10-15 mm, the combination of gating and the MTP concept allowed small safety margins with simultaneous long duty cycles.

Planning Target Margin Calculations for Prostate Radiotherapy Based on Intrafraction and Interfraction Motion Using Four Localization Methods

International Nuclear Information System (INIS)

Beltran, Chris; Herman, Michael G.; Davis, Brian J.

2008-01-01

Purpose: To determine planning target volume (PTV) margins for prostate radiotherapy based on the internal margin (IM) (intrafractional motion) and the setup margin (SM) (interfractional motion) for four daily localization methods: skin marks (tattoo), pelvic bony anatomy (bone), intraprostatic gold seeds using a 5-mm action threshold, and using no threshold. Methods and Materials: Forty prostate cancer patients were treated with external radiotherapy according to an online localization protocol using four intraprostatic gold seeds and electronic portal images (EPIs). Daily localization and treatment EPIs were obtained. These data allowed inter- and intrafractional analysis of prostate motion. The SM for the four daily localization methods and the IM were determined. Results: A total of 1532 fractions were analyzed. Tattoo localization requires a SM of 6.8 mm left-right (LR), 7.2 mm inferior-superior (IS), and 9.8 mm anterior-posterior (AP). Bone localization requires 3.1, 8.9, and 10.7 mm, respectively. The 5-mm threshold localization requires 4.0, 3.9, and 3.7 mm. No threshold localization requires 3.4, 3.2, and 3.2 mm. The intrafractional prostate motion requires an IM of 2.4 mm LR, 3.4 mm IS and AP. The PTV margin using the 5-mm threshold, including interobserver uncertainty, IM, and SM, is 4.8 mm LR, 5.4 mm IS, and 5.2 mm AP. Conclusions: Localization based on EPI with implanted gold seeds allows a large PTV margin reduction when compared with tattoo localization. Except for the LR direction, bony anatomy localization does not decrease the margins compared with tattoo localization. Intrafractional prostate motion is a limiting factor on margin reduction

Fracture mechanics characteristics and associated safety margins for integrity assessment; Bruchmechanische Kennwerte und zugeordnete Sicherheitsfaktoren bei Integritaetsanalysen

Energy Technology Data Exchange (ETDEWEB)

Roos, E.; Schuler, X.; Stumpfrock, L.; Silcher, H. [Stuttgart Univ. (DE). Materialpruefungsanstalt (MPA)

2008-07-01

Within the integrity assessment of components and structural members of plants safety margins have to be applied, whose magnitude depend on several factors. Important factors influencing the magnitude of the safety margins are as for instance: Material behaviour (ductile / brittle behaviour), the event to be considered (local deformation / fracture), possible consequences of failure (human health, environmental damage, economic consequences) and many others. One important factor also is the fact, how precisely and reliably the appropriate material characteristics can be determined and how precisely and reliably the components behaviour can be predicted and assessed by means of this material characteristic. In contemporary safety assessment procedures by means of fracture mechanics evaluation tools (e.g. [1]) a concept of partial safety margins is proposed for application. The basic idea with this procedure is that only those sources of uncertainty have to be considered, which are relevant or may be relevant for the structure to be considered. For this purpose each source of possible uncertainty has to be quantified individually, finally only those singular safety margins are superimposed to a total safety margin which are relevant. The more the uncertainties have to be taken into account, the total safety margin to be applied, consequently will be larger. If some sources of uncertainty can be eliminated totally or can be minimized (for instance by a more reliable calculational procedure of the component loading or by more precise material characteristics), the total safety margin can be reduced. In this contribution the different procedures for the definition of safety margins within the integrity assessment by means of fracture mechanics procedures will be discussed. (orig.)

Craniocaudal Safety Margin Calculation Based on Interfractional Changes in Tumor Motion in Lung SBRT Assessed With an EPID in Cine Mode

International Nuclear Information System (INIS)

Ueda, Yoshihiro; Miyazaki, Masayoshi; Nishiyama, Kinji; Suzuki, Osamu; Tsujii, Katsutomo; Miyagi, Ken

2012-01-01

Purpose: To evaluate setup error and interfractional changes in tumor motion magnitude using an electric portal imaging device in cine mode (EPID cine) during the course of stereotactic body radiation therapy (SBRT) for non–small-cell lung cancer (NSCLC) and to calculate margins to compensate for these variations. Materials and Methods: Subjects were 28 patients with Stage I NSCLC who underwent SBRT. Respiratory-correlated four-dimensional computed tomography (4D-CT) at simulation was binned into 10 respiratory phases, which provided average intensity projection CT data sets (AIP). On 4D-CT, peak-to-peak motion of the tumor (M-4DCT) in the craniocaudal direction was assessed and the tumor center (mean tumor position [MTP]) of the AIP (MTP-4DCT) was determined. At treatment, the tumor on cone beam CT was registered to that on AIP for patient setup. During three sessions of irradiation, peak-to-peak motion of the tumor (M-cine) and the mean tumor position (MTP-cine) were obtained using EPID cine and in-house software. Based on changes in tumor motion magnitude (∆M) and patient setup error (∆MTP), defined as differences between M-4DCT and M-cine and between MTP-4DCT and MTP-cine, a margin to compensate for these variations was calculated with Stroom’s formula. Results: The means (±standard deviation: SD) of M-4DCT and M-cine were 3.1 (±3.4) and 4.0 (±3.6) mm, respectively. The means (±SD) of ∆M and ∆MTP were 0.9 (±1.3) and 0.2 (±2.4) mm, respectively. Internal target volume-planning target volume (ITV-PTV) margins to compensate for ∆M, ∆MTP, and both combined were 3.7, 5.2, and 6.4 mm, respectively. Conclusion: EPID cine is a useful modality for assessing interfractional variations of tumor motion. The ITV-PTV margins to compensate for these variations can be calculated.

Towards intraoperative assessment of tumor margins in breast surgery using optical coherence elastography (Conference Presentation)

Science.gov (United States)

Kennedy, Brendan F.; Wijesinghe, Philip; Allen, Wes M.; Chin, Lixin; Latham, Bruce; Saunders, Christobel M.; Sampson, David D.

2016-03-01

Surgical excision of tumor is a critical factor in the management of breast cancer. The most common surgical procedure is breast-conserving surgery. The surgeon's goal is to remove the tumor and a rim of healthy tissue surrounding the tumor: the surgical margin. A major issue in breast-conserving surgery is the absence of a reliable tool to guide the surgeon in intraoperatively assessing the margin. A number of techniques have been proposed; however, the re-excision rate remains high and has been reported to be in the range 30-60%. New tools are needed to address this issue. Optical coherence elastography (OCE) shows promise as a tool for intraoperative tumor margin assessment in breast-conserving surgery. Further advances towards clinical translation are limited by long scan times and small fields of view. In particular, scanning over sufficient areas to assess the entire margin in an intraoperative timeframe has not been shown to be feasible. Here, we present a protocol allowing ~75% of the surgical margins to be assessed within 30 minutes. To achieve this, we have incorporated a 65 mm-diameter (internal), wide-aperture annular piezoelectric transducer, allowing the entire surface of the excised tumor mass to be automatically imaged in an OCT mosaic comprised of 10 × 10 mm tiles. As OCT is effective in identifying adipose tissue, our protocol uses the wide-field OCT to selectively guide subsequent local OCE scanning to regions of solid tissue which often present low contrast in OCT images. We present promising examples from freshly excised human breast tissue.

SU-E-J-88: Margin Reduction of Level II/III Planning Target Volume for Image-Guided Simultaneous Integrated Boost Head-And-Neck Treatment

International Nuclear Information System (INIS)

Can, S; Neylon, J; Qi, S; Santhanam, A; Low, D

2014-01-01

Purpose: To investigate the feasibility of improved normal tissue sparing for head-and-neck (H'N) image-guided radiotherapy (IGRT) by employing tighter CTV-to-PTV margins for target level II/III though a GPU-based deformable image registration and dose accumulation framework. Methods: Ten H'N simultaneous integrated boost cases treated on TomoTherapy were retrospectively analyzed. Weekly kVCT scans in addition to daily MVCT scans were acquired for each patient. Reduced margin plans were generated with 0- mm margin for level II and III PTV (while 3-5 mm margin for PTV1) and compared with the standard margin plan using 3-5mm margin to all CTV1-3 (reference plan). An in-house developed GPU-based 3D image deformation tool was used to register and deform the weekly KVCTs with the planning CT and determine the delivered mean/minimum/maximum dose, dose volume histograms (DVHs), etc. Results: Compared with the reference plans, the averaged cord maximum, the right and left parotid doses reduced by 22.7 %, 16.5 %, and 9 % respectively in the reduced margin plans. The V95 for PTV2 and PTV3 were found within 2 and 5% between the reference and tighter margin plans. For the reduced margin plans, the averaged cumulative mean doses were consistent with the planned dose for PTV1, PTV2 and PTV3 within 1.5%, 1.7% and 1.4%. Similar dose variations of the delivered dose were seen for the reference and tighter margin plans. The delivered maximum and mean doses for the cord were 3.55 % and 2.37% higher than the planned doses; a 5 % higher cumulative mean dose for the parotids was also observed for the delivered dose than the planned doses in both plans. Conclusion: By imposing tighter CTV-to-PTV margins for level II and III targets for H'N irradiation, acceptable cumulative doses were achievable when coupled with weekly kVCT guidance while improving normal structure sparing

Treatment simulations with a statistical deformable motion model to evaluate margins for multiple targets in radiotherapy for high-risk prostate cancer

International Nuclear Information System (INIS)

Thörnqvist, Sara; Hysing, Liv B.; Zolnay, Andras G.; Söhn, Matthias; Hoogeman, Mischa S.; Muren, Ludvig P.; Bentzen, Lise; Heijmen, Ben J.M.

2013-01-01

Background and purpose: Deformation and correlated target motion remain challenges for margin recipes in radiotherapy (RT). This study presents a statistical deformable motion model for multiple targets and applies it to margin evaluations for locally advanced prostate cancer i.e. RT of the prostate (CTV-p), seminal vesicles (CTV-sv) and pelvic lymph nodes (CTV-ln). Material and methods: The 19 patients included in this study, all had 7–10 repeat CT-scans available that were rigidly aligned with the planning CT-scan using intra-prostatic implanted markers, followed by deformable registrations. The displacement vectors from the deformable registrations were used to create patient-specific statistical motion models. The models were applied in treatment simulations to determine probabilities for adequate target coverage, e.g. by establishing distributions of the accumulated dose to 99% of the target volumes (D 99 ) for various CTV–PTV expansions in the planning-CTs. Results: The method allowed for estimation of the expected accumulated dose and its variance of different DVH parameters for each patient. Simulations of inter-fractional motion resulted in 7, 10, and 18 patients with an average D 99 >95% of the prescribed dose for CTV-p expansions of 3 mm, 4 mm and 5 mm, respectively. For CTV-sv and CTV-ln, expansions of 3 mm, 5 mm and 7 mm resulted in 1, 11 and 15 vs. 8, 18 and 18 patients respectively with an average D 99 >95% of the prescription. Conclusions: Treatment simulations of target motion revealed large individual differences in accumulated dose mainly for CTV-sv, demanding the largest margins whereas those required for CTV-p and CTV-ln were comparable

Dual in vivo Photoacoustic and Fluorescence Imaging of HER2 Expression in Breast Tumors for Diagnosis, Margin Assessment, and Surgical Guidance

Directory of Open Access Journals (Sweden)

Azusa Maeda

2015-01-01

Full Text Available Biomarker-specific imaging probes offer ways to improve molecular diagnosis, intraoperative margin assessment, and tumor resection. Fluorescence and photoacoustic imaging probes are of particular interest for clinical applications because the combination enables deeper tissue penetration for tumor detection while maintaining imaging sensitivity compared to a single optical imaging modality. Here we describe the development of a human epidermal growth factor receptor 2 (HER2-targeting imaging probe to visualize differential levels of HER2 expression in a breast cancer model. Specifically, we labeled trastuzumab with Black Hole Quencher 3 (BHQ3 and fluorescein for photoacoustic and fluorescence imaging of HER2 overexpression, respectively. The dual-labeled trastuzumab was tested for its ability to detect HER2 overexpression in vitro and in vivo. We demonstrated an over twofold increase in the signal intensity for HER2-overexpressing tumors in vivo, compared to low–HER2-expressing tumors, using photoacoustic imaging. Furthermore, we demonstrated the feasibility of detecting tumors and positive surgical margins by fluorescence imaging. These results suggest that multimodal HER2-specific imaging of breast cancer using the BHQ3-fluorescein trastuzumab enables molecular-level detection and surgical margin assessment of breast tumors in vivo. This technique may have future clinical impact for primary lesion detection, as well as intraoperative molecular-level surgical guidance in breast cancer.

Comparison of seismic margin assessment and probabilistic risk assessment in seismic IPE

International Nuclear Information System (INIS)

Reed, J.W.; Kassawara, R.P.

1993-01-01

A comparison of technical requirements and managerial issues between seismic margin assessment (SMA) and seismic probabilistic risk assessment (SPRA) in a seismic Individual Plant Examination (IPE) is presented and related to requirements for an Unresolved Safety Issue (USI) A-46 review which is required for older nuclear power plants. Advantages and disadvantages are discussed for each approach. Technical requirements reviewed for a seismic IPE include: scope of plants covered, seismic input, scope of review, selection of equipment, required experience and training of engineers, walkdown procedure, evaluation of components, relay review, containment review, quality assurance, products, documentation requirements, and closure procedure. Managerial issues discussed include regulatory acceptability, compatibility with seismic IPE, compliance with seismic IPE requirements, ease of use by utilities, and relative cost

Consideration of margins for hypo fractionated radiotherapy

International Nuclear Information System (INIS)

Herschtal, A.; Foroudi, F.; Kron, T.

2010-01-01

Full text: Geographical misses of the tumour are of concern in radiotherapy and are typically accommodated by introducing margins around the target. However, there is a trade-off between ensuring the target receives sufficient dose and minimising the dose to surrounding normal structures. Several methods of determining margin width have been developed with the most commonly used one proposed by M. VanHerk (VanHerk UROBP 52: 1407, 2002). VanHerk's model sets margins to achieve 95% of dose coverage for the target in 90% of patients. However, this model was derived assuming an infinite number of fractions. The aim of the present work is to estimate the modifications necessary to the model if a finite number of fractions are given. Software simulations were used to determine the true probability of a patient achieving 95% target coverage if different fraction numbers are used for a given margin width. Model parameters were informed by a large data set recently acquired at our institution using daily image guidance for prostate cancer patients with implanted fiducial markers. Assuming a 3 mm penumbral width it was found that using the VanHerk model only 74 or 54% of patients receive 95% of the prescription dose if 20 or 6 fractions are given, respectively. The steep dose gradients afforded by IMRT are likely to make consideration of the effects of hypofractionation more important. It is necessary to increase the margins around the target to ensure adequate tumour coverage if hypofractionated radiotherapy is to be used for cancer treatment. (author)

Seismic safety margin assessment program (Annual safety research report, JFY 2010)

International Nuclear Information System (INIS)

Suzuki, Kenichi; Iijima, Toru; Inagaki, Masakatsu; Taoka, Hideto; Hidaka, Shinjiro

2011-01-01

Seismic capacity test data, analysis method and evaluation code provided by Seismic Safety Margin Assessment Program have been utilized for the support of seismic back-check evaluation of existing plants. The summary of the program in 2010 is as follows. 1. Component seismic capacity test and quantitative seismic capacity evaluation. Many seismic capacity tests of various snubbers were conducted and quantitative seismic capacities were evaluated. One of the emergency diesel generator partial-model seismic capacity tests was conducted and quantitative seismic capacity was evaluated. Some of the analytical evaluations of piping-system seismic capacities were conducted. 2. Analysis method for minute evaluation of component seismic response. The difference of seismic response of large components such as primary containment vessel and reactor pressure vessel when they were coupled with 3-dimensional FEM building model or 1-dimensional lumped mass building model, was quantitatively evaluated. 3. Evaluation code for quantitative evaluation of seismic safety margin of systems, structures and components. As the example, quantitative evaluation of seismic safety margin of systems, structures and components were conducted for the reference plant. (author)

Pattern of Failure After Limited Margin Radiotherapy and Temozolomide for Glioblastoma

International Nuclear Information System (INIS)

McDonald, Mark W.; Shu, Hui-Kuo G.; Curran, Walter J.; Crocker, Ian R.

2011-01-01

Purpose: To evaluate the pattern of failure after limited margin radiotherapy for glioblastoma. Methods and Materials: We analyzed 62 consecutive patients with newly diagnosed glioblastoma treated between 2006 and 2008 with standard fractionation to a total dose of 60Gy with concurrent temozolomide (97%) or arsenic trioxide (3%). The initial clinical target volume included postoperative T2 abnormality with a median margin of 0.7cm. The boost clinical target volume included residual T1-enhancing tumor and resection cavity with a median margin of 0.5cm. Planning target volumes added a 0.3- or 0.5-cm margin to clinical target volumes. The total boost planning target volume (PTV boost ) margin was 1cm or less in 92% of patients. The volume of recurrent tumor (new T1 enhancement) was categorized by the percent within the 60-Gy isodose line as central (>95%), infield (81-95%), marginal (20-80%), or distant ( boost with a 2.5-cm margin were created for each patient. Results: With a median follow-up of 12 months, radiographic tumor progression developed in 43 of 62 patients. Imaging was available for analysis in 41: 38 (93%) had central or infield failure, 2 (5%) had marginal failure, and 1 (2%) had distant failure relative to the 60-Gy isodose line. The treated PTV boost (median, 140cm 3 ) was, on average, 70% less than the PTV boost with a 2.5-cm margin (median, 477cm 3 ) (p boost margin of 1cm or less did not appear to increase the risk of marginal and/or distant tumor failures compared with other published series. With careful radiation planning and delivery, it appears that treatment margins for glioblastoma can be reduced.

Impact of target reproducibility on tumor dose in stereotactic radiotherapy of targets in the lung and liver.

Science.gov (United States)

Wulf, Jörn; Hädinger, Ulrich; Oppitz, Ulrich; Thiele, Wibke; Flentje, Michael

2003-02-01

Previous analyses of target reproducibility in extracranial stereotactic radiotherapy have revealed standard security margins for planning target volume (PTV) definition of 5mm in axial and 5-10mm in longitudinal direction. In this study the reproducibility of the clinical target volume (CTV) of lung and liver tumors within the PTV over the complete course of hypofractionated treatment is evaluated. The impact of target mobility on dose to the CTV is assessed by dose-volume histograms (DVH). Twenty-two pulmonary and 21 hepatic targets were treated with three stereotactic fractions of 10 Gy to the PTV-enclosing 100%-isodose with normalization to 150% at the isocenter. A conformal dose distribution was related to the PTV, which was defined by margins of 5-10mm added to the CTV. Prior to each fraction a computed tomography (CT)-simulation over the complete target volume was performed resulting in a total of 60 CT-simulations for lung and 58 CT-simulations for hepatic targets. The CTV from each CT-simulation was segmented and matched with the CT-study used for treatment planning. A DVH of the simulated CTV was calculated for each fraction. The target coverage (TC) of dose to the simulated CTV was defined as the proportion of the CTV receiving at least the reference dose (100%). A decrease of TC to or=95% at each fraction of treatment. Pulmonary targets with increased breathing mobility and liver tumors >100 cm(3) are at risk for target deviation exceeding the standard security margins for PTV-definition at least for one fraction and require individual evaluation of sufficient margins.

On-line fatigue monitoring and probabilistic assessment of margins

Energy Technology Data Exchange (ETDEWEB)

Fournier, I. [Electricite de France, 93 - Saint-Denis (France). Direction des Etudes et Recherches; Morilhat, P. [Electricite de France, 93 - Saint-Denis (France). Direction des Etudes et Recherches

1995-01-01

An on-line computer-aided system has been developed by Electricite de France, the French utility, for fatigue monitoring of critical locations in the nuclear steam supply system. This tool, called a fatigue meter, includes as input data plant parameters and is based on some conservative assumptions at several steps of the damage assessment (thermal boundary conditions, stress computation,..). In this paper we present recent developments performed towards a better assessment of margins involved in the complete analysis. The methodology is illustrated with an example showing the influence of uncertainty in plant parameters on the final stress computed at a pressurized water reactor 900MW unit pressurizer surge line nozzle. A second example is shown to illustrate the possibility of defining some transient archetypes. ((orig.)).

Impact of target reproducibility on tumor dose in stereotactic radiotherapy of targets in the lung and liver

International Nuclear Information System (INIS)

Wulf, Joern; Haedinger, Ulrich; Oppitz, Ulrich; Thiele, Wibke; Flentje, Michael

2003-01-01

Background and purpose: Previous analyses of target reproducibility in extracranial stereotactic radiotherapy have revealed standard security margins for planning target volume (PTV) definition of 5 mm in axial and 5-10 mm in longitudinal direction. In this study the reproducibility of the clinical target volume (CTV) of lung and liver tumors within the PTV over the complete course of hypofractionated treatment is evaluated. The impact of target mobility on dose to the CTV is assessed by dose-volume histograms (DVH). Materials and methods: Twenty-two pulmonary and 21 hepatic targets were treated with three stereotactic fractions of 10 Gy to the PTV-enclosing 100%-isodose with normalization to 150% at the isocenter. A conformal dose distribution was related to the PTV, which was defined by margins of 5-10 mm added to the CTV. Prior to each fraction a computed tomography (CT)-simulation over the complete target volume was performed resulting in a total of 60 CT-simulations for lung and 58 CT-simulations for hepatic targets. The CTV from each CT-simulation was segmented and matched with the CT-study used for treatment planning. A DVH of the simulated CTV was calculated for each fraction. The target coverage (TC) of dose to the simulated CTV was defined as the proportion of the CTV receiving at least the reference dose (100%). Results: A decrease of TC to 3 . Conclusions: Target reproducibility was precise within the reference isodose in 91% of lung and 81% of liver tumors with a TC of the complete CTV ≥95% at each fraction of treatment. Pulmonary targets with increased breathing mobility and liver tumors >100 cm 3 are at risk for target deviation exceeding the standard security margins for PTV-definition at least for one fraction and require individual evaluation of sufficient margins

An assessment of seismic margins in nuclear plant piping

International Nuclear Information System (INIS)

Chen, W.P.; Jaquay, K.R.; Chokshi, N.C.; Terao, D.

1995-01-01

Interim results of an ongoing program to assist the U.S. Nuclear Regulatory Commission (NRC) in developing regulatory positions on the seismic analyses of piping and overall safety margins of piping systems are reported. Results of reviews of previous seismic testing, primarily the Electric Power Research Institute (EPRI)/NRC Piping and Fitting Dynamic Reliability Program, and assessments of the ASME Code, Section III, piping seismic design criteria as revised by the 1994 Addenda are reported. Major issues are identified herein only. Technical details are to be provided elsewhere. (author). 4 refs., 2 figs

On probabilistically defined margins in radiation therapy

Energy Technology Data Exchange (ETDEWEB)

Papiez, Lech; Langer, Mark [Department of Radiation Oncology, Indiana University, Indianapolis, IN (United States)

2006-08-21

Margins about a target volume subject to external beam radiation therapy are designed to assure that the target volume of tissue to be sterilized by treatment is adequately covered by a lethal dose. Thus, margins are meant to guarantee that all potential variation in tumour position relative to beams allows the tumour to stay within the margin. Variation in tumour position can be broken into two types of dislocations, reducible and irreducible. Reducible variations in tumour position are those that can be accommodated with the use of modern image-guided techniques that derive parameters for compensating motions of patient bodies and/or motions of beams relative to patient bodies. Irreducible variations in tumour position are those random dislocations of a target that are related to errors intrinsic in the design and performance limitations of the software and hardware, as well as limitations of human perception and decision making. Thus, margins in the era of image-guided treatments will need to accommodate only random errors residual in patient setup accuracy (after image-guided setup corrections) and in the accuracy of systems designed to track moving and deforming tissues of the targeted regions of the patient's body. Therefore, construction of these margins will have to be based on purely statistical data. The characteristics of these data have to be determined through the central limit theorem and Gaussian properties of limiting error distributions. In this paper, we show how statistically determined margins are to be designed in the general case of correlated distributions of position errors in three-dimensional space. In particular, we show how the minimal margins for a given level of statistical confidence are found. Then, how they are to be used to determine geometrically minimal PTV that provides coverage of GTV at the assumed level of statistical confidence. Our results generalize earlier recommendations for statistical, central limit theorem

On probabilistically defined margins in radiation therapy

International Nuclear Information System (INIS)

Papiez, Lech; Langer, Mark

2006-01-01

Margins about a target volume subject to external beam radiation therapy are designed to assure that the target volume of tissue to be sterilized by treatment is adequately covered by a lethal dose. Thus, margins are meant to guarantee that all potential variation in tumour position relative to beams allows the tumour to stay within the margin. Variation in tumour position can be broken into two types of dislocations, reducible and irreducible. Reducible variations in tumour position are those that can be accommodated with the use of modern image-guided techniques that derive parameters for compensating motions of patient bodies and/or motions of beams relative to patient bodies. Irreducible variations in tumour position are those random dislocations of a target that are related to errors intrinsic in the design and performance limitations of the software and hardware, as well as limitations of human perception and decision making. Thus, margins in the era of image-guided treatments will need to accommodate only random errors residual in patient setup accuracy (after image-guided setup corrections) and in the accuracy of systems designed to track moving and deforming tissues of the targeted regions of the patient's body. Therefore, construction of these margins will have to be based on purely statistical data. The characteristics of these data have to be determined through the central limit theorem and Gaussian properties of limiting error distributions. In this paper, we show how statistically determined margins are to be designed in the general case of correlated distributions of position errors in three-dimensional space. In particular, we show how the minimal margins for a given level of statistical confidence are found. Then, how they are to be used to determine geometrically minimal PTV that provides coverage of GTV at the assumed level of statistical confidence. Our results generalize earlier recommendations for statistical, central limit theorem

A Pareto analysis approach to assess relevant marginal CO{sub 2} footprint for petroleum products

Energy Technology Data Exchange (ETDEWEB)

Tehrani, Nejad M. Alireza, E-mail: alireza.tehraninejad@gmail.com

2015-07-15

Recently, linear programing (LP) models have been extended to track the marginal CO{sub 2} intensity of automotive fuels at the refinery gate. The obtained CO{sub 2} data are recommended for policy making because they capture the economic and environmental tensions as well as the processing effects related to oil products. However, they are proven to be extremely sensitive to small perturbations and therefore useless in practice. In this paper, we first investigate the theoretical reasons of this drawback. Then, we develop a multiple objective LP framework to assess relevant marginal CO{sub 2} footprints that preserve both defensibility and stability at a satisfactory level of acceptance. A case study illustrates this new methodology. - Highlights: • Refining LP models have limitations to provide useful marginal CO{sub 2} footprints. • A multi objective optimization framework is developed to assess relevant CO{sub 2} data. • Within a European Refinig industry, diesel is more CO{sub 2} intensive than gasoline.

Use of response envelopes for seismic margin assessment of reinforced concrete walls and slabs

Energy Technology Data Exchange (ETDEWEB)

Ile, Nicolas; Frau, Alberto, E-mail: alberto.frau@cea.fr

2017-04-01

Highlights: • Proposal of a method for application of the elliptical envelope to RC shell elements. • Proposal of new algorithms for the seismic margin evaluation for RC shell elements. • Verification of a RC wall 3D structure, using the proposed assessment approach. - Abstract: Seismic safety evaluations of existing nuclear facilities are usually based on the assumption of structural linearity. For the design basis earthquake (DBE), it is reasonable to apply a conventional evaluation of the seismic safety of building structures and carry out a linear elastic analysis to assess the load effects on structural elements. Estimating the seismic capacity of a structural element requires an estimation of the critical combination of responses acting in this structural element and compare this combination with the capacity of the element. By exploiting the response-spectrum-based procedure for predicting the response envelopes in linear structures formulated by Menun and Der Kiureghian (2000a), algorithms are developed for the seismic margin assessment of reinforced concrete shell finite elements. These algorithms facilitate the comparison of the response-spectrum-based envelopes to prescribed capacity surfaces for the purpose of assessing the safety margin of this kind of structures. The practical application of elliptical response envelopes in case of shell finite elements is based on the use of layer models such as those developed by Marti (1990), which transfer the generalized stress field to three layers under the assumption that the two outer layers carry membrane forces and the internal layer carries only the out-of-plane shears. The utility of the assessment approach is discussed with reference to a case study of a 3D structure made of reinforced concrete walls.

Use of response envelopes for seismic margin assessment of reinforced concrete walls and slabs

International Nuclear Information System (INIS)

Ile, Nicolas; Frau, Alberto

2017-01-01

Highlights: • Proposal of a method for application of the elliptical envelope to RC shell elements. • Proposal of new algorithms for the seismic margin evaluation for RC shell elements. • Verification of a RC wall 3D structure, using the proposed assessment approach. - Abstract: Seismic safety evaluations of existing nuclear facilities are usually based on the assumption of structural linearity. For the design basis earthquake (DBE), it is reasonable to apply a conventional evaluation of the seismic safety of building structures and carry out a linear elastic analysis to assess the load effects on structural elements. Estimating the seismic capacity of a structural element requires an estimation of the critical combination of responses acting in this structural element and compare this combination with the capacity of the element. By exploiting the response-spectrum-based procedure for predicting the response envelopes in linear structures formulated by Menun and Der Kiureghian (2000a), algorithms are developed for the seismic margin assessment of reinforced concrete shell finite elements. These algorithms facilitate the comparison of the response-spectrum-based envelopes to prescribed capacity surfaces for the purpose of assessing the safety margin of this kind of structures. The practical application of elliptical response envelopes in case of shell finite elements is based on the use of layer models such as those developed by Marti (1990), which transfer the generalized stress field to three layers under the assumption that the two outer layers carry membrane forces and the internal layer carries only the out-of-plane shears. The utility of the assessment approach is discussed with reference to a case study of a 3D structure made of reinforced concrete walls.

4D-CT-based target volume definition in stereotactic radiotherapy of lung tumours: Comparison with a conventional technique using individual margins

International Nuclear Information System (INIS)

Hof, Holger; Rhein, Bernhard; Haering, Peter; Kopp-Schneider, Annette; Debus, Juergen; Herfarth, Klaus

2009-01-01

Purpose: To investigate the dosimetric benefit of integration of 4D-CT in the planning target volume (PTV) definition process compared to conventional PTV definition using individual margins in stereotactic body radiotherapy (SBRT) of lung tumours. Material and methods: Two different PTVs were defined: PTV conv consisting of the helical-CT-based clinical target volume (CTV) enlarged isotropically for each spatial direction by the individually measured amount of motion in the 4D-CT, and PTV 4D encompassing the CTVs defined in the 4D-CT phases displaying the extremes of the tumour position. Tumour motion as well as volumetric and dosimetric differences and relations of both PTVs were evaluated. Results: Volumetric examinations revealed a significant reduction of the mean PTV by 4D-CT from 57.7 to 40.7 cm 3 (31%) (p 4D in PTV conv (r = -0.69, 90% confidence limits: -0.87 and -0.34, p = 0.007). Mean lung dose (MLD) was decreased significantly by 17% (p < 0.001). Conclusions: In SBRT of lung tumours the mere use of individual margins for target volume definition cannot compensate for the additional effects that the implementation of 4D-CT phases can offer.

Indigenous women's voices: marginalization and health.

Science.gov (United States)

Dodgson, Joan E; Struthers, Roxanne

2005-10-01

Marginalization may affect health care delivery. Ways in which indigenous women experienced marginalization were examined. Data from 57 indigenous women (18 to 65 years) were analyzed for themes. Three themes emerged: historical trauma as lived marginalization, biculturalism experienced as marginalization, and interacting within a complex health care system. Experienced marginalization reflected participants' unique perspective and were congruent with previous research. It is necessary for health care providers to assess the detrimental impact of marginalization on the health status of individuals and/or communities.

Safety Margin Assessment (SM2A): Stimulation for Further Development of BEPU Approaches?

International Nuclear Information System (INIS)

Zimmermann, Martin A.

2013-01-01

During recent years, many nuclear power plants underwent significant modifications, e.g. power up-rating. While compliance with all the deterministic acceptance criteria must be shown during the licensing process, the larger core inventory and the facts that the plant response might get closer to the limits after a power up-rate, suggest an increase of the core damage frequency (CDF) and other possible risk indicators. Hence, a framework to quantitatively assess a change in plant safety margin becomes very desirable. The Committee on the Safety of Nuclear Installations (CSNI) mandated the Safety Margin Action Plan expert group (SMAP) to develop a framework for the assessment of such changes to safety margin. This framework combines PSA and the analytical techniques developed in BEPU. CSNI then mandated the SM2A expert group to especially explore the practicability of the SMAP framework. This pilot study was completed end of 2010. An increase of the (conditional) probability of exceedance for a surrogate acceptance limit (PCT) indicating core damage was successfully evaluated for the selected sequences from several initiating event trees, and it was found that only a restricted number of sequences need to be analyzed. Based on the insights gained from this study, areas of methodology improvement have been identified and related proposals for further R and D work will be discussed. (authors)

Impact of organ shape variations on margin concepts for cervix cancer ART.

Science.gov (United States)

Seppenwoolde, Yvette; Stock, Markus; Buschmann, Martin; Georg, Dietmar; Bauer-Novotny, Kwei-Yuang; Pötter, Richard; Georg, Petra

2016-09-01

Target and organ movement motivate adaptive radiotherapy for cervix cancer patients. We investigated the dosimetric impact of margin concepts with different levels of complexity on both organ at risk (OAR) sparing and PTV coverage. Weekly CT and daily CBCT scans were delineated for 10 patients. The dosimetric impact of organ shape variations were evaluated for four (isotropic) margin concepts: two static PTVs (PTV 6mm and PTV 15mm ), a PTV based on ITV of the planning CT and CBCTs of the first treatment week (PTV ART ITV ) and an adaptive PTV based on a library approach (PTV ART Library ). Using static concepts, OAR doses increased with large margins, while smaller margins compromised target coverage. ART PTVs resulted in comparable target coverage and better sparing of bladder (V40Gy: 15% and 7% less), rectum (V40Gy: 18 and 6cc less) and bowel (V40Gy: 106 and 15cc less) compared to PTV 15mm . Target coverage evaluation showed that for elective fields a static 5mm margin sufficed. PTV ART Library achieved the best dosimetric results. However when weighing clinical benefit against workload, ITV margins based on repetitive movement evaluation during the first week also provide improvements over static margin concepts. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Methodology for the Assessment of Confidence in Safety Margin for Small Break Loss of Coolant Accident Sequences

Energy Technology Data Exchange (ETDEWEB)

Nagrale, D. B.; Prasad, M.; Rao, R. S.; Gaikwad, A.J., E-mail: avinashg@aerb.gov.in [Nuclear Safety Analysis Division, Atomic Energy Regulatory Board, Mumbai (India)

2014-10-15

Deterministic Safety Analysis and Probabilistic Safety Assessment (PSA) analyses are used concurrently to assess the Nuclear Power Plant (NPP) safety. The conventional deterministic analysis is conservative. The best estimate plus uncertainty analysis is increasingly being used for deterministic calculation in NPPs. The PSA methodology aims to be as realistic as possible while integrating information about accident phenomena, plant design, operating practices, component reliability and human behaviour. The peak clad temperature (PCT) distribution provides an insight into the confidence in safety margin for an initiating event. The paper deals with the concept of calculating the peak clad temperature with 95 percent confidence and 95 percent probability (PCT{sub 95/95}) in small break loss of coolant accident (SBLOCA) and methodologies for assessing safety margin. Five input parameters mainly, nominal power level, decay power, fuel clad gap conductivity, fuel thermal conductivity and discharge coefficient, were selected. A Uniform probability density function was assigned to the uncertain parameters and these uncertainties are propagated using Latin Hypercube Sampling (LHS) technique. The sampled data for 5 parameters were randomly mixed by LHS to obtain 25 input sets. A non-core damage accident sequence was selected from the SBLOCA event tree of a typical VVER study to estimate the PCTs and safety margin. A Kolmogorov– Smirnov goodness-of-fit test was carried out for PCTs. The smallest value of safety margin would indicate the robustness of the system with 95% confidence and 95% probability. Regression analysis was also carried out using 1000 sample size for the estimating PCTs. Mean, variance and finally safety margin were analysed. (author)

How does knowledge of three-dimensional excision margins following breast conservation surgery impact upon clinical target volume definition for partial-breast radiotherapy?

International Nuclear Information System (INIS)

Kirby, Anna M.; Evans, Philip M.; Nerurkar, Ashutosh Y.; Desai, Saral S.; Krupa, Jaroslaw; Devalia, Haresh; Rovere, Guidubaldo Querci della; Harris, Emma J.; Kyriakidou, Julia; Yarnold, John R.

2010-01-01

Background and purpose: To compare partial-breast clinical target volumes generated using a standard 15 mm margin (CTV standard ) with those generated using three-dimensional surgical excision margins (CTV tailored30 ) in women who have undergone wide local excision (WLE) for breast cancer. Material and methods: Thirty-five women underwent WLE with placement of clips in the anterior, deep and coronal excision cavity walls. Distances from tumour to each of six margins were measured microscopically. Tumour bed was defined on kV-CT images using clips. CTV standard was generated by adding a uniform three-dimensional 15 mm margin, and CTV tailored30 was generated by adding 30 mm minus the excision margin in three-dimensions. Concordance between CTV standard and CTV tailored30 was quantified using conformity (CoI), geographical-miss (GMI) and normal-tissue (NTI) indices. An external-beam partial-breast irradiation (PBI) plan was generated to cover 95% of CTV standard with the 95% isodose. Percentage-volume coverage of CTV tailored30 by the 95% isodose was measured. Results: Median (range) coronal, superficial and deep excision margins were 15.0 (0.5-76.0) mm, 4.0 (0.0-60.0) mm and 4.0 (0.5-35.0) mm, respectively. Median CoI, GMI and NTI were 0.62, 0.16 and 0.20, respectively. Median coverage of CTV tailored30 by the PBI-plan was 97.7% (range 84.9-100.0%). CTV tailored30 was inadequately covered by the 95% isodose in 4/29 cases. In three cases, the excision margin in the direction of inadequate coverage was ≤2 mm. Conclusions: CTVs based on 3D excision margin data are discordant with those defined using a standard uniform 15 mm TB-CTV margin. In women with narrow excision margins, the standard TB-CTV margin could result in a geographical miss. Therefore, wider TB-CTV margins should be considered where re-excision does not occur.

The planning target volume margins detected by cone-beam CT in head and neck cancer patients treated by image-guided intensity modulated radiotherapy

International Nuclear Information System (INIS)

Liu Jun; Chen Hong; Zhang Guoqiao; Chen Fei; Zhang Li

2011-01-01

Objective: To determine the planning target volume margins of head and neck cancers treated by image guided radiotherapy (IGRT). Methods: 464 sets cone beam computed tomography (CBCT) images before setup correction and 126 sets CBCT images after correction were obtained from 51 head and neck cancer patients treated by IGRT in our department. The systematic and random errors were evaluated by either online or offline correction through registering the CBCT images to the planning CT. The data was divided into 3 groups according to the online correction times. Results: The isocenter shift were 0.37 mm ± 2.37 mm, -0.43 mm ± 2.30 mm and 0.47 mm ± 2.65 mm in right-left (RL), anterior-posterior (AP) and superior-inferior (SI) directions respectively before correction, and it reduced to 0.08 mm ± 0.68 mm, -0.03 mm ± 0.74 mm and 0.03 mm ± 0.80 mm when evaluated by 126 sets corrected CBCT images. The planning target volume (PTV) margin from clinical target volume (CTV) before correction were: 6.41 mm, 6.15 mm and 7.10 mm based on two parameter model, and it reduced to 1.78 mm, 1.80 mm and 1.97 mm after correction. The PTV margins were 3.8 mm, 3.8 mm, 4.0 mm; 4.0 mm, 4.0 mm, 5.0 mm and 5.4 mm, 5.2 mm, 6.1 mm in RL, AP and SI respectively when online-correction times were more than 15 times, 11-15 times, 5-10 times. Conclusions: CBCT-based on online correction reduce the PTV margin for head and neck cancers treated by IGRT and ensure more precise dose delivery and less normal tissue complications. (authors)

Experimental validation of the van Herk margin formula for lung radiation therapy

International Nuclear Information System (INIS)

Ecclestone, Gillian; Heath, Emily; Bissonnette, Jean-Pierre

2013-01-01

Purpose: To validate the van Herk margin formula for lung radiation therapy using realistic dose calculation algorithms and respiratory motion modeling. The robustness of the margin formula against variations in lesion size, peak-to-peak motion amplitude, tissue density, treatment technique, and plan conformity was assessed, along with the margin formula assumption of a homogeneous dose distribution with perfect plan conformity.Methods: 3DCRT and IMRT lung treatment plans were generated within the ORBIT treatment planning platform (RaySearch Laboratories, Sweden) on 4DCT datasets of virtual phantoms. Random and systematic respiratory motion induced errors were simulated using deformable registration and dose accumulation tools available within ORBIT for simulated cases of varying lesion sizes, peak-to-peak motion amplitudes, tissue densities, and plan conformities. A detailed comparison between the margin formula dose profile model, the planned dose profiles, and penumbra widths was also conducted to test the assumptions of the margin formula. Finally, a correction to account for imperfect plan conformity was tested as well as a novel application of the margin formula that accounts for the patient-specific motion trajectory.Results: The van Herk margin formula ensured full clinical target volume coverage for all 3DCRT and IMRT plans of all conformities with the exception of small lesions in soft tissue. No dosimetric trends with respect to plan technique or lesion size were observed for the systematic and random error simulations. However, accumulated plans showed that plan conformity decreased with increasing tumor motion amplitude. When comparing dose profiles assumed in the margin formula model to the treatment plans, discrepancies in the low dose regions were observed for the random and systematic error simulations. However, the margin formula respected, in all experiments, the 95% dose coverage required for planning target volume (PTV) margin derivation, as

Assessing Mediation Using Marginal Structural Models in the Presence of Confounding and Moderation

Science.gov (United States)

Coffman, Donna L.; Zhong, Wei

2012-01-01

This article presents marginal structural models with inverse propensity weighting (IPW) for assessing mediation. Generally, individuals are not randomly assigned to levels of the mediator. Therefore, confounders of the mediator and outcome may exist that limit causal inferences, a goal of mediation analysis. Either regression adjustment or IPW…

Radiotherapy margin design with particular consideration of high curvature CTVs

International Nuclear Information System (INIS)

Herschtal, Alan; Kron, Tomas; Fox, Chris

2009-01-01

In applying 3D conformal radiation therapy to a tumor clinical target volume (CTV), a margin is added around the CTV to account for any sources of error in the application of treatment which may result in misalignment between the CTV and the dose distribution actually delivered. The volume enclosed within the CTV plus the margin is known as the PTV, or planning target volume. The larger the errors are anticipated to be, the wider the margin will need to be to accommodate those errors. Based on the approach of van Herk et al. [''The probability of correct target dosage: Dose-population histograms for deriving treatment margins in radiotherapy,'' Int. J. Radiat. Oncol. Biol., Phys. 47(4), 1121-1135 (2000)] this paper develops the mathematical theory behind the calculation of the margin width required to ensure that the entire CTV receives sufficiently high dose with sufficiently high probability. The margin recipe developed not only considers the magnitude of the errors but also includes a term to adjust for curved CTV surfaces. In doing so, the accuracy of the margin recipe is enhanced yet remains mathematically concise enough to be readily implemented in the clinical setting. The results are particularly relevant for clinical situations in which the uncertainties in treatment are large relative to the size of the CTV.

Anisotropic Margin Expansions in 6 Anatomic Directions for Oropharyngeal Image Guided Radiation Therapy

International Nuclear Information System (INIS)

Yock, Adam D.; Garden, Adam S.; Court, Laurence E.; Beadle, Beth M.; Zhang, Lifei; Dong, Lei

2013-01-01

Purpose: The purpose of this work was to determine the expansions in 6 anatomic directions that produced optimal margins considering nonrigid setup errors and tissue deformation for patients receiving image-guided radiation therapy (IGRT) of the oropharynx. Methods and Materials: For 20 patients who had received IGRT to the head and neck, we deformably registered each patient's daily images acquired with a computed tomography (CT)-on-rails system to his or her planning CT. By use of the resulting vector fields, the positions of volume elements within the clinical target volume (CTV) (target voxels) or within a 1-cm shell surrounding the CTV (normal tissue voxels) on the planning CT were identified on each daily CT. We generated a total of 15,625 margins by dilating the CTV by 1, 2, 3, 4, or 5 mm in the posterior, anterior, lateral, medial, inferior, and superior directions. The optimal margins were those that minimized the relative volume of normal tissue voxels positioned within the margin while satisfying 1 of 4 geometric target coverage criteria and 1 of 3 population criteria. Results: Each pair of geometric target coverage and population criteria resulted in a unique, anisotropic, optimal margin. The optimal margin expansions ranged in magnitude from 1 to 5 mm depending on the anatomic direction of the expansion and on the geometric target coverage and population criteria. Typically, the expansions were largest in the medial direction, were smallest in the lateral direction, and increased with the demand of the criteria. The anisotropic margin resulting from the optimal set of expansions always included less normal tissue than did any isotropic margin that satisfied the same pair of criteria. Conclusions: We demonstrated the potential of anisotropic margins to reduce normal tissue exposure without compromising target coverage in IGRT to the head and neck

Complete removal of a breast mass by US-guided mammotome biopsy: histologic assessment by marginal sampling

International Nuclear Information System (INIS)

Kim, Youn Jeong; Choi, Hye Young; Moon, Byung In; Lee, Shi Nae

2005-01-01

The aim of this study was to assess whether the complete removal of a breast mass using ultrasound (US) guided mammotome biopsy was successful using a marginal biopsy after insuring the total visual excision of the breast mass on US images. The relationship of complete breast mass removal, and the hematoma, mass size and shape were also evaluated. A US guided mammotome biopsy was performed in a total of 136 cases in 133 patients, with marginal biopsies also added when the complete removal of breast mass had been identified by sonography. The results of the marginal biopsies were serially dividing into three groups, as follows: group I were the cases in the initial 6 months, group II after the initial 6 months and group III having undergone two marginal biopsies. The marginal biopsies were performed in four directions around the probe, with 'marginal positivity' defined as the same histopathological findings to that of the main mass in at least one direction. A statistical analysis was also used to evaluate between the marginal positivity and the hematoma, mass size and shape. The marginal positivities of groups I, II and III were 48.8, 29.4 and 45.5%, respectively. The marginal positivity of those with a lobular shaped mass was significantly higher (ρ = 0.0121) than those with round or oval shaped masses (61.5 vs 33.7 vs 50%), but showed no statistical relationship with hematoma size of the lesions. Although the lesions were removed by US using a US-guided mammotome biopsy, many residual lesions were still histologically present in the marginal samplings, especially in the lobular shaped masse

Thick tissue diffusion model with binding to optimize topical staining in fluorescence breast cancer margin imaging

Science.gov (United States)

Xu, Xiaochun; Kang, Soyoung; Navarro-Comes, Eric; Wang, Yu; Liu, Jonathan T. C.; Tichauer, Kenneth M.

2018-03-01

Intraoperative tumor/surgical margin assessment is required to achieve higher tumor resection rate in breast-conserving surgery. Though current histology provides incomparable accuracy in margin assessment, thin tissue sectioning and the limited field of view of microscopy makes histology too time-consuming for intraoperative applications. If thick tissue, wide-field imaging can provide an acceptable assessment of tumor cells at the surface of resected tissues, an intraoperative protocol can be developed to guide the surgery and provide immediate feedback for surgeons. Topical staining of margins with cancer-targeted molecular imaging agents has the potential to provide the sensitivity needed to see microscopic cancer on a wide-field image; however, diffusion and nonspecific retention of imaging agents in thick tissue can significantly diminish tumor contrast with conventional methods. Here, we present a mathematical model to accurately simulate nonspecific retention, binding, and diffusion of imaging agents in thick tissue topical staining to guide and optimize future thick tissue staining and imaging protocol. In order to verify the accuracy and applicability of the model, diffusion profiles of cancer targeted and untargeted (control) nanoparticles at different staining times in A431 tumor xenografts were acquired for model comparison and tuning. The initial findings suggest the existence of nonspecific retention in the tissue, especially at the tissue surface. The simulator can be used to compare the effect of nonspecific retention, receptor binding and diffusion under various conditions (tissue type, imaging agent) and provides optimal staining and imaging protocols for targeted and control imaging agent.

Seismic margin assessment of spanish nuclear power plants: a perspective from industry and regulators

International Nuclear Information System (INIS)

Garcia-Monge, Juan; Beltran, Francisco; Sanchez-Cabanero, Jose G.

2001-01-01

The worldwide experience with probabilistic safety analysis (PSA) of nuclear power plants shows that the risk derived from earthquakes can be a significant contributor to core damage frequency in some instances. As a consequence, no severe accident safety assessment can be considered complete without giving, due consideration to seismic risk. This fact has been recognized by some regulators. in particular, by the U.S. Nuclear Regulatory Commission (NRC), who has included seismic risk assessment in its severe accident policy. The NRC severe accident policy was adopted by the Spanish nuclear regulator. the Consejo de Seguridad Nuclear (CSN). As a result. all plants in Spain were asked to perform a seismic risk analysis according to Supplements No. 4 and 5 of Generic Letter 88-20 and NUREG-1407, which included the containment failure analysis. At present in Spain there arc nine operating reactors at seven sites: six Westinghouse-PWR, two GE-BWR and one Siemens/KW U-PWR. The vintages are very different: the oldest plant started commercial operation in 1968 and the most recent, in 1988. In this framework, the Spanish Owners Group (SOG) proposed to CSN in 1994 to carry out the seismic risk analysis of the plants using seismic margin methodologies. This kind of methods requires, as a starting point, the definition of a seismic margin earthquake (SNIE), also called review level earthquake (RLL). For this purpose, tile SOG sponsored a general Probabilistic Seismic Hazard Analysis (PSHA) for the seven Spanish sites. The results of this PSHA were used by the SOG to define tile RLE and the scope of the study for each plant (binning of plants). The proposal was submitted to the CSN for evaluation. The CSN evaluation was based on the NRC practical experience and was helped by the technical advise of US Lawrence Livermore National Laboratory. The review showed that the uncertainties on seismic hazard had not been fully captured and that it would have been justified to consider a

A new assessment method for demonstrating the sufficiency of the safety assessment and the safety margins of the geological disposal system

International Nuclear Information System (INIS)

Ohi, Takao; Kawasaki, Daisuke; Chiba, Tamotsu; Takase, Toshio; Hane, Koji

2013-01-01

A new method for demonstrating the sufficiency of the safety assessment and safety margins of the geological disposal system has been developed. The method is based on an existing comprehensive sensitivity analysis method and can systematically identify the successful conditions, under which the dose rate does not exceed specified safety criteria, using analytical solutions for nuclide migration and the results of a statistical analysis. The successful conditions were identified using three major variables. Furthermore, the successful conditions at the level of factors or parameters were obtained using relational equations between the variables and the factors or parameters making up these variables. In this study, the method was applied to the safety assessment of the geological disposal of transuranic waste in Japan. Based on the system response characteristics obtained from analytical solutions and on the successful conditions, the classification of the analytical conditions, the sufficiency of the safety assessment and the safety margins of the disposal system were then demonstrated. A new assessment procedure incorporating this method into the existing safety assessment approach is proposed in this study. Using this procedure, it is possible to conduct a series of safety assessment activities in a logical manner. (author)

Economic assessment of Operational Energy reduction options in a house using Marginal Benefit and Marginal Cost: A case in Bangi, Malaysia

International Nuclear Information System (INIS)

Wan Rahmah Mohd Zaki; Abdul Hadi Nawawi; Sabarinah Sh Ahmad

2010-01-01

Energy Efficient (EE) appliances such as Compact Fluorescent Light (CFL) bulbs and Renewable Energy (RE), namely solar Photovoltaic (PV) can help to reduce Operational Energy (OE) in a house. In addition, a house should also incorporate Passive Architecture (PA) design strategies which in the hot and humid tropical climate, mean avoiding direct heat gain, encouraging natural cross ventilation and optimising the abundant daylight. Nevertheless, reducing OE must also mean economic gain to households to encourage their participation. Common economic gauges such as Return on Investment, Payback Period, Cost Benefit Analysis, Life Cycle Assessment and Life Cycle Cost are not suitable to validate OE options in households. These economic gauges approach economic assessment as an end-result on the cost side of the product and may result for good intention to be shelved, primarily because EE equipment and RE have high capital cost compared with the alternatives. On the other hand, reducing OE in houses is actually a continual progression from the status quo and there is always a marginal gain in doing so. The challenge is to know how much is the marginal benefit against the marginal cost of investing in EE and RE. In Economics, the ratio of Marginal Cost (MC) and Marginal Benefits (MB) measure additional benefits of every additional costs of investment at a specific level of production and consumption; and Economists suggests that effective gain and loss should be compared to the status quo, i.e., Relative Position (RP). The Economics theories of MC, MB and RP are being adapted to measure the progression of reducing OE. The living/dining area in two types of houses: with and without PA design strategies are simulated to use conventional incandescent light bulbs and CFL as well as solar PV in lieu of the mains electricity supply. The power requirement for artificial lighting in every case is translated into monetary value and the ratio of MB against MC for each case shows

NRC Seismic Design Margins Program Plan

International Nuclear Information System (INIS)

Cummings, G.E.; Johnson, J.J.; Budnitz, R.J.

1985-08-01

Recent studies estimate that seismically induced core melt comes mainly from earthquakes in the peak ground acceleration range from 2 to 4 times the safe shutdown earthquake (SSE) acceleration used in plant design. However, from the licensing perspective of the US Nuclear Regulatory Commission, there is a continuing need for consideration of the inherent quantitative seismic margins because of, among other things, the changing perceptions of the seismic hazard. This paper discusses a Seismic Design Margins Program Plan, developed under the auspices of the US NRC, that provides the technical basis for assessing the significance of design margins in terms of overall plant safety. The Plan will also identify potential weaknesses that might have to be addressed, and will recommend technical methods for assessing margins at existing plants. For the purposes of this program, a general definition of seismic design margin is expressed in terms of how much larger that the design basis earthquake an earthquake must be to compromise plant safety. In this context, margin needs to be determined at the plant, system/function, structure, and component levels. 14 refs., 1 fig

Marginal Generation Technology in the Chinese Power Market towards 2030 Based on Consequential Life Cycle Assessment

Directory of Open Access Journals (Sweden)

Guangling Zhao

2016-09-01

Full Text Available Electricity consumption is often the hotspot of life cycle assessment (LCA of products, industrial activities, or services. The objective of this paper is to provide a consistent, scientific, region-specific electricity-supply-based inventory of electricity generation technology for national and regional power grids. Marginal electricity generation technology is pivotal in assessing impacts related to additional consumption of electricity. China covers a large geographical area with regional supply grids; these are arguably equally or less integrated. Meanwhile, it is also a country with internal imbalances in regional energy supply and demand. Therefore, we suggest an approach to achieve a geographical subdivision of the Chinese electricity grid, corresponding to the interprovincial regional power grids, namely the North, the Northeast, the East, the Central, the Northwest, and the Southwest China Grids, and the China Southern Power Grid. The approach combines information from the Chinese national plans on for capacity changes in both production and distribution grids, and knowledge of resource availability. The results show that nationally, marginal technology is coal-fired electricity generation, which is the same scenario in the North and Northwest China Grid. In the Northeast, East, and Central China Grid, nuclear power gradually replaces coal-fired electricity and becomes the marginal technology. In the Southwest China Grid and the China Southern Power Grid, the marginal electricity is hydropower towards 2030.

CRBRP structural and thermal margin beyond the design base

International Nuclear Information System (INIS)

Strawbridge, L.E.

1979-01-01

Prudent margins beyond the design base have been included in the design of Clinch River Breeder Reactor Plant to further reduce the risk to the public from highly improbable occurrences. These margins include Structural Margin Beyond the Design Base to address the energetics aspects and Thermal Margin Beyond the Design Base to address the longer term thermal and radiological consequences. The assessments that led to the specification of these margins are described, along with the experimental support for those assessments. 8 refs

Intra-fractional bladder motion and margins in adaptive radiotherapy for urinary bladder cancer

DEFF Research Database (Denmark)

Grønborg, Caroline; Vestergaard, Anne; Høyer, Morten

2015-01-01

and to estimate population-based and patient-specific intra-fractional margins, also relevant for a future re-optimisation strategy. MATERIAL AND METHODS: Nine patients treated in a clinical phase II ART trial of daily plan selection for bladder cancer were included. In the library plans, 5 mm isotropic margins......BACKGROUND: The bladder is a tumour site well suited for adaptive radiotherapy (ART) due to large inter-fractional changes, but it also displays considerable intra-fractional motion. The aim of this study was to assess target coverage with a clinically applied method for plan selection ART...... were added to account for intra-fractional changes. Pre-treatment and weekly repeat magnetic resonance imaging (MRI) series were acquired in which a full three-dimensional (3D) volume was scanned every second min for 10 min (a total of 366 scans in 61 series). Initially, the bladder clinical target...

Life Cycle Assessment of Bioenergy from Lignocellulosic Crops Cultivated on Marginal Land in Europe

Science.gov (United States)

Rettenmaier, Nils; Schmidt, Tobias; Gärtner, Sven; Reinhardt, Guido

2017-04-01

Population growth and changing diets due to economic development lead to an additional demand for land for food and feed production. Slowly but surely turning into a mass market, also the cultivation of non-food biomass crops for fibre (bio-based products) and fuel (biofuels and bioenergy) is increasingly contributing to the pressure on global agricultural land. As a consequence, the already prevailing competition for land might even intensify over the next decades. Against this background, the possibilities of shifting the cultivation of non-food biomass crops to so-called 'marginal lands' are investigated. The EC-funded project 'Sustainable exploitation of biomass for bioenergy from marginal lands in Europe' (SEEMLA) aims at the establishment of suitable innovative land-use strategies for a sustainable production of bioenergy from lignocellulosic crops on marginal lands while improving general ecosystem services. For a complete understanding of the environmental benefits and drawbacks of the envisioned cultivation of bioenergy crops on marginal land, life cycle assessments (LCA) have proven to be a suitable and valuable tool. Thus, embedded into a comprehensive sustainability assessment, a screening LCA is carried out for the entire life cycles of the bioenergy carriers researched in SEEMLA. Investigated systems, on the one hand, include the specific field trials carried out by the SEEMLA partners in Ukraine, Greece and Germany. On the other hand, generic scenarios are investigated in order to derive reliable general statements on the environmental impacts of bioenergy from marginal lands in Europe. Investigated crops include woody and herbaceous species such as black locust, poplar, pine, willow and Miscanthus. Conversion technologies cover the use in a domestic or a district heating plant, power plant, CHP as well as the production of Fischer-Tropsch diesel (FT diesel) and lignocellulosic ethanol. Environmental impacts are compared to conventional reference

Margins for treatment planning of proton therapy

International Nuclear Information System (INIS)

Thomas, Simon J

2006-01-01

For protons and other charged particles, the effect of set-up errors on the position of isodoses is considerably less in the direction of the incident beam than it is laterally. Therefore, the margins required between the clinical target volume (CTV) and planning target volume (PTV) can be less in the direction of the incident beam than laterally. Margins have been calculated for a typical head plan and a typical prostate plan, for a single field, a parallel opposed and a four-field arrangement of protons, and compared with margins calculated for photons, assuming identical geometrical uncertainties for each modality. In the head plan, where internal motion was assumed negligible, the CTV-PTV margin reduced from approximately 10 mm to 3 mm in the axial direction for the single field and parallel opposed plans. For a prostate plan, where internal motion cannot be ignored, the corresponding reduction in margin was from 11 mm to 7 mm. The planning organ at risk (PRV) margin in the axial direction reduced from 6 mm to 2 mm for the head plan, and from 7 mm to 4 mm for the prostate plan. No reduction was seen on the other axes, or for any axis of the four-field plans. Owing to the shape of proton dose distributions, there are many clinical cases in which good dose distributions can be obtained with one or two fields. When this is done, it is possible to use smaller PTV and PRV margins. This has the potential to convert untreatable cases, in which the PTV and PRV overlap, into cases with a gap between PTV and PRV of adequate size for treatment planning

SU-F-J-17: Patient Localization Using MRI-Guided Soft Tissue for Head-And-Neck Radiotherapy: Indication for Margin Reduction and Its Feasibility

International Nuclear Information System (INIS)

Qi, X; Yang, Y; Jack, N; Santhanam, A; Yang, L; Chen, A; Low, D

2016-01-01

Purpose: On-board MRI provides superior soft-tissue contrast, allowing patient alignment using tumor or nearby critical structures. This study aims to study H&N MRI-guided IGRT to analyze inter-fraction patient setup variations using soft-tissue targets and design appropriate CTV-to-PTV margin and clinical implication. Methods: 282 MR images for 10 H&N IMRT patients treated on a ViewRay system were retrospectively analyzed. Patients were immobilized using a thermoplastic mask on a customized headrest fitted in a radiofrequency coil and positioned to soft-tissue targets. The inter-fraction patient displacements were recorded to compute the PTV margins using the recipe: 2.5∑+0.7σ. New IMRT plans optimized on the revised PTVs were generated to evaluate the delivered dose distributions. An in-house dose deformation registration tool was used to assess the resulting dosimetric consequences when margin adaption is performed based on weekly MR images. The cumulative doses were compared to the reduced margin plans for targets and critical structures. Results: The inter-fraction displacements (and standard deviations), ∑ and σ were tabulated for MRI and compared to kVCBCT. The computed CTV-to-PTV margin was 3.5mm for soft-tissue based registration. There were minimal differences between the planned and delivered doses when comparing clinical and the PTV reduced margin plans: the paired t-tests yielded p=0.38 and 0.66 between the planned and delivered doses for the adapted margin plans for the maximum cord and mean parotid dose, respectively. Target V95 received comparable doses as planned for the reduced margin plans. Conclusion: The 0.35T MRI offers acceptable soft-tissue contrast and good spatial resolution for patient alignment and target visualization. Better tumor conspicuity from MRI allows soft-tissue based alignments with potentially improved accuracy, suggesting a benefit of margin reduction for H&N radiotherapy. The reduced margin plans (i.e., 2 mm) resulted

Recommendations for CTV margins in radiotherapy planning for non melanoma skin cancer.

Science.gov (United States)

Khan, Luluel; Choo, Richard; Breen, Dale; Assaad, Dalal; Fialkov, Jefferey; Antonyshyn, Oleh; McKenzie, David; Woo, Tony; Zhang, Liying; Barnes, Elizabeth

2012-08-01

To provide practice guidelines for delineating clinical target volume (CTV) for radiotherapy planning of non melanoma (NMSC) skin cancers. A prospective, single arm, study. Preoperatively, a radiation oncologist outlined the boundary of a gross lesion, and drew 5-mm incremental marks in four directions from the delineated border. Under local anesthesia, the lesion was excised, and resection margins were assessed microscopically by frozen section. Once resection margins were clear, the microscopic tumor extent was calculated using the presurgical incremental markings as references. A potential relationship between the distance of microscopic tumor extension and other variables was analyzed. A total of 159 lesions in 150 consecutive patients, selected for surgical excision with frozen section assisted assessment of resection margins, were accrued. The distance of microscopic tumor extension beyond a gross lesion varied from 1mm to 15 mm, with a mean of 5.3mm. The microscopic tumor extent was positively correlated with the size of gross lesion, histology and number of surgical attempts required to obtain a clear margin. To provide a 95% or greater chance of covering microscopic disease we make the following recommendations for CTV margins; 10mm for BCC less than 2 cm, 13 mm for BCC greater than 2 cm, 11 mm for SCC less than 2 cm, and 14 mm for SCC greater than 2 cm. Tumors greater than 2 cm and SCC histology required larger margins to adequately cover the microscopic extent of disease. This information is crucial in radiation planning of NMSC. Clinicians should be cautioned, as these guidelines may not offer optimum treatment for patients with extremely large or small lesions. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Recommendations for CTV margins in radiotherapy planning for non melanoma skin cancer

International Nuclear Information System (INIS)

Khan, Luluel; Choo, Richard; Breen, Dale; Assaad, Dalal; Fialkov, Jefferey; Antonyshyn, Oleh; McKenzie, David; Woo, Tony; Zhang Liying; Barnes, Elizabeth

2012-01-01

Purpose: To provide practice guidelines for delineating clinical target volume (CTV) for radiotherapy planning of non melanoma (NMSC) skin cancers. Methods and materials: A prospective, single arm, study. Preoperatively, a radiation oncologist outlined the boundary of a gross lesion, and drew 5-mm incremental marks in four directions from the delineated border. Under local anesthesia, the lesion was excised, and resection margins were assessed microscopically by frozen section. Once resection margins were clear, the microscopic tumor extent was calculated using the presurgical incremental markings as references. A potential relationship between the distance of microscopic tumor extension and other variables was analyzed. Results: A total of 159 lesions in 150 consecutive patients, selected for surgical excision with frozen section assisted assessment of resection margins, were accrued. The distance of microscopic tumor extension beyond a gross lesion varied from 1 mm to 15 mm, with a mean of 5.3 mm. The microscopic tumor extent was positively correlated with the size of gross lesion, histology and number of surgical attempts required to obtain a clear margin. To provide a 95% or greater chance of covering microscopic disease we make the following recommendations for CTV margins; 10 mm for BCC less than 2 cm, 13 mm for BCC greater than 2 cm, 11 mm for SCC less than 2 cm, and 14 mm for SCC greater than 2 cm. Conclusions: Tumors greater than 2 cm and SCC histology required larger margins to adequately cover the microscopic extent of disease. This information is crucial in radiation planning of NMSC. Clinicians should be cautioned, as these guidelines may not offer optimum treatment for patients with extremely large or small lesions.

Circumferential resection margin (CRM) positivity after MRI assessment and adjuvant treatment in 189 patients undergoing rectal cancer resection.

Science.gov (United States)

Simpson, G S; Eardley, N; McNicol, F; Healey, P; Hughes, M; Rooney, P S

2014-05-01

The management of rectal cancer relies on accurate MRI staging. Multi-modal treatments can downstage rectal cancer prior to surgery and may have an effect on MRI accuracy. We aim to correlate the findings of MRI staging of rectal cancer with histological analysis, the effect of neoadjuvant therapy on this and the implications of circumferential resection margin (CRM) positivity following neoadjuvant therapy. An analysis of histological data and radiological staging of all cases of rectal cancer in a single centre between 2006 and 2011 were conducted. Two hundred forty-one patients had histologically proved rectal cancer during the study period. One hundred eighty-two patients underwent resection. Median age was 66.6 years, and male to female ratio was 13:5. R1 resection rate was 11.1%. MRI assessments of the circumferential resection margin in patients without neoadjuvant radiotherapy were 93.6 and 88.1% in patients who underwent neoadjuvant radiotherapy. Eighteen patients had predicted positive margins following chemoradiotherapy, of which 38.9% had an involved CRM on histological analysis. MRI assessment of the circumferential resection margin in rectal cancer is associated with high accuracy. Neoadjuvant chemoradiotherapy has a detrimental effect on this accuracy, although accuracy remains high. In the presence of persistently predicted positive margins, complete resection remains achievable but may necessitate a more radical approach to resection.

Methylation patterns in marginal zone lymphoma.

Science.gov (United States)

Arribas, Alberto J; Bertoni, Francesco

Promoter DNA methylation is a major regulator of gene expression and transcription. The identification of methylation changes is important for understanding disease pathogenesis, for identifying prognostic markers and can drive novel therapeutic approaches. In this review we summarize the current knowledge regarding DNA methylation in MALT lymphoma, splenic marginal zone lymphoma, nodal marginal zone lymphoma. Despite important differences in the study design for different publications and the existence of a sole large and genome-wide methylation study for splenic marginal zone lymphoma, it is clear that DNA methylation plays an important role in marginal zone lymphomas, in which it contributes to the inactivation of tumor suppressors but also to the expression of genes sustaining tumor cell survival and proliferation. Existing preclinical data provide the rationale to target the methylation machinery in these disorders. Copyright © 2016 Elsevier Ltd. All rights reserved.

Correlation of breast tissue histology and optical signatures to improve margin assessment techniques

Science.gov (United States)

Kennedy, Stephanie; Caldwell, Matthew; Bydlon, Torre; Mulvey, Christine; Mueller, Jenna; Wilke, Lee; Barry, William; Ramanujam, Nimmi; Geradts, Joseph

2016-06-01

Optical spectroscopy is sensitive to morphological composition and has potential applications in intraoperative margin assessment. Here, we evaluate ex vivo breast tissue and corresponding quantified hematoxylin & eosin images to correlate optical scattering signatures to tissue composition stratified by patient characteristics. Adipose sites (213) were characterized by their cell area and density. All other benign and malignant sites (181) were quantified using a grid method to determine composition. The relationships between mean reduced scattering coefficient (), and % adipose, % collagen, % glands, adipocyte cell area, and adipocyte density were investigated. These relationships were further stratified by age, menopausal status, body mass index (BMI), and breast density. We identified a positive correlation between and % collagen and a negative correlation between and age and BMI. Increased collagen corresponded to increased variability. In postmenopausal women, was similar regardless of fibroglandular content. Contributions from collagen and glands to were independent and equivalent in benign sites; glands showed a stronger positive correlation than collagen to in malignant sites. Our data suggest that scattering could differentiate highly scattering malignant from benign tissues in postmenopausal women. The relationship between scattering and tissue composition will support improved scattering models and technologies to enhance intraoperative optical margin assessment.

Calculating radiotherapy margins based on Bayesian modelling of patient specific random errors

International Nuclear Information System (INIS)

Herschtal, A; Te Marvelde, L; Mengersen, K; Foroudi, F; Ball, D; Devereux, T; Pham, D; Greer, P B; Pichler, P; Eade, T; Kneebone, A; Bell, L; Caine, H; Hindson, B; Kron, T; Hosseinifard, Z

2015-01-01

Collected real-life clinical target volume (CTV) displacement data show that some patients undergoing external beam radiotherapy (EBRT) demonstrate significantly more fraction-to-fraction variability in their displacement (‘random error’) than others. This contrasts with the common assumption made by historical recipes for margin estimation for EBRT, that the random error is constant across patients. In this work we present statistical models of CTV displacements in which random errors are characterised by an inverse gamma (IG) distribution in order to assess the impact of random error variability on CTV-to-PTV margin widths, for eight real world patient cohorts from four institutions, and for different sites of malignancy. We considered a variety of clinical treatment requirements and penumbral widths. The eight cohorts consisted of a total of 874 patients and 27 391 treatment sessions. Compared to a traditional margin recipe that assumes constant random errors across patients, for a typical 4 mm penumbral width, the IG based margin model mandates that in order to satisfy the common clinical requirement that 90% of patients receive at least 95% of prescribed RT dose to the entire CTV, margins be increased by a median of 10% (range over the eight cohorts −19% to +35%). This substantially reduces the proportion of patients for whom margins are too small to satisfy clinical requirements. (paper)

Impact of Millimeter-Level Margins on Peripheral Normal Brain Sparing for Gamma Knife Radiosurgery

International Nuclear Information System (INIS)

Ma, Lijun; Sahgal, Arjun; Larson, David A.; Pinnaduwage, Dilini; Fogh, Shannon; Barani, Igor; Nakamura, Jean; McDermott, Michael; Sneed, Penny

2014-01-01

Purpose: To investigate how millimeter-level margins beyond the gross tumor volume (GTV) impact peripheral normal brain tissue sparing for Gamma Knife radiosurgery. Methods and Materials: A mathematical formula was derived to predict the peripheral isodose volume, such as the 12-Gy isodose volume, with increasing margins by millimeters. The empirical parameters of the formula were derived from a cohort of brain tumor and surgical tumor resection cavity cases (n=15) treated with the Gamma Knife Perfexion. This was done by first adding margins from 0.5 to 3.0 mm to each individual target and then creating for each expanded target a series of treatment plans of nearly identical quality as the original plan. Finally, the formula was integrated with a published logistic regression model to estimate the treatment-induced complication rate for stereotactic radiosurgery when millimeter-level margins are added. Results: Confirmatory correlation between the nominal target radius (ie, R T ) and commonly used maximum target size was found for the studied cases, except for a few outliers. The peripheral isodose volume such as the 12-Gy volume was found to increase exponentially with increasing Δ/R T , where Δ is the margin size. Such a curve fitted the data (logarithmic regression, R 2 >0.99), and the 12-Gy isodose volume was shown to increase steeply with a 0.5- to 3.0-mm margin applied to a target. For example, a 2-mm margin on average resulted in an increase of 55% ± 16% in the 12-Gy volume; this corresponded to an increase in the symptomatic necrosis rate of 6% to 25%, depending on the Δ/R T values for the target. Conclusions: Millimeter-level margins beyond the GTV significantly impact peripheral normal brain sparing and should be applied with caution. Our model provides a rapid estimate of such an effect, particularly for large and/or irregularly shaped targets

Assessment of ablative margin after radiofrequency ablation for hepatocellular carcinoma; comparison between magnetic resonance imaging with ferucarbotran and enhanced CT with iodized oil deposition

International Nuclear Information System (INIS)

Koda, Masahiko; Tokunaga, Shiho; Fujise, Yuki; Kato, Jun; Matono, Tomomitsu; Sugihara, Takaaki; Nagahara, Takakazu; Ueki, Masaru; Murawaki, Yoshikazu; Kakite, Suguru; Yamashita, Eijiro

2012-01-01

Background and purpose: Our aim was to investigate whether magnetic resonance imaging (MRI) with ferucarbotran administered prior to radiofrequency ablation could accurately assess ablative margin when compared with enhanced computed tomography (CT) with iodized oil marking. Materials and methods: We enrolled 27 patients with 32 hepatocellular carcinomas in which iodized oil deposits were visible throughout the nodule after transcatheter arterial chemoembolization. For these nodules, radiofrequency ablation was performed after ferucarbotran administration. We then performed T2-weighted MRI after 1 week and enhanced CT after 1 month. T2-weighted MRI demonstrated the ablative margin as a low-intensity rim. We classified the margin into three grades; margin (+): high-intensity area with a continuous low-intensity rim; margin zero: high-intensity area with a discontinuous low-intensity rim; and margin (−): high-intensity area extending beyond the low-intensity rim. Results: In 28 (86%) of 32 nodules, there was agreement between MRI and CT. The overall agreement between for the two modalities in the assessment of ablative margin was good (κ = 0.759, 95% confidence interval: 0.480–1.000, p < 0.001). In four nodules, ablative margins on MRI were underestimated by one grade compared with CT. Conclusion: MRI using ferucarbotran is less invasive and allows earlier assessment than CT. The MRI technique performed similarly to enhanced CT with iodized oil marking in evaluating the ablative margin after radiofrequency ablation.

Assessment of unhealthy days of urban marginal inhabitants and effective factors in Mashhad, Iran

Directory of Open Access Journals (Sweden)

Maliheh Ziaee

2016-01-01

Full Text Available Background: The concept of the quality of life (HRQOL related to health and its determinants contain aspects of quality of life that clearly affect people’s physical or mental health. One of the newest ways to assess the health and also the quality of life-related to health is the self-assessed health of the individual. The aim of the present study was assessment of unhealthy days, self-reported health status, and its influencing factors on residents of the marginalpart of Mashhad, Iran. Methods: In the current cross-sectional study, 580 citizens of the marginal regions and slum areas of Mashhad city were enrolled through cluster sampling method using governmental health care services divisions. The Persian version of the questionnaire CDC HRQOL-4 was used to measure the unhealthy days. Data was analyzed using SPSS, version 11.5, running ANOVA, chi-square, and t-tests. P-value of less than 0.05 was considered as statistically significant. Results: In the present study, 359 persons (61% were women and the mean age of participants was 32.6±11.51 years. The means of unhealthy days, physically unhealthy days, mentally unhealthy days, and days with dysfunction were found to be 7.2, 2.8, 4.1, and 1.7 days, respectively. The unhealthiest days (physical and mental were seen in unemployed people and the best to excellent health days were seen in housewives. Conclusion: Unhealthy days and days with dysfunction were reported higher in slum inhabitants, especially female, low literacy, and housewife participants. Providing the education and employment facilities for people who live in marginal city areas might decrease the unhealthy days.Keywords: Unhealthy days; Health; Urban Marginal Inhabitants; Mashhad

The value of breast lumpectomy margin assessment as a predictor of residual tumor burden

International Nuclear Information System (INIS)

Wazer, David E.; Schmidt-Ullrich, Rupert K.; Schmid, Christopher H.; Ruthazer, Robin; Kramer, Bradley; Safaii, Homa; Graham, Roger

1997-01-01

Purpose: Margin assessment is commonly used as a guide to the relative aggressiveness of therapy for breast conserving treatment (BCT), though its value as a predictor of the presence, type, or extent of residual tumor has not been conclusively studied. Controversy continues to exist as to what constitutes a margin that is 'positive', 'close', or 'negative'. We attempt to address these issues through an analysis of re-excision specimens. Patients and Methods: As part of an institutional prospective practice approach for BCT, 265 cases with AJCC Stage I/II carcinoma with an initial excision margin that was ≤2 mm or indeterminate were subjected to re-excision. The probability of residual tumor (+RE) was evaluated with respect to tumor size, histopathologic subtype, relative closeness of the measured margin, the extent of margin positivity graded as focal, minimal, moderate, or extensive, and the extent of specimen processing as reflected in the number of cut sections per specimen volume (S:V ratio). The amount of residual tumor was graded as microscopic, small, medium, or large. The histopathologic subtype of tumor in the re-excision specimen was classified as having an invasive component (ICa) or pure DCIS (DCIS). Results: The primary excision margin was positive, >0≤1 mm, 1.1-2 mm, and indeterminate in 60%, 18%, 5%, and 17%, respectively. The predominant histopathologies in the initial excision specimens were invasive ductal (IDC) (50%) and tumors with an extensive intraductal component (EIC) (43%). The histopathology of the initial excision specimen was highly predictive of the histopathology of tumor found on re-excision, as residual DCIS was found in 60% of +RE specimens with initial histopathology of EIC compared to 26% for IDC (p 0.001). Neither the extent of margin positivity nor the extent of tumor in the re-excision were significantly related to the initial histopathologic subtype; however, a +RE was seen in 59% of EIC, 43% of IDC, and 32% of invasive

Quantifying motion for pancreatic radiotherapy margin calculation

International Nuclear Information System (INIS)

Whitfield, Gillian; Jain, Pooja; Green, Melanie; Watkins, Gillian; Henry, Ann; Stratford, Julie; Amer, Ali; Marchant, Thomas; Moore, Christopher; Price, Patricia

2012-01-01

Background and purpose: Pancreatic radiotherapy (RT) is limited by uncertain target motion. We quantified 3D patient/organ motion during pancreatic RT and calculated required treatment margins. Materials and methods: Cone-beam computed tomography (CBCT) and orthogonal fluoroscopy images were acquired post-RT delivery from 13 patients with locally advanced pancreatic cancer. Bony setup errors were calculated from CBCT. Inter- and intra-fraction fiducial (clip/seed/stent) motion was determined from CBCT projections and orthogonal fluoroscopy. Results: Using an off-line CBCT correction protocol, systematic (random) setup errors were 2.4 (3.2), 2.0 (1.7) and 3.2 (3.6) mm laterally (left–right), vertically (anterior–posterior) and longitudinally (cranio-caudal), respectively. Fiducial motion varied substantially. Random inter-fractional changes in mean fiducial position were 2.0, 1.6 and 2.6 mm; 95% of intra-fractional peak-to-peak fiducial motion was up to 6.7, 10.1 and 20.6 mm, respectively. Calculated clinical to planning target volume (CTV–PTV) margins were 1.4 cm laterally, 1.4 cm vertically and 3.0 cm longitudinally for 3D conformal RT, reduced to 0.9, 1.0 and 1.8 cm, respectively, if using 4D planning and online setup correction. Conclusions: Commonly used CTV–PTV margins may inadequately account for target motion during pancreatic RT. Our results indicate better immobilisation, individualised allowance for respiratory motion, online setup error correction and 4D planning would improve targeting.

Safety assessment of a lithium target

International Nuclear Information System (INIS)

Burgazzi, Luciano; Roberta, Ferri; Barbara, Giannone

2006-01-01

This paper addresses the safety assessment of the lithium target of the International Fusion Materials Irradiation Facility (IFMIF) through evaluating the most important risk factors related to system operation and verifying the fulfillment of the safety criteria. The hazard assessment is based on using a well-structured Failure Mode and Effect Analysis (FMEA) procedure by detailing on a component-by-component basis all the possible failure modes and identifying their effects on the plant. Additionally, a systems analysis, applying the fault tree technique, is performed in order to evaluate, from a probabilistic standpoint, all the relevant and possible failures of each component required for safe system operation and assessing the unavailability of the lithium target system. The last task includes the thermal-hydraulic transient analysis of the target lithium loop, including operational and accident transients. A lithium target loop model is developed, using the RELAP5/Mod3.2 thermal-hydraulic code, which has been modified to include specific features of IFMIF itself. The main conclusions are that target safety is fulfilled, the hazards associated with lithium operation are confined within the IFMIF security boundaries, the environmental impact is negligible, and the plant responds to the simulated transients by being able to reach steady conditions in a safety situation

Assessing soil quality and potential productivity - a basic approach to define and assess the marginality of land

Science.gov (United States)

Repmann, Frank; Gerwin, Werner; Freese, Dirk

2017-04-01

An ever growing demand for energy and the widely proposed switch from fossil fuels to more sustainable energy sources puts the cultivation and use of bioenergy plants into focus. However, bioenergy production on regular and fertile agricultural soils might conflict with the worldwide growing demand for food. To mitigate or omit this potential conflict, the use of low quality or marginal land for cultivation of bioenergy plants becomes favorable. Against this background the definition and assessment of land marginality and, respectively, the evaluation whether and to which extent specific areas are marginal and thus convenient for sustainable bioenergy production, becomes highly relevant. Within the framework of the EU funded Horizon 2020 project SEEMLA, we attempted to asses land marginality of designated test sites in the Ukraine, Greece and Germany by direct field survey. For that purpose, soil and site properties were investigated and evaluated by applying the Muencheberg Soil Quality Rating (SQR) method, developed at the Leibniz Centre for Agricultural Landscape Research (ZALF). The method deploys a comprehensive set of biogeophysical and chemical indicators to describe and finally evaluate the quality of the soil and site by a score ranging from 1 to 100 points. Field survey data were supported by additional laboratory tests on a representative set of soil samples. Practical field work and analysis of field and lab data from the investigated sites proved the applicability of the SQR method within the SEEMLA context. The SQR indices calculated from the field and lab data ranged from 2 to Greece and Germany, which differed considerably in respect to their characteristics. Correlating the site quality index to yield data reflecting yield estimations for common bioenergy plants such as willow (Salix sp.), black locust (Robinia pseudoacacia) and poplar (Populus sp.) cultivated at the respective test sites, revealed that SQR might additionally reflect the potential

Assessment of Biomass Resources from Marginal Lands in APEC Economies

Energy Technology Data Exchange (ETDEWEB)

Milbrandt, A.; Overend, R. P.

2009-08-01

The goal of this study is to examine the marginal lands in Asia-Pacific Economic Cooperation (APEC) economies and evaluate their biomass productivity potential. Twelve categories of marginal lands are identified using the Global Agro-Ecological Zones system of the United Nations Food and Agriculture Organization.

WE-AB-209-08: Novel Beam-Specific Adaptive Margins for Reducing Organ-At-Risk Doses

Energy Technology Data Exchange (ETDEWEB)

Tsang, H; Kamerling, CP; Ziegenhein, P; Nill, S; Oelfke, U [The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London (United Kingdom)

2016-06-15

Purpose: Current practice of using 3D margins in radiotherapy with high-energy photon beams provides larger-than-required target coverage. According to the photon depth-dose curve, target displacements in beam direction result in minute changes in dose delivered. We exploit this behavior by generating margins on a per-beam basis which simultaneously account for the relative distance of the target and adjacent organs-at-risk (OARs). Methods: For each beam, we consider only geometrical uncertainties of the target location perpendicular to beam direction. By weighting voxels based on its proximity to an OAR, we generate adaptive margins that yield similar overall target coverage probability and reduced OAR dose-burden, at the expense of increased target volume. Three IMRT plans, using 3D margins and 2D per-beam margins with and without adaptation, were generated for five prostate patients with a prescription dose Dpres of 78Gy in 2Gy fractions using identical optimisation constraints. Systematic uncertainties of 1.1, 1.1, 1.5mm in the LR, SI, and AP directions, respectively, and 0.9, 1.1, 1.0mm for the random uncertainties, were assumed. A verification tool was employed to simulate the effects of systematic and random errors using a population size of 50,000. The fraction of the population that satisfies or violates a given DVH constraint was used for comparison. Results: We observe similar target coverage across all plans, with at least 97.5% of the population meeting the D98%>95%Dpres constraint. When looking at the probability of the population receiving D5<70Gy for the rectum, we observed median absolute increases of 23.61% (range, 2.15%–27.85%) and 6.97% (range, 0.65%–17.76%) using per-beam margins with and without adaptation, respectively, relative to using 3D margins. Conclusion: We observed sufficient and similar target coverage using per-beam margins. By adapting each per-beam margin away from an OAR, we can further reduce OAR dose without significantly

WE-AB-209-08: Novel Beam-Specific Adaptive Margins for Reducing Organ-At-Risk Doses

International Nuclear Information System (INIS)

Tsang, H; Kamerling, CP; Ziegenhein, P; Nill, S; Oelfke, U

2016-01-01

Purpose: Current practice of using 3D margins in radiotherapy with high-energy photon beams provides larger-than-required target coverage. According to the photon depth-dose curve, target displacements in beam direction result in minute changes in dose delivered. We exploit this behavior by generating margins on a per-beam basis which simultaneously account for the relative distance of the target and adjacent organs-at-risk (OARs). Methods: For each beam, we consider only geometrical uncertainties of the target location perpendicular to beam direction. By weighting voxels based on its proximity to an OAR, we generate adaptive margins that yield similar overall target coverage probability and reduced OAR dose-burden, at the expense of increased target volume. Three IMRT plans, using 3D margins and 2D per-beam margins with and without adaptation, were generated for five prostate patients with a prescription dose Dpres of 78Gy in 2Gy fractions using identical optimisation constraints. Systematic uncertainties of 1.1, 1.1, 1.5mm in the LR, SI, and AP directions, respectively, and 0.9, 1.1, 1.0mm for the random uncertainties, were assumed. A verification tool was employed to simulate the effects of systematic and random errors using a population size of 50,000. The fraction of the population that satisfies or violates a given DVH constraint was used for comparison. Results: We observe similar target coverage across all plans, with at least 97.5% of the population meeting the D98%>95%Dpres constraint. When looking at the probability of the population receiving D5<70Gy for the rectum, we observed median absolute increases of 23.61% (range, 2.15%–27.85%) and 6.97% (range, 0.65%–17.76%) using per-beam margins with and without adaptation, respectively, relative to using 3D margins. Conclusion: We observed sufficient and similar target coverage using per-beam margins. By adapting each per-beam margin away from an OAR, we can further reduce OAR dose without significantly

Facility target insert shielding assessment

Energy Technology Data Exchange (ETDEWEB)

Mocko, Michal [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2015-10-06

Main objective of this report is to assess the basic shielding requirements for the vertical target insert and retrieval port. We used the baseline design for the vertical target insert in our calculations. The insert sits in the 12”-diameter cylindrical shaft extending from the service alley in the top floor of the facility all the way down to the target location. The target retrieval mechanism is a long rod with the target assembly attached and running the entire length of the vertical shaft. The insert also houses the helium cooling supply and return lines each with 2” diameter. In the present study we focused on calculating the neutron and photon dose rate fields on top of the target insert/retrieval mechanism in the service alley. Additionally, we studied a few prototypical configurations of the shielding layers in the vertical insert as well as on the top.

Seismic Margin Assessment for Research Reactor using Fragility based Fault Tree Analysis

Energy Technology Data Exchange (ETDEWEB)

Kwag, Shinyoung; Oh, Jinho; Lee, Jong-Min; Ryu, Jeong-Soo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-10-15

The research reactor has been often subjected to external hazards during the design lifetime. Especially, a seismic event can be one of significant threats to the failure of structure system of the research reactor. This failure is possibly extended to the direct core damage of the reactor. For this purpose, the fault tree for structural system failure leading to the core damage under an earthquake accident is developed. The failure probabilities of basic events are evaluated as fragility curves of log-normal distributions. Finally, the plant-level seismic margin is investigated by the fault tree analysis combining with fragility data and the critical path is identified. The plant-level probabilistic seismic margin assessment using the fragility based fault tree analysis was performed for quantifying the safety of research reactor to a seismic hazard. For this, the fault tree for structural system failure leading to the core damage of the reactor under a seismic accident was developed. The failure probabilities of basic events were evaluated as fragility curves of log-normal distributions.

Assessing mediation using marginal structural models in the presence of confounding and moderation

OpenAIRE

Coffman, Donna L.; Zhong, Wei

2012-01-01

This paper presents marginal structural models (MSMs) with inverse propensity weighting (IPW) for assessing mediation. Generally, individuals are not randomly assigned to levels of the mediator. Therefore, confounders of the mediator and outcome may exist that limit causal inferences, a goal of mediation analysis. Either regression adjustment or IPW can be used to take confounding into account, but IPW has several advantages. Regression adjustment of even one confounder of the mediator and ou...

Establishing seismic design criteria to achieve an acceptable seismic margin

International Nuclear Information System (INIS)

Kennedy, R.P.

1997-01-01

In order to develop a risk based seismic design criteria the following four issues must be addressed: (1) What target annual probability of seismic induced unacceptable performance is acceptable? (2). What minimum seismic margin is acceptable? (3) Given the decisions made under Issues 1 and 2, at what annual frequency of exceedance should the Safe Shutdown Earthquake ground motion be defined? (4) What seismic design criteria should be established to reasonably achieve the seismic margin defined under Issue 2? The first issue is purely a policy decision and is not addressed in this paper. Each of the other three issues are addressed. Issues 2 and 3 are integrally tied together so that a very large number of possible combinations of responses to these two issues can be used to achieve the target goal defined under Issue 1. Section 2 lays out a combined approach to these two issues and presents three potentially attractive combined resolutions of these two issues which reasonably achieves the target goal. The remainder of the paper discusses an approach which can be used to develop seismic design criteria aimed at achieving the desired seismic margin defined in resolution of Issue 2. Suggestions for revising existing seismic design criteria to more consistently achieve the desired seismic margin are presented

Task Group on Safety Margins Action Plan (SMAP). Safety Margins Action Plan - Final Report

International Nuclear Information System (INIS)

Hrehor, Miroslav; Gavrilas, Mirela; Belac, Josef; Sairanen, Risto; Bruna, Giovanni; Reocreux, Michel; Touboul, Francoise; Krzykacz-Hausmann, B.; Park, Jong Seuk; Prosek, Andrej; Hortal, Javier; Sandervaag, Odbjoern; Zimmerman, Martin

2007-01-01

The international nuclear community has expressed concern that some changes in existing plants could challenge safety margins while fulfilling all the regulatory requirements. In 1998, NEA published a report by the Committee on Nuclear Regulatory Activities on Future Nuclear Regulatory Challenges. The report recognized 'Safety margins during more exacting operating modes' as a technical issue with potential regulatory impact. Examples of plant changes that can cause such exacting operating modes include power up-rates, life extension or increased fuel burnup. In addition, the community recognized that the cumulative effects of simultaneous changes in a plant could be larger than the accumulation of the individual effects of each change. In response to these concerns, CSNI constituted the safety margins action plan (SMAP) task group with the following objectives: 'To agree on a framework for integrated assessments of the changes to the overall safety of the plant as a result of simultaneous changes in plant operation / condition; To develop a CSNI document which can be used by member countries to assess the effect of plant change on the overall safety of the plant; To share information and experience.' The two approaches to safety analysis, deterministic and probabilistic, use different methods and have been developed mostly independently of each other. This makes it difficult to assure consistency between them. As the trend to use information on risk (where the term risk means results of the PSA/PRA analysis) to support regulatory decisions is growing in many countries, it is necessary to develop a method of evaluating safety margin sufficiency that is applicable to both approaches and, whenever possible, integrated in a consistent way. Chapter 2 elaborates on the traditional view of safety margins and the means by which they are currently treated in deterministic analyses. This chapter also discusses the technical basis for safety limits as they are used today

Intra-operative Cerenkov Imaging for Guiding Breast Cancer Surgery and Assessing Tumor Margins

Science.gov (United States)

2014-03-01

application, 13/492,606 • One travel award to attend WMIC in Dublin (2012) • One class taught as lead instructor ( Mechatronics system ) • Three classes...paraffin- embedded tissue: five years on. Cytometry. 1989;10:229–241. 15. Meng LJ, Fu G, Roy EJ, Suppe B, Chen CT. An ultrahigh resolution SPECT system for...residual cancer. This grant aims to develop a system to assess tumor margins during surgery, with the eventual goal of reducing re-excision surgery

Extraction of data from margin calculations in prostate radiotherapy from a commercial record and verify system

International Nuclear Information System (INIS)

Fox, C.; Kron, T.; Fisher, R.; Tai, K.H.; Thompson, A.; Owen, R.

2008-01-01

Full text: Radiation therapy is a widely prescribed and effective modality for the treatment of prostate cancer.1 3 Radiation therapy relies on precise targeting of the treatment site to deliver the required dose to the tumour while sparing critical organs nearby. To achieve this, it is necessary to allow for the effects of organ and patient motion, both during and between treatment fractions. In the treatment planning process, a margin is added to the clinical target volume (CTV) to create the planning target volume (PTV) to allow for targeting uncertainties which Iare dominated by these movements.4 5 Deciding the appropriate margin size is important since an excessively large margin will result in increased damage to adjacent normal tissues while an undersized margin will leave parts of the target underdosed. With the marked improvement in technology available with new treatment machines, remote online setup correction using high quality kilovoltage images has become straightforward and widely available. Used together with implanted radio-opaque markers, remote online setup correction allows direct targeting of the prostate organ, and significant reduction in the effects of interfraction motion.6 1 1 The introduction of this technology into a therapy department makes a reduction of CTV to PTV margin size possible. There are many published works dealing with margin size calculation for prostate treatment planning. The best known and most widely cited work is that of van Herk which modelled the prostate using simple geometry to calculate a minimum dose coverage probability.13 The outcome of this modelling was a simple and easily understood formula with just the patient group random and systematic setup errors used to calculate margin size. To apply such margin recipes, the patient group's random and systematic error performance must be well known, which requires the collection of a substantial quantity of data. The aim of the project described here was to collect

Validation of micro-CT against the section method regarding the assessment of marginal leakage of sealants.

NARCIS (Netherlands)

Chen, X.; Cuijpers, V.M.J.I.; Fan, M.W.; Frencken, J.E.F.M.

2012-01-01

BACKGROUND: The aim of this study was to validate the micro-CT and related software against the section method using the stereomicroscope for marginal leakage assessment along the sealant-enamel interface. METHODS: Pits and fissures of the occlusal surface of 10 teeth were sealed with a

Marginal abatement cost curves and the optimal timing of mitigation measures

International Nuclear Information System (INIS)

Vogt-Schilb, Adrien; Hallegatte, Stéphane

2014-01-01

Decision makers facing abatement targets need to decide which abatement measures to implement, and in which order. Measure-explicit marginal abatement cost curves depict the cost and abating potential of available mitigation options. Using a simple intertemporal optimization model, we demonstrate why this information is not sufficient to design emission reduction strategies. Because the measures required to achieve ambitious emission reductions cannot be implemented overnight, the optimal strategy to reach a short-term target depends on longer-term targets. For instance, the best strategy to achieve European's −20% by 2020 target may be to implement some expensive, high-potential, and long-to-implement options required to meet the −75% by 2050 target. Using just the cheapest abatement options to reach the 2020 target can create a carbon-intensive lock-in and make the 2050 target too expensive to reach. Designing mitigation policies requires information on the speed at which various measures to curb greenhouse gas emissions can be implemented, in addition to the information on the costs and potential of such measures provided by marginal abatement cost curves. - Highlights: • Classification of existing Marginal Abatement Cost Curves (MACC). • MACCs do not provide separated data on the speed at which measures can be implemented. • Optimal measures to reach a short-term target depend on longer-term targets. • Unique carbon price or aggregated emission-reduction target may be insufficient. • Room for short-term sectoral policies if agents are myopic or governments cannot commit

Image-Guided Radiotherapy via Daily Online Cone-Beam CT Substantially Reduces Margin Requirements for Stereotactic Lung Radiotherapy

International Nuclear Information System (INIS)

Grills, Inga S.; Hugo, Geoffrey; Kestin, Larry L.; Galerani, Ana Paula; Chao, K. Kenneth; Wloch, Jennifer; Yan Di

2008-01-01

Purpose: To determine treatment accuracy and margins for stereotactic lung radiotherapy with and without cone-beam CT (CBCT) image guidance. Methods and Materials: Acquired for the study were 308 CBCT of 24 patients with solitary peripheral lung tumors treated with stereotactic radiotherapy. Patients were immobilized in a stereotactic body frame (SBF) or alpha-cradle and treated with image guidance using daily CBCT. Four (T1) or five (T2/metastatic) 12-Gy fractions were prescribed to the planning target volume (PTV) edge. The PTV margin was ≥5 mm depending on a pretreatment estimate of tumor excursion. Initial daily setup was according to SBF coordinates or tattoos for alpha-cradle cases. A CBCT was performed and registered to the planning CT using soft tissue registration of the target. The initial setup error/precorrection position, was recorded for the superior-inferior, anterior-posterior, and medial-lateral directions. The couch was adjusted to correct the tumor positional error. A second CBCT verified tumor position after correction. Patients were treated in the corrected position after the residual errors were ≤2 mm. A final CBCT after treatment assessed intrafraction tumor displacement. Results: The precorrection systematic (Σ) and random errors (σ) for the population ranged from 2-3 mm for SBF and 2-6 mm for alpha-cradle patients; postcorrection errors ranged from 0.4-1.0 mm. Calculated population margins were 9 to 13 mm (SBF) and 10-14 mm (cradle) precorrection, 1-2 mm (SBF), and 2-3 mm (cradle) postcorrection, and 2-4 mm (SBF) and 2-5 mm (cradle) posttreatment. Conclusions: Setup for stereotactic lung radiotherapy using a SBF or alpha-cradle alone is suboptimal. CBCT image guidance significantly improves target positioning and substantially reduces required target margins and normal tissue irradiation

Patterns of failure for glioblastoma multiforme following limited-margin radiation and concurrent temozolomide

International Nuclear Information System (INIS)

Gebhardt, Brian J; Dobelbower, Michael C; Ennis, William H; Bag, Asim K; Markert, James M; Fiveash, John B

2014-01-01

To analyze patterns of failure in patients with glioblastoma multiforme (GBM) treated with limited-margin radiation therapy and concurrent temozolomide. We hypothesize that patients treated with margins in accordance with Adult Brain Tumor Consortium guidelines (ABTC) will demonstrate patterns of failure consistent with previous series of patients treated with 2–3 cm margins. A retrospective review was performed of patients treated at the University of Alabama at Birmingham for GBM between 2000 and 2011. Ninety-five patients with biopsy-proven disease and documented disease progression after treatment were analyzed. The initial planning target volume includes the T1-enhancing tumor and surrounding edema plus a 1 cm margin. The boost planning target volume includes the T1-enhancing tumor plus a 1 cm margin. The tumors were classified as in-field, marginal, or distant if greater than 80%, 20-80%, or less than 20% of the recurrent volume fell within the 95% isodose line, respectively. The median progression-free survival from the time of diagnosis to documented failure was 8 months (range 3–46). Of the 95 documented recurrences, 77 patients (81%) had an in-field component of treatment failure, 6 (6%) had a marginal component, and 27 (28%) had a distant component. Sixty-three patients (66%) demonstrated in-field only recurrence. The low rate of marginal recurrence suggests that wider margins would have little impact on the pattern of failure, validating the use of limited margins in accordance ABTC guidelines

Assessment of three-dimensional setup errors in image-guided pelvic radiotherapy for uterine and cervical cancer using kilovoltage cone-beam computed tomography and its effect on planning target volume margins.

Science.gov (United States)

Patni, Nidhi; Burela, Nagarjuna; Pasricha, Rajesh; Goyal, Jaishree; Soni, Tej Prakash; Kumar, T Senthil; Natarajan, T

2017-01-01

To achieve the best possible therapeutic ratio using high-precision techniques (image-guided radiation therapy/volumetric modulated arc therapy [IGRT/VMAT]) of external beam radiation therapy in cases of carcinoma cervix using kilovoltage cone-beam computed tomography (kV-CBCT). One hundred and five patients of gynecological malignancies who were treated with IGRT (IGRT/VMAT) were included in the study. CBCT was done once a week for intensity-modulated radiation therapy and daily in IGRT/VMAT. These images were registered with the planning CT scan images and translational errors were applied and recorded. In all, 2078 CBCT images were studied. The margins of planning target volume were calculated from the variations in the setup. The setup variation was 5.8, 10.3, and 5.6 mm in anteroposterior, superoinferior, and mediolateral direction. This allowed adequate dose delivery to the clinical target volume and the sparing of organ at risks. Daily kV-CBCT is a satisfactory method of accurate patient positioning in treating gynecological cancers with high-precision techniques. This resulted in avoiding geographic miss.

Realistic respiratory motion margins for external beam partial breast irradiation

Energy Technology Data Exchange (ETDEWEB)

Conroy, Leigh; Quirk, Sarah [Department of Medical Physics, Tom Baker Cancer Centre, Calgary, Alberta T2N 4N2 (Canada); Department of Physics and Astronomy, University of Calgary, Calgary, Alberta T2N 1N4 (Canada); Smith, Wendy L., E-mail: wendy.smith@albertahealthservices.ca [Department of Medical Physics, Tom Baker Cancer Centre, Calgary, Alberta T2N 4N2 (Canada); Department of Physics and Astronomy, University of Calgary, Calgary, Alberta T2N 1N4 (Canada); Department of Oncology, University of Calgary, Calgary, Alberta T2N 1N4 (Canada)

2015-09-15

described. It was found that the currently used respiratory margin of 5 mm in partial breast irradiation may be overly conservative for many 3DCRT PBI patients. Amplitude alone was found to be insufficient to determine patient-specific margins: individual respiratory trace shape and baseline drift both contributed to the dosimetric target coverage. With respiratory coaching, individualized respiratory margins smaller than the full extent of motion could reduce planning target volumes while ensuring adequate coverage under respiratory motion.

Realistic respiratory motion margins for external beam partial breast irradiation

International Nuclear Information System (INIS)

Conroy, Leigh; Quirk, Sarah; Smith, Wendy L.

2015-01-01

described. It was found that the currently used respiratory margin of 5 mm in partial breast irradiation may be overly conservative for many 3DCRT PBI patients. Amplitude alone was found to be insufficient to determine patient-specific margins: individual respiratory trace shape and baseline drift both contributed to the dosimetric target coverage. With respiratory coaching, individualized respiratory margins smaller than the full extent of motion could reduce planning target volumes while ensuring adequate coverage under respiratory motion

Specimen Shrinkage and Its Influence on Margin Assessment in Breast Cancer

Directory of Open Access Journals (Sweden)

Badrul H. Yeap

2007-07-01

Conclusion: Breast specimens undergo shrinkage after histological fixation, losing more than a third of their original closest free margin, whilst the tumour itself does not shrink substantially. This phenomenon has vital implications in the accuracy of margin analysis and consequent decisions on further management, including re-operation and the institution of adjuvant radiotherapy.

Marginal abatement cost curves for NOx incorporating both controls and alternative measures

Science.gov (United States)

A marginal abatement cost curve (MACC) traces out the efficient marginal abatement cost level for any aggregate emissions target when a least cost approach is implemented. In order for it to represent the efficient MAC level, all abatement opportunities across all sectors and loc...

Seismic margin analysis technique for nuclear power plant structures

International Nuclear Information System (INIS)

Seo, Jeong Moon; Choi, In Kil

2001-04-01

In general, the Seismic Probabilistic Risk Assessment (SPRA) and the Seismic Margin Assessment(SAM) are used for the evaluation of realistic seismic capacity of nuclear power plant structures. Seismic PRA is a systematic process to evaluate the seismic safety of nuclear power plant. In our country, SPRA has been used to perform the probabilistic safety assessment for the earthquake event. SMA is a simple and cost effective manner to quantify the seismic margin of individual structural elements. This study was performed to improve the reliability of SMA results and to confirm the assessment procedure. To achieve this goal, review for the current status of the techniques and procedures was performed. Two methodologies, CDFM (Conservative Deterministic Failure Margin) sponsored by NRC and FA (Fragility Analysis) sponsored by EPRI, were developed for the seismic margin review of NPP structures. FA method was originally developed for Seismic PRA. CDFM approach is more amenable to use by experienced design engineers including utility staff design engineers. In this study, detailed review on the procedures of CDFM and FA methodology was performed

Respiratory gated beam delivery cannot facilitate margin reduction, unless combined with respiratory correlated image guidance

International Nuclear Information System (INIS)

Korreman, Stine S.; Juhler-Nottrup, Trine; Boyer, Arthur L.

2008-01-01

Purpose/objective: In radiotherapy of targets moving with respiration, beam gating is offered as a means of reducing the target motion. The purpose of this study is to evaluate the safe magnitude of margin reduction for respiratory gated beam delivery. Materials/methods: The study is based on data for 17 lung cancer patients in separate protocols at Rigshospitalet and Stanford Cancer Center. Respiratory curves for external optical markers and implanted fiducials were collected using equipment based on the RPM system (Varian Medical Systems). A total of 861 respiratory curves represented external measurements over 30 fraction treatment courses for 10 patients, and synchronous external/internal measurements in single sessions for seven patients. Variations in respiratory amplitude (simulated coaching) and external/internal phase shifts were simulated by perturbation with realistic values. Variations were described by medians and standard deviations (SDs) of position distributions of the markers. Gating windows (35% duty cycle) were retrospectively applied to the respiratory data for each session, mimicking the use of commercially available gating systems. Medians and SDs of gated data were compared to those of ungated data, to assess potential margin reductions. Results: External respiratory data collected over entire treatment courses showed SDs from 1.6 to 8.1 mm, the major part arising from baseline variations. The gated data had SDs from 1.5 to 7.7 mm, with a mean reduction of 0.3 mm (6%). Gated distributions were more skewed than ungated, and in a few cases a marginal miss of gated respiration would be found even if no margin reduction was applied. Regularization of breathing amplitude to simulate coaching did not alter these results significantly. Simulation of varying phase shifts between internal and external respiratory signals showed that the SDs of gated distributions were the same as for the ungated or smaller, but the median values were markedly shifted

Marginal Generation Technology in the Chinese Power Market towards 2030 Based on Consequential Life Cycle Assessment

DEFF Research Database (Denmark)

Zhao, Guangling; Guerrero, Josep M.; Pei, Yingying

2016-01-01

Electricity consumption is often the hotspot of life cycle assessment (LCA) of products, industrial activities, or services. The objective of this paper is to provide a consistent, scientific, region-specific electricity-supply-based inventory of electricity generation technology for national...... and regional power grids. Marginal electricity generation technology is pivotal in assessing impacts related to additional consumption of electricity. China covers a large geographical area with regional supply grids; these are arguably equally or less integrated. Meanwhile, it is also a country with internal...

Benefit–cost analysis of non-marginal climate and energy projects

International Nuclear Information System (INIS)

Dietz, Simon; Hepburn, Cameron

2013-01-01

Conventional benefit–cost analysis incorporates the normally reasonable assumption that the policy or project under examination is marginal. Among the assumptions this entails is that the policy or project is small, so the underlying growth rate of the economy does not change. However, this assumption may be inappropriate in some important circumstances, including in climate-change and energy policy. One example is global targets for carbon emissions, while another is a large renewable energy project in a small economy, such as a hydropower dam. This paper develops some theory on the evaluation of non-marginal projects, with empirical applications to climate change and energy. We examine the conditions under which evaluation of a non-marginal project using marginal methods may be wrong, and in our empirical examples we show that both qualitative and large quantitative errors are plausible. - Highlights: • This paper develops the theory of the evaluation of non-marginal projects. • It also includes empirical applications to climate change and energy. • We show when evaluation of a non-marginal project using marginal methods is wrong

A two-cassette reporter system for assessing target gene translation and target gene product inclusion body formation

DEFF Research Database (Denmark)

2016-01-01

The present invention relates to a dual cassette reporter system capable of assessing target gene translation and target gene product folding. The present invention further relates to vectors and host cells comprising the dual cassette reporter system. In addition the invention relates to the use...... of the dual cassette reporter system for assessing target gene translation and target gene product folding....

Reinforcing marginality? Maternal health interventions in rural Nicaragua.

Science.gov (United States)

Kvernflaten, Birgit

2017-06-23

To achieve Millennium Development Goal 5 on maternal health, many countries have focused on marginalized women who lack access to care. Promoting facility-based deliveries to ensure skilled birth attendance and emergency obstetric care has become a main measure for preventing maternal deaths, so women who opt for home births are often considered 'marginal' and in need of targeted intervention. Drawing upon ethnographic data from Nicaragua, this paper critically examines the concept of marginality in the context of official efforts to increase institutional delivery amongst the rural poor, and discusses lack of access to health services among women living in peripheral areas as a process of marginalization. The promotion of facility birth as the new norm, in turn, generates a process of 're-marginalization', whereby public health officials morally disapprove of women who give birth at home, viewing them as non-compliers and a problem to the system. In rural Nicaragua, there is a discrepancy between the public health norm and women's own preferences and desires for home birth. These women live at the margins also in spatial and societal terms, and must relate to a health system they find incapable of providing good, appropriate care. Strong public pressure for institutional delivery makes them feel distressed and pressured. Paradoxically then, the aim of including marginal groups in maternal health programmes engenders resistance to facility birth.

Safety assessment for the passive system of the nuclear power plants (NPPs) using safety margin estimation

International Nuclear Information System (INIS)

Woo, Tae-Ho; Lee, Un-Chul

2010-01-01

The probabilistic safety assessment (PSA) for gas-cooled nuclear power plants has been investigated where the operational data are deficient, because there is not any commercial gas-cooled nuclear power plant. Therefore, it is necessary to use the statistical data for the basic event constructions. Several estimations for the safety margin are introduced for the quantification of the failure frequency in the basic event, which is made by the concept of the impact and affordability. Trend of probability of failure (TPF) and fuzzy converter (FC) are introduced using the safety margin, which shows the simplified and easy configurations for the event characteristics. The mass flow rate in the natural circulation is studied for the modeling. The potential energy in the gravity, the temperature and pressure in the heat conduction, and the heat transfer rate in the internal stored energy are also investigated. The values in the probability set are compared with those of the fuzzy set modeling. Non-linearity of the safety margin is expressed by the fuzziness of the membership function. This artificial intelligence analysis of the fuzzy set could enhance the reliability of the system comparing to the probabilistic analysis.

Assessment of margins in resection specimens for head and neck malignancies.

Science.gov (United States)

Janjua, Omer Sefvan; Ahmed, Waseem; Qureshi, Sana Mehmood; Khan, Tariq Sarfaraz; Ahmed, Ashfaq; Alamgir, Wajiha

2013-04-01

To determine the relative frequency of clear, close and involved margins in resection specimens for head and neck malignancies. An observational study. The Department of Oral and Maxillofacial Surgery, Armed Forces Institute of Dentistry, Rawalpindi and the Department of Histopathology, Armed Forces Institute of Pathology, Rawalpindi, from January 2008 to December 2010. Tumour registers and computer data bases in the department of Histopathology of Armed Forces Institute of Pathology, Rawalpindi, were analyzed for the cases of malignancies involving head and neck region that were sent for histopathological analysis after resection in the last three years. Histopathology reports were obtained. The data regarding age, gender, site, type of malignancy and margin status (clear, close or involved) was recorded on specially designed proformas for the study and later on analyzed by using SPSS version 17.0. Results were expressed. A total of 319 cases were registered in the study duration. The age of the patients ranged from 22-90 years (mean 59.5 + 14.1 years). Male to female ratio was 1.53:1. One hundred and thirty six (42.6%) were squamous cell carcinoma (SCC), 163 were basal cell carcinomas (BCC, 51.0%); the rest included 18 salivary gland malignancies (5.7%) and one carcino-sarcoma (0.31%) and chondrosarcoma each. All margins were found clear in 137 patients (42.9%); involved in 168 cases (52.7%) and close in 14 cases (4.4%). Margin clearance could not be achieved in more than 50% cases, this can lead to poor prognosis. Hence, methods should be adopted to improve the margin clearance in various head and neck malignancies.

Assessment of margins in resection specimens for head and neck malignancies

International Nuclear Information System (INIS)

Janjua, O. S.; Ahmed, W.; Ahmed, A.; Qureshi, S. M.; Khan, T. S.; Alamgir, W.

2013-01-01

Objective: To determine the relative frequency of clear, close and involved margins in resection specimens for head and neck malignancies. Study Design: An observational study. Place and Duration of Study: The Department of Oral and Maxillofacial Surgery, Armed Forces Institute of Dentistry, Rawalpindi and the Department of Histopathology, Armed Forces Institute of Pathology, Rawalpindi, from January 2008 to December 2010. Methodology: Tumour registers and computer data bases in the department of Histopathology of Armed Forces Institute of Pathology, Rawalpindi, were analyzed for the cases of malignancies involving head and neck region that were sent for histopathological analysis after resection in the last three years. Histopathology reports were obtained. The data regarding age, gender, site, type of malignancy and margin status (clear, close or involved) was recorded on specially designed proformas for the study and later on analyzed by using SPSS version 17.0. Results were expressed. Results: A total of 319 cases were registered in the study duration. The age of the patients ranged from 22 - 90 years (mean 59.5 + 14.1 years). Male to female ratio was 1.53:1. One hundred and thirty six (42.6%) were squamous cell carcinoma (SCC), 163 were basal cell carcinomas (BCC, 51.0%); the rest included 18 salivary gland malignancies (5.7%) and one carcino-sarcoma (0.31%) and chondrosarcoma each. All margins were found clear in 137 patients (42.9%); involved in 168 cases (52.7%) and close in 14 cases (4.4%). Conclusion: Margin clearance could not be achieved in more than 50% cases, this can lead to poor prognosis. Hence, methods should be adopted to improve the margin clearance in various head and neck malignancies. (author)

Assessment of CASP7 structure predictions for template free targets.

Science.gov (United States)

Jauch, Ralf; Yeo, Hock Chuan; Kolatkar, Prasanna R; Clarke, Neil D

2007-01-01

In CASP7, protein structure prediction targets that lacked substantial similarity to a protein in the PDB at the time of assessment were considered to be free modeling targets (FM). We assessed predictions for 14 FM targets as well as four other targets that were deemed to be on the borderline between FM targets and template based modeling targets (TBM/FM). GDT_TS was used as one measure of model quality. Model quality was also assessed by visual inspection. Visual inspection was performed by three independent assessors who were blinded to GDT_TS scores and other quantitative measures of model quality. The best models by visual inspection tended to rank among the top few percent by GDT_TS, but were typically not the highest scoring models. Thus, visual inspection remains an essential component of assessment for FM targets. Overall, group TS020 (Baker) performed best, but success on individual targets was widely distributed among many groups. Among these other groups, TS024 and TS025 (Zhang and Zhang server) performed notably well without exceptionally large computing resources. This should be considered encouraging for future CASPs. There was a sense of progress in template FM relative to CASP6, but we were unable to demonstrate this progress objectively. (c) 2007 Wiley-Liss, Inc.

Convolution method and CTV-to-PTV margins for finite fractions and small systematic errors

International Nuclear Information System (INIS)

Gordon, J J; Siebers, J V

2007-01-01

The van Herk margin formula (VHMF) relies on the accuracy of the convolution method (CM) to determine clinical target volume (CTV) to planning target volume (PTV) margins. This work (1) evaluates the accuracy of the CM and VHMF as a function of the number of fractions N and other parameters, and (2) proposes an alternative margin algorithm which ensures target coverage for a wider range of parameter values. Dose coverage was evaluated for a spherical target with uniform margin, using the same simplified dose model and CTV coverage criterion as were used in development of the VHMF. Systematic and random setup errors were assumed to be normally distributed with standard deviations Σ and σ. For clinically relevant combinations of σ, Σ and N, margins were determined by requiring that 90% of treatment course simulations have a CTV minimum dose greater than or equal to the static PTV minimum dose. Simulation results were compared with the VHMF and the alternative margin algorithm. The CM and VHMF were found to be accurate for parameter values satisfying the approximate criterion: σ[1 - γN/25] 0.2, because they failed to account for the non-negligible dose variability associated with random setup errors. These criteria are applicable when σ ∼> σ P , where σ P = 0.32 cm is the standard deviation of the normal dose penumbra. (Qualitative behaviour of the CM and VHMF will remain the same, though the criteria might vary if σ P takes values other than 0.32 cm.) When σ P , dose variability due to random setup errors becomes negligible, and the CM and VHMF are valid regardless of the values of Σ and N. When σ ∼> σ P , consistent with the above criteria, it was found that the VHMF can underestimate margins for large σ, small Σ and small N. A potential consequence of this underestimate is that the CTV minimum dose can fall below its planned value in more than the prescribed 10% of treatments. The proposed alternative margin algorithm provides better margin

Intraoperative monitoring of marginal mandibular nerve during neck dissection.

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Tirelli, Giancarlo; Bergamini, Pier Riccardo; Scardoni, Alessandro; Gatto, Annalisa; Boscolo Nata, Francesca; Marcuzzo, Alberto Vito

2018-05-01

The purpose of this study was to assess the efficacy of intraoperative nerve integrity monitoring (NIM) to prevent marginal mandibular nerve injuries during neck dissection. This prospective study compared 36 patients undergoing NIM-assisted neck dissection from July 2014 to March 2015 to a cohort of 35 patients subjected to neck dissection over an identical period of time before the technique was introduced. We also assessed possible correlations between marginal mandibular nerve injuries and other factors, such as anthropometric measurements, presence of clinical neck metastases, type of neck dissection, and site of primary tumor. The incidence of marginal mandibular nerve paralyses was significantly lower among the group of patients undergoing NIM-assisted neck dissection (P = .021). There was no significant difference in the duration of the procedure, and the technique resulted in a limited increase of cost. No other factor seemed to influence the onset of marginal mandibular nerve palsy. In our opinion, NIM is a valuable aid for preventing marginal mandibular nerve injuries during neck dissection. © 2018 Wiley Periodicals, Inc.

Portable optical fiber probe-based spectroscopic scanner for rapid cancer diagnosis: a new tool for intraoperative margin assessment.

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Niyom Lue

Full Text Available There continues to be a significant clinical need for rapid and reliable intraoperative margin assessment during cancer surgery. Here we describe a portable, quantitative, optical fiber probe-based, spectroscopic tissue scanner designed for intraoperative diagnostic imaging of surgical margins, which we tested in a proof of concept study in human tissue for breast cancer diagnosis. The tissue scanner combines both diffuse reflectance spectroscopy (DRS and intrinsic fluorescence spectroscopy (IFS, and has hyperspectral imaging capability, acquiring full DRS and IFS spectra for each scanned image pixel. Modeling of the DRS and IFS spectra yields quantitative parameters that reflect the metabolic, biochemical and morphological state of tissue, which are translated into disease diagnosis. The tissue scanner has high spatial resolution (0.25 mm over a wide field of view (10 cm × 10 cm, and both high spectral resolution (2 nm and high spectral contrast, readily distinguishing tissues with widely varying optical properties (bone, skeletal muscle, fat and connective tissue. Tissue-simulating phantom experiments confirm that the tissue scanner can quantitatively measure spectral parameters, such as hemoglobin concentration, in a physiologically relevant range with a high degree of accuracy (<5% error. Finally, studies using human breast tissues showed that the tissue scanner can detect small foci of breast cancer in a background of normal breast tissue. This tissue scanner is simpler in design, images a larger field of view at higher resolution and provides a more physically meaningful tissue diagnosis than other spectroscopic imaging systems currently reported in literatures. We believe this spectroscopic tissue scanner can provide real-time, comprehensive diagnostic imaging of surgical margins in excised tissues, overcoming the sampling limitation in current histopathology margin assessment. As such it is a significant step in the development of a

Margin benefit assessment of the YGN 3 cycle 1 fxy error files for COLSS and CPC overall uncertainty analyses

International Nuclear Information System (INIS)

Yoon, Rae Young; In, Wang Kee; Auh, Geun Sun; Kim, Hee Cheol; Lee, Sang Keun

1994-01-01

Margin benefits are quantitatively assessed for the Yonggwang Unit 3 (YGN 3) Cycle 1 planar radial peaking factor (Fxy) error files for each time-in-life, i.e., BOC, IOC, MOC and EOC. The generic Fxy error file (FXYMEQO) is presently used for Yonggwang Unit 3 Cycle 1 COLSS (Core Operating Limit Supervisory System) and CPC (Core Protection Calculator) Overall Uncertainty Analyses (OUA). However, because this file is more conservative than the plant/cycle specific Fxy error files, COLSS and CPC thermal margins (DNB-OPM) for the generic Fxy error file are less than those of the plant/cycle specific Fxy error file. Therefore, the YGN 3 Cycle 1 Fxy error files were generated and analyzed by the modified codes for Yonggwang Plants. The YGN 3 Cycle 1 Fxy error files gave the increased thermal margin by about 1% for COLSS and CPC, respectively

Inserting ex vivo fluorescence confocal microscopy perioperatively in Mohs micrographic surgery expedites bedside assessment of excision margins in recurrent basal cell carcinoma.

Science.gov (United States)

Longo, Caterina; Ragazzi, Moira; Castagnetti, Fabio; Gardini, Stefano; Palmieri, Tamara; Lallas, Aimilios; Moscarella, Elvira; Piana, Simonetta; Pellacani, Giovanni; Zalaudek, Iris; Argenziano, Giuseppe

2013-01-01

Mohs micrographic surgery can be employed in recurrent basal cell carcinoma, although it is a time-consuming technique. Recently, ex vivo fluorescence confocal microscopy (FCM) has been employed to obtain a fast assessment of tumor margins at the bedside. In our case we successfully employed ex vivo FCM to assess the tumor margins and we treated the persistent tumor with intensity-modulated radiation therapy. Our case demonstrates that a multidisciplinary approach is very efficient in managing complex and recurrent tumors and highlights the benefits of FCM as a new technique that can be used in the surgical theater to speed up the entire procedure.

An IGRT margin concept for pelvic lymph nodes in high-risk prostate cancer

International Nuclear Information System (INIS)

Groher, M.; Kopp, P.; Deutschmann, H.; Sedlmayer, F.; Wolf, Frank; Drerup, M.

2017-01-01

Gold-marker-based image-guided radiation therapy (IGRT) of the prostate allows to correct for inter- and intrafraction motion and therefore to safely reduce margins for the prostate planning target volume (PTV). However, pelvic PTVs, when coadministered in a single plan (registered to gold markers [GM]), require reassessment of the margin concept since prostate movement is independent from the pelvic bony anatomy to which the lymphatics are usually referenced to. We have therefore revisited prostate translational movement relative to the bony anatomy to obtain adequate margins for the pelvic PTVs compensating mismatch resulting from referencing pelvic target volumes to GMs in the prostate. Prostate movement was analyzed in a set of 28 patients (25 fractions each, totaling in 684 fractions) and the required margins calculated for the pelvic PTVs according to Van Herk's margin formula M = 2.5 Σ + 1.64 (σ ' -σ p ). The overall mean prostate movement relative to bony anatomy was 0.9 ± 3.1, 0.6 ± 3.4, and 0.0 ± 0.7 mm in anterior/posterior (A/P), inferior/superior (I/S) and left/right (L/R) direction, respectively. Calculated margins to compensate for the resulting mismatch to bony anatomy were 9/9/2 mm in A/P, I/S, and L/R direction and 10/11/6 mm if an additional residual error of 2 mm was assumed. GM-based IGRT for pelvic PTVs is feasible if margins are adapted accordingly. Margins could be reduced further if systematic errors which are introduced during the planning CT were eliminated. (orig.) [de

Quantifying Appropriate PTV Setup Margins: Analysis of Patient Setup Fidelity and Intrafraction Motion Using Post-Treatment Megavoltage Computed Tomography Scans

International Nuclear Information System (INIS)

Drabik, Donata M.; MacKenzie, Marc A.; Fallone, Gino B.

2007-01-01

Purpose: To present a technique that can be implemented in-house to evaluate the efficacy of immobilization and image-guided setup of patients with different treatment sites on helical tomotherapy. This technique uses an analysis of alignment shifts between kilovoltage computed tomography and post-treatment megavoltage computed tomography images. The determination of the shifts calculated by the helical tomotherapy software for a given site can then be used to define appropriate planning target volume internal margins. Methods and Materials: Twelve patients underwent post-treatment megavoltage computed tomography scans on a helical tomotherapy machine to assess patient setup fidelity and net intrafraction motion. Shifts were studied for the prostate, head and neck, and glioblastoma multiforme. Analysis of these data was performed using automatic and manual registration of the kilovoltage computed tomography and post-megavoltage computed tomography images. Results: The shifts were largest for the prostate, followed by the head and neck, with glioblastoma multiforme having the smallest shifts in general. It appears that it might be more appropriate to use asymmetric planning target volume margins. Each margin value reported is equal to two standard deviations of the average shift in the given direction. Conclusion: This method could be applied using individual patient post-image scanning and combined with adaptive planning to reduce or increase the margins as appropriate

Evaluation of the setup margins for cone beam computed tomography–guided cranial radiosurgery: A phantom study

Energy Technology Data Exchange (ETDEWEB)

Calvo Ortega, Juan Francisco, E-mail: jfcdrr@yahoo.es [Department of Radiation Oncology, Hospital Quirón, Barcelona (Spain); Wunderink, Wouter [Department of Radiotherapy, Erasmus MC Cancer Institute, University Medical Center Rotterdam, Rotterdam (Netherlands); Delgado, David; Moragues, Sandra; Pozo, Miquel; Casals, Joan [Department of Radiation Oncology, Hospital Quirón, Barcelona (Spain)

2016-10-01

The aim of this study is to evaluate the setup margins from the clinical target volume (CTV) to planning target volume (PTV) for cranial stereotactic radiosurgery (SRS) treatments guided by cone beam computed tomography (CBCT). We designed an end-to-end (E2E) test using a skull phantom with an embedded 6mm tungsten ball (target). A noncoplanar plan was computed (E2E plan) to irradiate the target. The CBCT-guided positioning of the skull phantom on the linac was performed. Megavoltage portal images were acquired after 15 independent deliveries of the E2E plan. The displacement 2-dimensional (2D) vector between the centers of the square field and the ball target on each portal image was used to quantify the isocenter accuracy. Geometrical margins on each patient's direction (left-right or LR, anterior-posterior or AP, superior-inferior or SI) were calculated. Dosimetric validation of the margins was performed in 5 real SRS cases: 3-dimesional (3D) isocenter deviations were mimicked, and changes in CTV dose coverage and organs-at-risk (OARs) dosage were analyzed. The CTV-PTV margins of 1.1 mm in LR direction, and 0.7 mm in AP and SI directions were derived from the E2E tests. The dosimetric analysis revealed that a 1-mm uniform margin was sufficient to ensure the CTV dose coverage, without compromising the OAR dose tolerances. The effect of isocenter uncertainty has been estimated to be 1 mm in our CBCT-guided SRS approach.

Texas curve margin of safety.

Science.gov (United States)

2013-01-01

This software can be used to assist with the assessment of margin of safety for a horizontal curve. It is intended for use by engineers and technicians responsible for safety analysis or management of rural highway pavement or traffic control devices...

Utilization of cone-beam CT for offline evaluation of target volume coverage during prostate image-guided radiotherapy based on bony anatomy alignment.

Science.gov (United States)

Paluska, Petr; Hanus, Josef; Sefrova, Jana; Rouskova, Lucie; Grepl, Jakub; Jansa, Jan; Kasaova, Linda; Hodek, Miroslav; Zouhar, Milan; Vosmik, Milan; Petera, Jiri

2012-01-01

To assess target volume coverage during prostate image-guided radiotherapy based on bony anatomy alignment and to assess possibility of safety margin reduction. Implementation of IGRT should influence safety margins. Utilization of cone-beam CT provides current 3D anatomic information directly in irradiation position. Such information enables reconstruction of the actual dose distribution. Seventeen prostate patients were treated with daily bony anatomy image-guidance. Cone-beam CT (CBCT) scans were acquired once a week immediately after bony anatomy alignment. After the prostate, seminal vesicles, rectum and bladder were contoured, the delivered dose distribution was reconstructed. Target dose coverage was evaluated by the proportion of the CTV encompassed by the 95% isodose. Original plans employed a 1 cm safety margin. Alternative plans assuming a smaller 7 mm margin between CTV and PTV were evaluated in the same way. Rectal and bladder volumes were compared with the initial ones. Rectal and bladder volumes irradiated with doses higher than 75 Gy, 70 Gy, 60 Gy, 50 Gy and 40 Gy were analyzed. In 12% of reconstructed plans the prostate coverage was not sufficient. The prostate underdosage was observed in 5 patients. Coverage of seminal vesicles was not satisfactory in 3% of plans. Most of the target underdosage corresponded to excessive rectal or bladder filling. Evaluation of alternative plans assuming a smaller 7 mm margin revealed 22% and 11% of plans where prostate and seminal vesicles coverage, respectively, was compromised. These were distributed over 8 and 7 patients, respectively. Sufficient dose coverage of target volumes was not achieved for all patients. Reducing of safety margin is not acceptable. Initial rectal and bladder volumes cannot be considered representative for subsequent treatment.

Study on structural seismic margin and probabilistic seismic risk. Development of a structural capacity-seismic risk diagram

International Nuclear Information System (INIS)

Nakajima, Masato; Ohtori, Yasuki; Hirata, Kazuta

2010-01-01

Seismic margin is extremely important index and information when we evaluate and account seismic safety of critical structures, systems and components quantitatively. Therefore, it is required that electric power companies evaluate the seismic margin of each plant in back-check of nuclear power plants in Japan. The seismic margin of structures is usually defined as a structural capacity margin corresponding to design earthquake ground motion. However, there is little agreement as to the definition of the seismic margin and we have no knowledge about a relationship between the seismic margin and seismic risk (annual failure probability) which is obtained in PSA (Probabilistic Safety Assessment). The purpose of this report is to discuss a definition of structural seismic margin and to develop a diagram which can identify a relation between seismic margin and seismic risk. The main results of this paper are described as follows: (1) We develop seismic margin which is defined based on the fact that intensity of earthquake ground motion is more appropriate than the conventional definition (i.e., the response-based seismic margin) for the following reasons: -seismic margin based on earthquake ground motion is invariant where different typed structures are considered, -stakeholders can understand the seismic margin based on the earthquake ground motion better than the response-based one. (2) The developed seismic margin-risk diagram facilitates us to judge easily whether we need to perform detailed probabilistic risk analysis or only deterministic analysis, given that the reference risk level although information on the uncertainty parameter beta is not obtained. (3) We have performed numerical simulations based on the developed method for four sites in Japan. The structural capacity-risk diagram differs depending on each location because the diagram is greatly influenced by seismic hazard information for a target site. Furthermore, the required structural capacity

Integrating respiratory-gated PET-based target volume delineation in liver SBRT planning, a pilot study

International Nuclear Information System (INIS)

Riou, Olivier; Thariat, Juliette; Serrano, Benjamin; Azria, David; Paulmier, Benoit; Villeneuve, Remy; Fenoglietto, Pascal; Artenie, Antonella; Ortholan, Cécile; Faraggi, Marc

2014-01-01

To assess the feasibility and benefit of integrating four-dimensional (4D) Positron Emission Tomography (PET) – computed tomography (CT) for liver stereotactic body radiation therapy (SBRT) planning. 8 patients with 14 metastases were accrued in the study. They all underwent a non-gated PET and a 4D PET centered on the liver. The same CT scan was used for attenuation correction, registration, and considered the planning CT for SBRT planning. Six PET phases were reconstructed for each 4D PET. By applying an individualized threshold to the 4D PET, a Biological Internal Target Volume (BITV) was generated for each lesion. A gated Planning Target Volume (PTVg) was created by adding 3 mm to account for set-up margins. This volume was compared to a manual Planning Target Volume (PTV) delineated with the help of a semi-automatic Biological Target Volume (BTV) obtained from the non-gated exam. A 5 mm radial and a 10 mm craniocaudal margins were applied to account for tumor motion and set-up margins to create the PTV. One undiagnosed liver metastasis was discovered thanks to the 4D PET. The semi-automatic BTV were significantly smaller than the BITV (p = 0.0031). However, after applying adapted margins, 4D PET allowed a statistically significant decrease in the PTVg as compared to the PTV (p = 0.0052). In comparison to non-gated PET, 4D PET may better define the respiratory movements of liver targets and improve SBRT planning for liver metastases. Furthermore, non respiratory-gated PET exams can both misdiagnose liver metastases and underestimate the real internal target volumes

Seismic margin review of the Maine Yankee Atomic Power Station: Fragility analysis

International Nuclear Information System (INIS)

Ravindra, M.K.; Hardy, G.S.; Hashimoto, P.S.; Griffin, M.J.

1987-03-01

This Fragility Analysis is the third of three volumes for the Seismic Margin Review of the Maine Yankee Atomic Power Station. Volume 1 is the Summary Report of the first trial seismic margin review. Volume 2, Systems Analysis, documents the results of the systems screening for the review. The three volumes are part of the Seismic Margins Program initiated in 1984 by the Nuclear Regulatory Commission (NRC) to quantify seismic margins at nuclear power plants. The overall objectives of the trial review are to assess the seismic margins of a particular pressurized water reactor, and to test the adequacy of this review approach, quantification techniques, and guidelines for performing the review. Results from the trial review will be used to revise the seismic margin methodology and guidelines so that the NRC and industry can readily apply them to assess the inherent quantitative seismic capacity of nuclear power plants

Seismic margin review of the Maine Yankee Atomic Power Station: Fragility analysis

Energy Technology Data Exchange (ETDEWEB)

Ravindra, M. K.; Hardy, G. S.; Hashimoto, P. S.; Griffin, M. J.

1987-03-01

This Fragility Analysis is the third of three volumes for the Seismic Margin Review of the Maine Yankee Atomic Power Station. Volume 1 is the Summary Report of the first trial seismic margin review. Volume 2, Systems Analysis, documents the results of the systems screening for the review. The three volumes are part of the Seismic Margins Program initiated in 1984 by the Nuclear Regulatory Commission (NRC) to quantify seismic margins at nuclear power plants. The overall objectives of the trial review are to assess the seismic margins of a particular pressurized water reactor, and to test the adequacy of this review approach, quantification techniques, and guidelines for performing the review. Results from the trial review will be used to revise the seismic margin methodology and guidelines so that the NRC and industry can readily apply them to assess the inherent quantitative seismic capacity of nuclear power plants.

Relief for marginal wells is better than energy tax

International Nuclear Information System (INIS)

Swords, J.; Wilson, D.

1993-01-01

By increasing production costs and reducing petroleum prices, President Bill Clinton's proposed energy tax would increase marginal well abandonments and hasten the decline of the US oil and gas industry. Instead, the US needs tax law changes to help counteract the increasing number of oil and gas well abandonments in the lower 48 states. The proposed tax would create potential difficulties, while three incentives could be introduced to reduce abandonments and at the same time preserve US government tax revenues that otherwise would be lost. Eliminating the net income limitation on percentage depletion allowances on wells that would otherwise be abandoned would be a great help for marginal well operators. Extended enhanced oil recovery (EOR) credits and broader investment tax credits could also serve the dual purpose of keeping marginal wells operating longer and generating more federal tax revenues. A marginal well investment tax credit should be provided that is not just a credit for incremented investments that exceed investment in prior years. An investment tax credit based on out-of-pocket costs of production, targeted for marginal wells, would be an important incentive to invest in, and continue to maintain, these properties. (author)

Sustainable food production in marginal lands—Case of GDLA member countries

Directory of Open Access Journals (Sweden)

Shabbir A. Shahid

2013-06-01

Full Text Available Sustainable food production in the changing climate and dwindling water resources in the Global Dry Land Alliance (GDLA member countries is a real challenge, especially when considering marginal lands in dryland systems. The definition of marginal land is very vague and defined from different perspectives (pragmatism about marginal lands. Dryland itself indicates "marginality" due to water stress. In general, the abandoned agriculture land where food production is not economical, and has low inherent productivity potential is considered marginal; however, a land may be marginal for agriculture but vital for grazing. In this paper attempts have been made to give review of literature (water stress, extent of marginal saline lands, marginality. Policy matters (development of soil, water and agriculture strategies that GDLA and member countries should consider for future sustainable food production in their countries, including but not limited to, assessment of land resources for agriculture potential, defining, mapping and characterizing marginal lands, and use of innovative technologies (conservation agriculture, climate smart agriculture, integrated soil reclamation program and capacity building for food production, are discussed. The international perception (FAO, UNEP, CGIAR on marginal lands is also described. An innovative approach of using national biocapacity and ecological footprint is used to assess marginality of GDLA member countries. Ecological overshoot (using 1.5 earth planets and biocapacity debtor and creditor countries are highlighted. Challenges and best management practices for food production in marginal lands are included. Other important issues, like leasing land abroad, GDLA strategic food reserves and best management practices, innovative ideas for food production are shared. Finally recommendations are drafted for actions by GDLA, its member countries and the partners.

Effect of Margin Designs on the Marginal Adaptation of Zirconia Copings.

Science.gov (United States)

Habib, Syed Rashid; Al Ajmi, Mohammed Ginan; Al Dhafyan, Mohammed; Jomah, Abdulrehman; Abualsaud, Haytham; Almashali, Mazen

2017-09-01

The aim of this in vitro study was to investigate the effect of Shoulder versus Chamfer margin design on the marginal adaptation of zirconia (Zr) copings. 40 extracted molar teeth were mounted in resin and prepared for zirconia crowns with two margin preparation designs (20=Shoulder and 20=Chamfer). The copings were manufactured by Cercon® (DeguDent GmbH, Germany) using the CAD/CAM system for each tooth. They were tried on each tooth, cemented, thermocycled, re-embedded in resin and were subsequently cross sectioned centrally into two equal mesial and distal halves. They were examined under electron microscope at 200 X magnification and the measurements were recorded at 5 predetermined points in micrometers (µm). The o verall mean marginal gap for the two groups was found to be 206.98+42.78µm with Shoulder margin design (Marginal Gap=199.50+40.72µm) having better adaptation compared to Chamfer (Marginal Gap=214.46+44.85µm). The independent-samples t-test showed a statistically non-significant difference (p=.113) between the means of marginal gap for Shoulder and Chamfer margin designs and the measurements were recorded at 5 predetermined points for the two groups. The Chamfer margin design appeared to offer the same adaptation results as the Shoulder margin design.

Identifying technology innovations for marginalized smallholders-A conceptual approach.

Science.gov (United States)

Malek, Mohammad Abdul; Gatzweiler, Franz W; Von Braun, Joachim

2017-05-01

This paper adds a contribution in the existing literature in terms of theoretical and conceptual background for the identification of idle potentials of marginal rural areas and people by means of technological and institutional innovations. The approach follows ex-ante assessment for identifying suitable technology and institutional innovations for marginalized smallholders in marginal areas-divided into three main parts (mapping, surveying and evaluating) and several steps. Finally, it contributes to the inclusion of marginalized smallholders by an improved way of understanding the interactions between technology needs, farming systems, ecological resources and poverty characteristics in the different segments of the poor, and to link these insights with productivity enhancing technologies.

Postoperative Intensity-Modulated Radiotherapy for Squamous Cell Carcinoma of the External Auditory Canal and Middle Ear: Treatment Outcomes, Marginal Misses, and Perspective on Target Delineation

International Nuclear Information System (INIS)

Chen, Wan-Yu; Kuo, Sung-Hsin; Chen, Yu-Hsuan; Lu, Szu-Huai; Tsai, Chiao-Ling; Chia-Hsien Cheng, Jason; Hong, Ruey-Long; Chen, Ya-Fang; Hsu, Chuan-Jen; Lin, Kai-Nan; Ko, Jenq-Yuh; Lou, Pei-Jen; Wang, Cheng-Ping; Chong, Fok-Ching; Wang, Chun-Wei

2012-01-01

Purpose: To report outcomes of the rare disease of squamous cell carcinoma (SCC) of the external auditory canal (EAC) and middle ear treated with surgery and postoperative intensity-modulated radiotherapy (IMRT). Failure patterns related to spatial dose distribution were also analyzed to provide insight into target delineation. Methods and Materials: A retrospective review was conducted of the records of 11 consecutive patients with SCC of the EAC and middle ear who were treated with curative surgery and postoperative IMRT at one institution between January 2007 and February 2010. The prescribed IMRT dose was 60 to 66 Gy at 2 Gy per fraction. Three patients also received concurrent cisplatin-based chemotherapy, and 1 patient received concurrent oral tegafur/uracil. The median follow-up time was 19 months (range, 6–33 months). Results: Four patients had locoregional recurrence, yielding an estimated 2-year locoregional control rate of 70.7%. Among them, 1 patient had persistent disease after treatment, and 3 had marginal recurrence. Distant metastasis occurred in 1 patient after extensive locoregional recurrence, yielding an estimated 2-year distant control rate of 85.7%. The estimated 2-year overall survival was 67.5%. The three cases of marginal recurrence were near the preauricular space and glenoid fossa of the temporomandibular joint, adjacent to the apex of the ear canal and glenoid fossa of the temporomandibular joint, and in the postauricular subcutaneous area and ipsilateral parotid nodes, respectively. Conclusions: Marginal misses should be recognized to improve target delineation. When treating SCC of the EAC and middle ear, care should be taken to cover the glenoid fossa of the temporomandibular joint and periauricular soft tissue. Elective ipsilateral parotid irradiation should be considered. The treatment planning procedure should also be refined to balance subcutaneous soft-tissue dosimetry and toxicity.

Postoperative Intensity-Modulated Radiotherapy for Squamous Cell Carcinoma of the External Auditory Canal and Middle Ear: Treatment Outcomes, Marginal Misses, and Perspective on Target Delineation

Energy Technology Data Exchange (ETDEWEB)

Chen, Wan-Yu [Division of Radiation Oncology, Department of Oncology, National Taiwan University Hospital, Taipei, Taiwan (China); Kuo, Sung-Hsin [Division of Radiation Oncology, Department of Oncology, National Taiwan University Hospital, Taipei, Taiwan (China); Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei, Taiwan (China); Chen, Yu-Hsuan; Lu, Szu-Huai; Tsai, Chiao-Ling [Division of Radiation Oncology, Department of Oncology, National Taiwan University Hospital, Taipei, Taiwan (China); Chia-Hsien Cheng, Jason [Division of Radiation Oncology, Department of Oncology, National Taiwan University Hospital, Taipei, Taiwan (China); Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei, Taiwan (China); Graduate Institute of Oncology, National Taiwan University College of Medicine, Taipei, Taiwan (China); Hong, Ruey-Long [Division of Medical Oncology, Department of Oncology, National Taiwan University Hospital, Taipei, Taiwan (China); Chen, Ya-Fang [Department of Medical Imaging, National Taiwan University Hospital, Taipei, Taiwan (China); Hsu, Chuan-Jen; Lin, Kai-Nan; Ko, Jenq-Yuh; Lou, Pei-Jen; Wang, Cheng-Ping [Department of Otolaryngology, National Taiwan University Hospital, Taipei, Taiwan (China); Chong, Fok-Ching [Graduate Institute of Electrical Engineering, National Taiwan University, Taipei, Taiwan (China); Wang, Chun-Wei, E-mail: cwwang@ntuh.gov.tw [Graduate Institute of Electrical Engineering, National Taiwan University, Taipei, Taiwan (China)

2012-03-15

Purpose: To report outcomes of the rare disease of squamous cell carcinoma (SCC) of the external auditory canal (EAC) and middle ear treated with surgery and postoperative intensity-modulated radiotherapy (IMRT). Failure patterns related to spatial dose distribution were also analyzed to provide insight into target delineation. Methods and Materials: A retrospective review was conducted of the records of 11 consecutive patients with SCC of the EAC and middle ear who were treated with curative surgery and postoperative IMRT at one institution between January 2007 and February 2010. The prescribed IMRT dose was 60 to 66 Gy at 2 Gy per fraction. Three patients also received concurrent cisplatin-based chemotherapy, and 1 patient received concurrent oral tegafur/uracil. The median follow-up time was 19 months (range, 6-33 months). Results: Four patients had locoregional recurrence, yielding an estimated 2-year locoregional control rate of 70.7%. Among them, 1 patient had persistent disease after treatment, and 3 had marginal recurrence. Distant metastasis occurred in 1 patient after extensive locoregional recurrence, yielding an estimated 2-year distant control rate of 85.7%. The estimated 2-year overall survival was 67.5%. The three cases of marginal recurrence were near the preauricular space and glenoid fossa of the temporomandibular joint, adjacent to the apex of the ear canal and glenoid fossa of the temporomandibular joint, and in the postauricular subcutaneous area and ipsilateral parotid nodes, respectively. Conclusions: Marginal misses should be recognized to improve target delineation. When treating SCC of the EAC and middle ear, care should be taken to cover the glenoid fossa of the temporomandibular joint and periauricular soft tissue. Elective ipsilateral parotid irradiation should be considered. The treatment planning procedure should also be refined to balance subcutaneous soft-tissue dosimetry and toxicity.

Assessment of Long-Run Marginal Costing of Transmission and ...

African Journals Online (AJOL)

The Long-Run Marginal Costing (LRMC) technique is used as a cost-reflecting pricing method and finds useful application in the recovery of the total investment cost for the use of a transmission or distribution network. This paper reviews recent applications of this technique based on some examples from United Kingdom, ...

Pilot study of intraoperative digital imaging with the use of a mammograph for assessment of bone surgical margins in the head and neck region

International Nuclear Information System (INIS)

Ntomouchtsis, A.; Xinou, K.; Patrikidou, A.; Paraskevopoulos, K.; Kechagias, N.; Tsekos, A.; Balis, G.C.; Gerasimidou, D.; Thuau, H.; Mangoudi, D.; Vahtsevanos, K.

2013-01-01

Aim: To investigate alternative possibilities for the intraoperative evaluation of surgical margins after bone resection utilizing more conventional hospital infrastructure technologies. Materials and methods: A small pilot study was performed using digital mammograph imaging intraoperatively on 16 surgical specimens of bone tumours or malignancies with bone infiltration of the head and neck area, with the aim of evaluating the resection margins. Results: In thirteen cases the intraoperative specimen images indicated clinically complete excision. In two cases incomplete resection or close proximity of margins was detected, which required additional resection. Conclusions: The results indicated that intraoperative specimen radiography can prove useful in evaluating completeness of excision. The significance of intraoperative assessment of surgical margin is of paramount importance when immediate reconstruction is performed. This proposed method is cheap, easy to perform and fast. Its cost–benefit ratio is superior than that of any other available technique. Intraoperative analysis of specimens with digital mammography imaging can potentially become a useful tool for immediate evaluation of osseous margins after resection

Incorporating latitudinal and central–marginal trends in assessing genetic variation across species ranges

Science.gov (United States)

Qinfeng Guo

2012-01-01

The genetic variation across a species’ range is an important factor in speciation and conservation, yet searching for general patterns and underlying causes remains challenging. While the majority of comparisons between central and marginal populations have revealed a general central–marginal (C-M) decline in genetic diversity, others show no clear pattern. Similarly...

Study to Determine Adequate Margins in Radiotherapy Planning for Esophageal Carcinoma by Detailing Patterns of Recurrence After Definitive Chemoradiotherapy

International Nuclear Information System (INIS)

Button, Michael R.; Morgan, Carys A.; Croydon, Elizabeth S.; Roberts, S. Ashley; Crosby, Thomas D.L.

2009-01-01

Purpose: To ascertain the adequacy of radiotherapy (RT) margins by studying the relapse patterns after definitive chemoradiotherapy for carcinoma of the esophagus. Methods and Materials: We performed a retrospective study assessing the first site of disease relapse after definitive chemoradiotherapy that included four 3-weekly cycles of cisplatin and continuous infusion 5-fluorouracil, with conformal RT (50 Gy in 25 fractions) concurrent with Cycles 3 and 4. The RT planning target volume was the endoscopic ultrasonography/computed tomography-defined gross tumor volume with 1.5-cm lateral and 3-cm superoinferior margins. Results: A total of 145 patients were included. Their average age was 65.4 years, 45% had adenocarcinoma, 61% had lower third esophageal tumors, and 75% had Stage III-IVA disease. After RT, of 142 patients, 85 (60%) had evidence of relapse at a median follow-up of 18 months. The relapse was local (within the RT field) in 55; distant (metastatic) in 13, and a combination of local and distant in 14. The local relapse rates were not influenced by tumor stage, lymph node status, or disease length. Three patients developed a relapse in regions adjacent to the RT fields; however, it is unlikely that larger field margins would have been clinically acceptable or effective in these cases. The median overall survival was 15 months. Conclusion: The gross tumor volume-planning target volume margins in this study appeared adequate. Future efforts to improve outcomes using definitive chemoradiotherapy should be directed toward reducing the high rates of in-field and distant relapses

Analysis of PTV margin for IMRT and VMAT techniques in prostate cancer using IGRT

International Nuclear Information System (INIS)

Sandrini, E.S.; Silveira, T.B.; Vieira, D.S.; Anjos, L.E.A.; Lopez, J.C.C.; Batista, D.V.S.

2014-01-01

Clinical radiotherapy procedures aim at high precision. However, there are many errors sources that act during treatment preparation and execution that limit its accuracy. The use of imaged-guided radiotherapy (IGRT) increases the agreement between the planned dose and the actual dose deposited in the target, at the same time allows to evaluate the uncertainties related to the setup and a possible reduction in the planning target volume (PTV) margin. Thus the aim of this study was to determine the best PTV margin to be used in radiotherapy treatment of prostate cancer using intensity modulated radiotherapy (IMRT) and volumetric modulated arc radiotherapy (VMAT) techniques associated with IGRT. A total of four patients with prostate daily cone beam computed tomography (CBCT) were analyzed. Systematic and random errors were calculated statistically based on the displacements couch for 128 CBCTs. It was found that a symmetric margin of 0.75 cm from clinical treatment volume (CTV) to PTV is sufficient to encompass the uncertainties inherent to the treatment applying IGRT. Besides without that and maintaining the same tumor control probability, a symmetric margin of 1,24 cm would be necessary. This study showed that using daily image verification the setup errors are reduced, which generates a lower PTV margin. (author)

Assessing Probabilistic Risk Assessment Approaches for Insect Biological Control Introductions.

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Kaufman, Leyla V; Wright, Mark G

2017-07-07

The introduction of biological control agents to new environments requires host specificity tests to estimate potential non-target impacts of a prospective agent. Currently, the approach is conservative, and is based on physiological host ranges determined under captive rearing conditions, without consideration for ecological factors that may influence realized host range. We use historical data and current field data from introduced parasitoids that attack an endemic Lepidoptera species in Hawaii to validate a probabilistic risk assessment (PRA) procedure for non-target impacts. We use data on known host range and habitat use in the place of origin of the parasitoids to determine whether contemporary levels of non-target parasitism could have been predicted using PRA. Our results show that reasonable predictions of potential non-target impacts may be made if comprehensive data are available from places of origin of biological control agents, but scant data produce poor predictions. Using apparent mortality data rather than marginal attack rate estimates in PRA resulted in over-estimates of predicted non-target impact. Incorporating ecological data into PRA models improved the predictive power of the risk assessments.

Assessing Reliability of Cold Spray Sputter Targets in Photovoltaic Manufacturing

Science.gov (United States)

Hardikar, Kedar; Vlcek, Johannes; Bheemreddy, Venkata; Juliano, Daniel

2017-10-01

Cold spray has been used to manufacture more than 800 Cu-In-Ga (CIG) sputter targets for deposition of high-efficiency photovoltaic thin films. It is a preferred technique since it enables high deposit purity and transfer of non-equilibrium alloy states to the target material. In this work, an integrated approach to reliability assessment of such targets with deposit weight in excess of 50 lb. is undertaken, involving thermal-mechanical characterization of the material in as-deposited condition, characterization of the interface adhesion on cylindrical substrate in as-deposited condition, and developing means to assess target integrity under thermal-mechanical loads during the physical vapor deposition (PVD) sputtering process. Mechanical characterization of cold spray deposited CIG alloy is accomplished through the use of indentation testing and adaptation of Brazilian disk test. A custom lever test was developed to characterize adhesion along the cylindrical interface between the CIG deposit and cylindrical substrate, overcoming limitations of current standards. A cohesive zone model for crack initiation and propagation at the deposit interface is developed and validated using the lever test and later used to simulate the potential catastrophic target failure in the PVD process. It is shown that this approach enables reliability assessment of sputter targets and improves robustness.

Formulation, computation and improvement of steady state security margins in power systems. Part II: Results

International Nuclear Information System (INIS)

Echavarren, F.M.; Lobato, E.; Rouco, L.; Gomez, T.

2011-01-01

A steady state security margin for a particular operating point can be defined as the distance from this initial point to the secure operating limits of the system. Four of the most used steady state security margins are the power flow feasibility margin, the contingency feasibility margin, the load margin to voltage collapse, and the total transfer capability between system areas. This is the second part of a two part paper. Part I has proposed a novel framework of a general model able to formulate, compute and improve any steady state security margin. In Part II the performance of the general model is validated by solving a variety of practical situations in modern real power systems. Actual examples of the Spanish power system will be used for this purpose. The same computation and improvement algorithms outlined in Part I have been applied for the four security margins considered in the study, outlining the convenience of defining a general framework valid for the four of them. The general model is used here in Part II to compute and improve: (a) the power flow feasibility margin (assessing the influence of the reactive power generation limits in the Spanish power system), (b) the contingency feasibility margin (assessing the influence of transmission and generation capacity in maintaining a correct voltage profile), (c) the load margin to voltage collapse (assessing the location and quantity of loads that must be shed in order to be far away from voltage collapse) and (d) the total transfer capability (assessing the export import pattern of electric power between different areas of the Spanish system). (author)

Formulation, computation and improvement of steady state security margins in power systems. Part II: Results

Energy Technology Data Exchange (ETDEWEB)

Echavarren, F.M.; Lobato, E.; Rouco, L.; Gomez, T. [School of Engineering of Universidad Pontificia Comillas, C/Alberto Aguilera, 23, 28015 Madrid (Spain)

2011-02-15

A steady state security margin for a particular operating point can be defined as the distance from this initial point to the secure operating limits of the system. Four of the most used steady state security margins are the power flow feasibility margin, the contingency feasibility margin, the load margin to voltage collapse, and the total transfer capability between system areas. This is the second part of a two part paper. Part I has proposed a novel framework of a general model able to formulate, compute and improve any steady state security margin. In Part II the performance of the general model is validated by solving a variety of practical situations in modern real power systems. Actual examples of the Spanish power system will be used for this purpose. The same computation and improvement algorithms outlined in Part I have been applied for the four security margins considered in the study, outlining the convenience of defining a general framework valid for the four of them. The general model is used here in Part II to compute and improve: (a) the power flow feasibility margin (assessing the influence of the reactive power generation limits in the Spanish power system), (b) the contingency feasibility margin (assessing the influence of transmission and generation capacity in maintaining a correct voltage profile), (c) the load margin to voltage collapse (assessing the location and quantity of loads that must be shed in order to be far away from voltage collapse) and (d) the total transfer capability (assessing the export import pattern of electric power between different areas of the Spanish system). (author)

Matthew and marginality

Directory of Open Access Journals (Sweden)

Denis C. Duling

1995-12-01

Full Text Available This article explores marginality theory as it was first proposed in  the social sciences, that is related to persons caught between two competing cultures (Park; Stonequist, and, then, as it was developed in sociology as related to the poor (Germani and in anthropology as it was related to involuntary marginality and voluntary marginality (Victor Turner. It then examines a (normative scheme' in antiquity that creates involuntary marginality at the macrosocial level, namely, Lenski's social stratification model in an agrarian society, and indicates how Matthean language might fit with a sample inventory  of socioreligious roles. Next, it examines some (normative schemes' in  antiquity for voluntary margi-nality at the microsocial level, namely, groups, and examines how the Matthean gospel would fit based on indications of factions and leaders. The article ,shows that the author of the Gospel of Matthew has an ideology of (voluntary marginality', but his gospel includes some hope for (involuntary  marginals' in  the  real world, though it is somewhat tempered. It also suggests that the writer of the Gospel is a (marginal man', especially in the sense defined by the early theorists (Park; Stone-quist.

Design of planning target volume margin using an active breathing control and Varian image-guided radiotherapy (IGRT) system in unresectable liver tumor

International Nuclear Information System (INIS)

Yue Jinbo; Yu Jinming; Liu Jing; Liu Tonghai; Yin Yong; Shi Xuetao; Song Jinlong

2007-01-01

Objective: To define the planning target volume(PTV) margin with an active breathing control (ABC) and the Varian image-guided radiotherapy (IGRT) system. Methods: Thirteen patients with liver cancer were treated with radiotherapy from May 2006 to September 2006. Prior to radiotherapy, all patients had undergone transarterial chemoembolization (TACE) by infusing a mixture of iodized oil contrast medium and chemotherapeutic agents, kV fluoroscopy was used to measure the potential motion of lipiodol spot positions during ABC breath-holds. ABC was used for planning CT scan and radiation delivery, with the breath held at the same phase of the respiratory cycle (near end-exhalation). Cone beam CT (CBCT) was taken using Varian IGRT system, which was then compared online with planning CT using a 3 D-3 D matching tool. Analysis relied on lipiodol spots on planning CT and CBCT manually. The treatment table was moved to produce acceptable setup before treatment delivery. Repeated CBCT image and another analysis were obtained after irradiation. Results: No motion of the intrahepatic tumor was observed on fluoroscopy during ABC breath-holds. The estimated required PTV margins, calculated according to the Stroom formula, were 4.4 mm, 5.3 mm and 7.8 mm in the x, y and z axis directions before radiotherapy. The corresponding parameters were 2.5m, 2.6 mm and 3.9 mm after radiotherapy. Conclusions: We have adopted a PTV margin of 5 mm, 6 mm and 8 mm in the x, y and z axis directions with ABC, and 3,3 and 4 mm with ABC and on-line kilovoltage CBCT. (authors)

Three-dimensional and topographic relationships between the orbital margins with reference to assessment of eyeball protrusion.

Science.gov (United States)

Shin, Kang-Jae; Lee, Shin-Hyo; Koh, Ki-Seok; Song, Wu-Chul

2017-03-01

This study investigated the topographic relationships among the eyeball and four orbital margins with the aim of identifying the correlation between orbital geometry and eyeball protrusion in Koreans. Three-dimensional (3D) volume rendering of the face was performed using serial computed-tomography images of 141 Koreans, and several landmarks on the bony orbit and the cornea were directly marked on the 3D volumes. The anterior-posterior distances from the apex of the cornea to each orbital margin and between the orbital margins were measured in both eyes. The distances from the apex of the cornea to the superior, medial, inferior, and lateral orbital margins were 5.8, 5.8, 12.0, and 17.9 mm, respectively. Differences between sides were observed in all of the orbital margins, and the distances from the apex of the cornea to the superior and inferior orbital margins were significantly greater in females than in males. The anterior-posterior distance between the superior and inferior orbital margins did not differ significantly between males (6.3 mm) and females (6.2 mm). The data obtained in this study will be useful when developing practical guidelines applicable to forensic facial reconstruction and orbitofacial surgeries.

Assessment of the Agronomic Feasibility of Bioenergy Crop Cultivation on Marginal and Polluted Land: A GIS-Based Suitability Study from the Sulcis Area, Italy

Directory of Open Access Journals (Sweden)

Giuseppe Pulighe

2016-10-01

Full Text Available In the context of environmental sustainability there has been an increasing interest in bioenergy production from renewable resources, and is expected that European biofuel production from energy crops will increase as a consequence of the achievement of policy targets. The aim of this paper is to assess the agronomic feasibility of biomass crop cultivation to provide profitable renewable feedstocks in a marginal and heavy-metal polluted area located in the Sulcis district, Sardinia (Italy. Results from literature review and unpublished data from field trials carried out in Sardinia were analysed to establish the main agronomic traits of crops (e.g., yield potential and input requirements. A Geographical Information System (GIS-based procedure with remotely sensed data is also used to evaluate the land suitability and the actual land use/cover, considering a future scenario of expansion of energy crops on these marginal areas avoiding potential conflicts with food production. The results of the review suggests that giant reed, native perennial grasses and milk thistle are the most suitable energy crops for this area. The land suitability analysis shows that about 5700 ha and 1000 ha could be available for feedstock cultivation in the study area and in the most polluted area, respectively. The results obtained from land suitability process and agronomic evaluation will serve as a base to support technical and economical feasibility studies, as well as for the evaluation of environmental sustainability of the cultivation in the study area.

Seismic margin assessment and earthquake experience based methods for WWER-440/213 type NPPs

International Nuclear Information System (INIS)

Masopust, R.

1996-01-01

This report covers the review of the already completed studies, namely, safe shutdown system identification and classification for Bohunice NPP and the comparative study of standards and criteria. It contains a report on currently ongoing studies concerning seismic margin assessment and earthquake experience based methods in application for seismic evaluation and verification of structures and equipment components of the operating WWER-440/213 type NPPs. This is based on experiences obtained from Paks NPP. The work plan for the remaining period of Benchmark CRP and the new proposals are included. These are concerned with seismic evaluation of selected safety related mechanical equipment and pipes of Paks NPP, and the actual seismic issues of the Temelin WWER-1000 type NPP

Marginal deformations of heterotic G 2 sigma models

Science.gov (United States)

Fiset, Marc-Antoine; Quigley, Callum; Svanes, Eirik Eik

2018-02-01

Recently, the infinitesimal moduli space of heterotic G 2 compactifications was described in supergravity and related to the cohomology of a target space differential. In this paper we identify the marginal deformations of the corresponding heterotic nonlinear sigma model with cohomology classes of a worldsheet BRST operator. This BRST operator is nilpotent if and only if the target space geometry satisfies the heterotic supersymmetry conditions. We relate this to the supergravity approach by showing that the corresponding cohomologies are indeed isomorphic. We work at tree-level in α' perturbation theory and study general geometries, in particular with non-vanishing torsion.

Three independent one-dimensional margins for single-fraction frameless stereotactic radiosurgery brain cases using CBCT

International Nuclear Information System (INIS)

Zhang, Qinghui; Chan, Maria F.; Burman, Chandra; Song, Yulin; Zhang, Mutian

2013-01-01

Purpose: Setting a proper margin is crucial for not only delivering the required radiation dose to a target volume, but also reducing the unnecessary radiation to the adjacent organs at risk. This study investigated the independent one-dimensional symmetric and asymmetric margins between the clinical target volume (CTV) and the planning target volume (PTV) for linac-based single-fraction frameless stereotactic radiosurgery (SRS).Methods: The authors assumed a Dirac delta function for the systematic error of a specific machine and a Gaussian function for the residual setup errors. Margin formulas were then derived in details to arrive at a suitable CTV-to-PTV margin for single-fraction frameless SRS. Such a margin ensured that the CTV would receive the prescribed dose in 95% of the patients. To validate our margin formalism, the authors retrospectively analyzed nine patients who were previously treated with noncoplanar conformal beams. Cone-beam computed tomography (CBCT) was used in the patient setup. The isocenter shifts between the CBCT and linac were measured for a Varian Trilogy linear accelerator for three months. For each plan, the authors shifted the isocenter of the plan in each direction by ±3 mm simultaneously to simulate the worst setup scenario. Subsequently, the asymptotic behavior of the CTV V 80% for each patient was studied as the setup error approached the CTV-PTV margin.Results: The authors found that the proper margin for single-fraction frameless SRS cases with brain cancer was about 3 mm for the machine investigated in this study. The isocenter shifts between the CBCT and the linac remained almost constant over a period of three months for this specific machine. This confirmed our assumption that the machine systematic error distribution could be approximated as a delta function. This definition is especially relevant to a single-fraction treatment. The prescribed dose coverage for all the patients investigated was 96.1%± 5.5% with an extreme

Role of specimen US for predicting resection margin status in breast conserving therapy.

Science.gov (United States)

Moschetta, M; Telegrafo, M; Introna, T; Coi, L; Rella, L; Ranieri, V; Cirili, A; Stabile Ianora, A A; Angelelli, G

2015-01-01

To assess the diagnostic accuracy of specimen ultrasound (US) for predicting resection margin status in women undergoing breast conserving therapy for US-detected cancer, having the histological findings as the reference standard. A total of 132 consecutive patients (age range, 34-87 years; mean, 51 years) underwent breast-conserving surgery for US-detected invasive breast cancer. All surgical specimens underwent US examination. The presence of lesion within the specimen and its distance from the specimen margins were assessed considering a threshold distance between the lesion and specimen margins of 10 mm. US findings were then compared with the pathological ones and specimen US. Sensitivity, specificity, diagnostic accuracy, positive (PPV) and negative predictive values (NPV) for predicting histological margin status were evaluated, having the histological findings as the reference standard. The histological examination detected invasive ductal carcinoma in 96/132 (73%) cases, invasive lobular carcinoma in 32/132 (24%), mucinous carcinoma in 4/132 (3%). The pathological margin analysis revealed 96/132 (73%) negative margins and 36 (27%) close/positive margins. US examination detected all 132 breast lesions within the surgical specimens. 110 (83%) negative margins and 22 (17%) positive margins were found on US. Sensitivity, specificity, diagnostic accuracy, PPV and NPV of 44%, 94%, 80%, 73% and 82%, respectively, were found for specimen US. Specimen US represents a time and cost saving imaging tool for evaluating the presence of US detected-breast lesion within surgical specimen and for predicting the histological margin status.

Controlling marginally detached divertor plasmas

Science.gov (United States)

Eldon, D.; Kolemen, E.; Barton, J. L.; Briesemeister, A. R.; Humphreys, D. A.; Leonard, A. W.; Maingi, R.; Makowski, M. A.; McLean, A. G.; Moser, A. L.; Stangeby, P. C.

2017-06-01

A new control system at DIII-D has stabilized the inter-ELM detached divertor plasma state for H-mode in close proximity to the threshold for reattachment, thus demonstrating the ability to maintain detachment with minimal gas puffing. When the same control system was instead ordered to hold the plasma at the threshold (here defined as T e  =  5 eV near the divertor target plate), the resulting T e profiles separated into two groups with one group consistent with marginal detachment, and the other with marginal attachment. The plasma dithers between the attached and detached states when the control system attempts to hold at the threshold. The control system is upgraded from the one described in Kolemen et al (2015 J. Nucl. Mater. 463 1186) and it handles ELMing plasmas by using real time D α measurements to remove during-ELM slices from real time T e measurements derived from divertor Thomson scattering. The difference between measured and requested inter-ELM T e is passed to a PID (proportional-integral-derivative) controller to determine gas puff commands. While some degree of detachment is essential for the health of ITER’s divertor, more deeply detached plasmas have greater radiative losses and, at the extreme, confinement degradation, making it desirable to limit detachment to the minimum level needed to protect the target plate (Kolemen et al 2015 J. Nucl. Mater. 463 1186). However, the observed bifurcation in plasma conditions at the outer strike point with the ion B   ×  \

Molecular pathogenesis of splenic and nodal marginal zone lymphoma.

Science.gov (United States)

Spina, Valeria; Rossi, Davide

Genomic studies have improved our understanding of the biological basis of splenic (SMZL) and nodal (NMZL) marginal zone lymphoma by providing a comprehensive and unbiased view of the genes/pathways that are deregulated in these diseases. Consistent with the physiological involvement of NOTCH, NF-κB, B-cell receptor and toll-like receptor signaling in mature B-cells differentiation into the marginal zone B-cells, many oncogenic mutations of genes involved in these pathways have been identified in SMZL and NMZL. Beside genetic lesions, also epigenetic and post-transcriptional modifications contribute to the deregulation of marginal zone B-cell differentiation pathways in SMZL and NMZL. This review describes the progress in understanding the molecular mechanism underlying SMZL and NMZL, including molecular and post-transcriptional modifications, and discusses how information gained from these efforts has provided new insights on potential targets of diagnostic, prognostic and therapeutic relevance in SMZL and NMZL. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Systematic Review of Training Interventions Addressing Sexual Violence against Marginalized At-Risk Groups of Women

Science.gov (United States)

Kouta, Christiana; Pithara, Christalla; Zobnina, Anna; Apostolidou, Zoe; Christodoulou, Josie; Papadakaki, Maria; Chliaoutakis, Joannes

2015-01-01

Women from marginalized groups working in occupations such as domestic work are at increased risk for sexual violence. Scarce evidence exists about training interventions targeting such groups. The article aims to identify community and workplace-based training interventions aiming to increase capacity among marginalized at-risk women to deal with…

Marginal and happy? The need for uniqueness predicts the adjustment of marginal immigrants.

Science.gov (United States)

Debrosse, Régine; de la Sablonnière, Roxane; Rossignac-Milon, Maya

2015-12-01

Marginalization is often presented as the strategy associated with the worst adjustment for immigrants. This study identifies a critical variable that buffers marginal immigrants from the negative effects of marginalization on adjustment: The need for uniqueness. In three studies, we surveyed immigrants recruited on university campuses (n = 119, n = 116) and in the field (n = 61). Among marginal immigrants, a higher need for uniqueness predicted higher self-esteem (Study 1), affect (Study 2), and life satisfaction (Study 3), and marginally higher happiness (Study 2) and self-esteem (Study 3). No relationship between the need for uniqueness and adjustment was found among non-marginal immigrants. The adaptive value of the need for uniqueness for marginal immigrants is discussed. © 2015 The British Psychological Society.

Hormesis: from marginalization to mainstream A case for hormesis as the default dose-response model in risk assessment

International Nuclear Information System (INIS)

Calabrese, Edward J.

2004-01-01

The paper provides an account of how the hormetic dose response has emerged in recent years as a serious dose-response model in toxicology and risk assessment after decades of extreme marginalization. In addition to providing the toxicological basis of this dose-response revival, the paper reexamines the concept of a default dose model in toxicology and risk assessment and makes the argument that the hormetic model satisfies criteria (e.g., generalizability, frequency, application to risk assessment endpoints, false positive/negative potential, requirements for hazard assessment, reliability of estimating risks, capacity for validation of risk estimates, public health implications of risk estimates) for such a default model better than its chief competitors, the threshold and linear at low dose models. The selection of the hormetic model as the default model in risk assessment for noncarcinogens and specifically for carcinogens would have a profound impact on the practice of risk assessment and its societal implications

Marginalizing Instrument Systematics in HST WFC3 Transit Light Curves

Science.gov (United States)

Wakeford, H. R.; Sing, D. K.; Evans, T.; Deming, D.; Mandell, A.

2016-03-01

Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) infrared observations at 1.1-1.7 μm probe primarily the H2O absorption band at 1.4 μm, and have provided low-resolution transmission spectra for a wide range of exoplanets. We present the application of marginalization based on Gibson to analyze exoplanet transit light curves obtained from HST WFC3 to better determine important transit parameters such as Rp/R*, which are important for accurate detections of H2O. We approximate the evidence, often referred to as the marginal likelihood, for a grid of systematic models using the Akaike Information Criterion. We then calculate the evidence-based weight assigned to each systematic model and use the information from all tested models to calculate the final marginalized transit parameters for both the band-integrated and spectroscopic light curves to construct the transmission spectrum. We find that a majority of the highest weight models contain a correction for a linear trend in time as well as corrections related to HST orbital phase. We additionally test the dependence on the shift in spectral wavelength position over the course of the observations and find that spectroscopic wavelength shifts {δ }λ (λ ) best describe the associated systematic in the spectroscopic light curves for most targets while fast scan rate observations of bright targets require an additional level of processing to produce a robust transmission spectrum. The use of marginalization allows for transparent interpretation and understanding of the instrument and the impact of each systematic evaluated statistically for each data set, expanding the ability to make true and comprehensive comparisons between exoplanet atmospheres.

SU-E-T-406: Online Image-Guidance for Prostate SBRT: Dosimetric Benefits and Margin Analysis.

Science.gov (United States)

Li, T; Yuan, L; Lee, W; Yin, F; Wu, Q J

2012-06-01

To evaluate the dosimetric benefits of online image guidance during prostate stereotactic body radiotherapy (SBRT) and the potential on margin reduction. 28 prostate SBRT patients were retrospectively studied, each treated with 37Gy in 5 fractions. RTOG recently opened a similar protocol (0938). During treatments, per-beam couch corrections were made based on the actual target motion provided by dynamic tracking with either Calypso or per-beam OBI imaging. Dosimetric benefits of online correction were evaluated by comparing delivered dose distributions with and without such correction. The dose distribution without correction was generated in the same treatment planning system by accumulating doses without online correction from the each beam and each fraction. Quantitative analyses include the dosimetric difference between delivered doses with and without correction; the correction magnitude and frequency; and the potential on margin reduction based on the margin recipe by Van Herk et al. (1) Delivery without online correction results in small reduction on target mean dose (0.03±0.05Gy), maximal dose (0.01±0.06Gy), and conformity index (<0.06). (2) Delivery without online correction has small impact on OAR dose: 26 out of 28 patients have <1%/1.5cc differences in V18.5Gy/V24Gy/V28Gy/V33Gy/V37Gy for both the bladder and the rectum. Maximal differences are 4cc of the bladder and 1.6cc of the rectum in mid-dose regions (V18.5Gy). (3) For femoral heads, <1cc/1Gy differences are observed in V20Gy/Dmean/D1cc.(4) Average number of couch corrections per fraction is 0.49. The magnitudes are: (-0.2±2)mm vertically, (-0.1±2.1)mm longitudinally, and (-0.2±1.4)mm laterally. (5) Margin determined by actual target motion in this patient population is 2.5mm isotropic. For both target coverage and OAR sparing, overall small benefit is seen from per-beam couch correction under dynamic tracking. The target motion between beams is small and random, and indicates a population

Assessing Probabilistic Risk Assessment Approaches for Insect Biological Control Introductions

Directory of Open Access Journals (Sweden)

Leyla V. Kaufman

2017-07-01

Full Text Available The introduction of biological control agents to new environments requires host specificity tests to estimate potential non-target impacts of a prospective agent. Currently, the approach is conservative, and is based on physiological host ranges determined under captive rearing conditions, without consideration for ecological factors that may influence realized host range. We use historical data and current field data from introduced parasitoids that attack an endemic Lepidoptera species in Hawaii to validate a probabilistic risk assessment (PRA procedure for non-target impacts. We use data on known host range and habitat use in the place of origin of the parasitoids to determine whether contemporary levels of non-target parasitism could have been predicted using PRA. Our results show that reasonable predictions of potential non-target impacts may be made if comprehensive data are available from places of origin of biological control agents, but scant data produce poor predictions. Using apparent mortality data rather than marginal attack rate estimates in PRA resulted in over-estimates of predicted non-target impact. Incorporating ecological data into PRA models improved the predictive power of the risk assessments.

Experiences with recruitment of marginalized groups in a Danish health promotion program

DEFF Research Database (Denmark)

Rasmussen, Marianne; Poulsen, Eva Kanstrup; Rytter, Anne Stoffersen

2016-01-01

neighborhoods across Denmark between 2010 and 2014. The aim of this study was to understand how recruitment approaches could promote participation in health programs within deprived neighborhoods to reach marginalized groups. METHOD: Documents from all 12 of the included municipalities were collected to conduct......BACKGROUND: Studies have found that marginalized groups living in deprived neighborhoods are less likely to participate in health programs compared to the majority of society. This study evaluates recruitment approaches conducted during a national government-funded project in 12 deprived...... have developed evaluations related to recruitment, and only three evaluations provided a description of which marginalized groups were recruited. Challenges related to recruitment consist of difficulties involving the target group, including general distrust, language barriers and a lack of ability...

The EU 20/20/2020 targets. An overview of the EMF22 assessment

Energy Technology Data Exchange (ETDEWEB)

Boehringer, Christoph [Department of Economics, Carl on Ossietzky University, Oldenburg (Germany); Rutherford, Thomas F. [Centre for Energy Policy and Economics, ETH, Zurich (Switzerland); Tol, Richard S.J. [Economic and Social Research Institute, Dublin (Ireland); Institute for Environmental Studies, Vrije Universiteit, Amsterdam (Netherlands); Department of Spatial Economics, Vrije Universiteit, Amsterdam (Netherlands)

2009-07-01

Three computable general equilibrium models are used to estimate the economic implications of a stylized version of EU climate policy. If implemented at the lowest possible cost, the 20% emissions reduction would lead to a welfare loss of 0.5-2.0% by 2020. Second-best policies increase costs. A policy with two carbon prices (one for the ETS, one for the non-ETS) could increase costs by up to 50%. A policy with 28 carbon prices (one for the ETS, one each for each Member State) could increase costs by another 40%. The renewables standard could raise the costs of emissions reduction by 90%. Overall, the inefficiencies in policy lead to a cost that is 100-125% too high. The models differ greatly in the detail of their results. The ETS/non-ETS split may have a negligible impact on welfare, while the renewables standard may even improve welfare. The models agree, however, that the distortions introduced by total EU package imply a substantial welfare loss over and above the costs needed to meet the climate target. The marginal, total and excess costs reported here are notably higher than those in the impact assessment of the European Commission. (author)

A systematic review of training interventions addressing sexual violence against marginalized at-risk groups of women.

Science.gov (United States)

Kouta, Christiana; Pithara, Christalla; Zobnina, Anna; Apostolidou, Zoe; Christodoulou, Josie; Papadakaki, Maria; Chliaoutakis, Joannes

2015-12-01

Women from marginalized groups working in occupations such as domestic work are at increased risk for sexual violence. Scarce evidence exists about training interventions targeting such groups. The article aims to identify community and workplace-based training interventions aiming to increase capacity among marginalized at-risk women to deal with sexual violence. A systematic review was applied. Inclusion criteria were English language published between 2003 and 2013; reporting on delivery and/or evaluation; focusing on any form of sexual violence; delivered to professionals, affected or at-risk women; targeting migrant, at-risk women or domestic workers. Data were extracted on the setting, content, evaluation process and target population. Four studies which focused on prevention or responding to sexual violence were included. One study provided sexual violence training to vulnerable female and one provided a HIV prevention intervention to marginalized women. Learning objectives included increasing knowledge around issues of sexual violence and/or gender and human rights, prevention and response strategies. Two studies aimed to train trainers. All studies conducted an outcome evaluation and two a process evaluation. It seems there is a gap on participatory empowerment training for marginalized women. Community train-the-trainer interventions are imperative to protect themselves and deal with the risk of sexual violence. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.

External beam radiotherapy of localized prostatic adenocarcinoma. Evaluation of conformal therapy, field number and target margins

International Nuclear Information System (INIS)

Lennernaes, B.; Rikner, G.; Letocha, H.; Nilsson, S.

1995-01-01

The purpose of the present study was to identify factors of importance in the planning of external beam radiotherapy of prostatic adenocarcinoma. Seven patients with urogenital cancers were planned for external radiotherapy of the prostate. Four different techniques were used, viz. a 4-field box technique and four-, five- or six-field conformal therapy set-ups combined with three different margins (1-3 cm). The evaluations were based on the doses delivered to the rectum and the urinary bladder. A normal tissue complication probability (NTCP) was calculated for each plan using Lyman's dose volume reduction method. The most important factors that resulted in a decrease of the dose delivered to the rectum and the bladder were the use of conformal therapy and smaller margins. Conformal therapy seemed more important for the dose distribution in the urinary bladder. Five- and six-field set-ups were not significantly better than those with four fields. NTCP calculations were in accordance with the evaluation of the dose volume histograms. To conclude, four-field conformal therapy utilizing reduced margins improves the dose distribution to the rectum and the urinary bladder in the radiotherapy of prostatic adenocarcinoma. (orig.)

Margin Evaluation in the Presence of Deformation, Rotation, and Translation in Prostate and Entire Seminal Vesicle Irradiation With Daily Marker-Based Setup Corrections

International Nuclear Information System (INIS)

Mutanga, Theodore F.; Boer, Hans C.J. de; Wielen, Gerard J. van der; Hoogeman, Mischa S.; Incrocci, Luca; Heijmen, Ben J.M.

2011-01-01

Purpose: To develop a method for margin evaluation accounting for all measured displacements during treatment of prostate cancer. Methods and Materials: For 21 patients treated with stereographic targeting marker-based online translation corrections, dose distributions with varying margins and gradients were created. Sets of possible cumulative delivered dose distributions were simulated by moving voxels and accumulating dose per voxel. Voxel motion was simulated consistent with measured distributions of systematic and random displacements due to stereographic targeting inaccuracies, deformation, rotation, and intrafraction motion. The method of simulation maintained measured correlation of voxel motions due to organ deformation. Results: For the clinical target volume including prostate and seminal vesicles (SV), the probability that some part receives <95% of the prescribed dose, the changes in minimum dose, and volume receiving 95% of prescription dose compared with planning were 80.5% ± 19.2%, 9.0 ± 6.8 Gy, and 3.0% ± 3.7%, respectively, for the smallest studied margins (3 mm prostate, 5 mm SV) and steepest dose gradients. Corresponding values for largest margins (5 mm prostate, 8 mm SV) with a clinical intensity-modulated radiotherapy dose distribution were 46.5% ± 34.7%, 6.7 ± 5.8 Gy, and 1.6% ± 2.3%. For prostate-only clinical target volume, the values were 51.8% ± 17.7%, 3.3 ± 1.6 Gy, and 0.6% ± 0.5% with the smallest margins and 5.2% ± 7.4%, 1.8 ± 0.9 Gy, and 0.1% ± 0.1% for the largest margins. Addition of three-dimensional rotation corrections only improved these values slightly. All rectal planning constraints were met in the actual reconstructed doses for all studied margins. Conclusion: We developed a system for margin validation in the presence of deformations. In our population, a 5-mm margin provided sufficient dosimetric coverage for the prostate. In contrast, an 8-mm SV margin was still insufficient owing to deformations. Addition of

"Resuscitation" of marginal liver allografts for transplantation with machine perfusion technology.

Science.gov (United States)

Graham, Jay A; Guarrera, James V

2014-08-01

As the rate of medically suitable donors remains relatively static worldwide, clinicians have looked to novel methods to meet the ever-growing demand of the liver transplant waiting lists worldwide. Accordingly, the transplant community has explored many strategies to offset this deficit. Advances in technology that target the ex vivo "preservation" period may help increase the donor pool by augmenting the utilization and improving the outcomes of marginal livers. Novel ex vivo techniques such as hypothermic, normothermic, and subnormothermic machine perfusion may be useful to "resuscitate" marginal organs by reducing ischemia/reperfusion injury. Moreover, other preservation techniques such as oxygen persufflation are explored as they may also have a role in improving function of "marginal" liver allografts. Currently, marginal livers are frequently discarded or can relegate the patient to early allograft dysfunction and primary non-function. Bench to bedside advances are rapidly emerging and hold promise for expanding liver transplantation access and improving outcomes. Copyright © 2014 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.

Safety margins in older adults increase with improved control of a dynamic object

Science.gov (United States)

Hasson, Christopher J.; Sternad, Dagmar

2014-01-01

Older adults face decreasing motor capabilities due to pervasive neuromuscular degradations. As a consequence, errors in movement control increase. Thus, older individuals should maintain larger safety margins than younger adults. While this has been shown for object manipulation tasks, several reports on whole-body activities, such as posture and locomotion, demonstrate age-related reductions in safety margins. This is despite increased costs for control errors, such as a fall. We posit that this paradox could be explained by the dynamic challenge presented by the body or also an external object, and that age-related reductions in safety margins are in part due to a decreased ability to control dynamics. To test this conjecture we used a virtual ball-in-cup task that had challenging dynamics, yet afforded an explicit rendering of the physics and safety margin. The hypotheses were: (1) When manipulating an object with challenging dynamics, older adults have smaller safety margins than younger adults. (2) Older adults increase their safety margins with practice. Nine young and 10 healthy older adults practiced moving the virtual ball-in-cup to a target location in exactly 2 s. The accuracy and precision of the timing error quantified skill, and the ball energy relative to an escape threshold quantified the safety margin. Compared to the young adults, older adults had increased timing errors, greater variability, and decreased safety margins. With practice, both young and older adults improved their ability to control the object with decreased timing errors and variability, and increased their safety margins. These results suggest that safety margins are related to the ability to control dynamics, and may explain why in tasks with simple dynamics older adults use adequate safety margins, but in more complex tasks, safety margins may be inadequate. Further, the results indicate that task-specific training may improve safety margins in older adults. PMID:25071566

Safety Margins in Older Adults Increase with Improved Control of a Dynamic Object

Directory of Open Access Journals (Sweden)

Christopher James Hasson

2014-07-01

Full Text Available Older adults face decreasing motor capabilities due to pervasive neuromuscular degradations. As a consequence errors in movement control increase. Thus, older individuals should maintain larger safety margins than younger adults. While this has been shown for object manipulation tasks, several reports on whole-body activities, such as posture and locomotion, however demonstrate age-related reductions in safety margins. This is despite increased costs for control errors, such as a fall. We posit that this paradox could be explained by the dynamic challenge presented by the body or an external object, and that age-related reductions in safety margins are in part due to a decreased ability to control dynamics. To test this conjecture we used a virtual ball-in-cup task that had challenging dynamics, yet afforded an explicit rendering of the physics and safety margin. The hypotheses were: 1 When manipulating an object with challenging dynamics, older adults have smaller safety margins than younger adults. 2 Older adults increase their safety margins with practice. Nine young and 10 healthy older adults practiced moving the virtual ball-in-cup to a target location in exactly two seconds. The accuracy and precision of the timing error quantified skill and the ball energy relative to an escape threshold quantified the safety margin. Compared to the young adults, older adults had increased timing errors, greater variability, and decreased safety margins. With practice, both young and older adults improved their ability to control the object with decreased timing errors and variability, and increased their safety margins. These results suggest that safety margins are related to the ability to control dynamics, and may explain why in tasks with simple dynamics older adults use adequate safety margins, but in more complex tasks, safety margins may be inadequate. Further, the results indicate that task-specific training may improve safety margins in older

An Investigation of Rotorcraft Stability-Phase Margin Requirements in Hover

Science.gov (United States)

Blanken, Chris L.; Lusardi, Jeff A.; Ivler, Christina M.; Tischler, Mark B.; Hoefinger, Marc T.; Decker, William A.; Malpica, Carlos A.; Berger, Tom; Tucker, George E.

2009-01-01

A cooperative study was performed to investigate the handling quality effects from reduced flight control system stability margins, and the trade-offs with higher disturbance rejection bandwidth (DRB). The piloted simulation study, perform on the NASA-Ames Vertical Motion Simulator, included three classes of rotorcraft in four configurations: a utility-class helicopter; a medium-lift helicopter evaluated with and without an external slung load; and a large (heavy-lift) civil tiltrotor aircraft. This large aircraft also allowed an initial assessment of ADS-33 handling quality requirements for an aircraft of this size. Ten experimental test pilots representing the U.S. Army, Marine Corps, NASA, rotorcraft industry, and the German Aerospace Center (DLR), evaluated the four aircraft configurations, for a range of flight control stability-margins and turbulence levels, while primarily performing the ADS-33 Hover and Lateral Reposition MTEs. Pilot comments and aircraft-task performance data were analyzed. The preliminary stability margin results suggest higher DRB and less phase margin cases are preferred as the aircraft increases in size. Extra care will need to be taken to assess the influence of variability when nominal flight control gains start with reduced margins. Phase margins as low as 20-23 degrees resulted in low disturbance-response damping ratios, objectionable oscillations, PIO tendencies, and a perception of an incipient handling qualities cliff. Pilot comments on the disturbance response of the aircraft correlated well to the DRB guidelines provided in the ADS-33 Test Guide. The A D-3S3 mid-term response-to-control damping ratio metrics can be measured and applied to the disturbance-response damping ratio. An initial assessment of LCTR yaw bandwidth shows the current Level 1 boundary needs to be relaxed to help account for a large pilot off-set from the c.g. Future efforts should continue to investigate the applicability/refinement of the current ADS-33

Energy system analysis of marginal electricity supply in consequential LCA

DEFF Research Database (Denmark)

Lund, Henrik; Mathiesen, Brian Vad; Christensen, Per

2010-01-01

Background, aim and scope This paper discusses the identification of the environmental consequences of marginal electricity supplies in consequential life cycle assessments (LCA). According to the methodology, environmental characteristics can be examined by identifying affected activities, i...... in capacity but can be characterised as a complex set of affected electricity and heat supply technologies. A long-term YAM technology is identified for the Danish BAU2030 system in the case of three different long-term marginal changes in capacity, namely coal, natural gas or wind power. Discussion Four...... of four different situations are provided. We suggest that the technology mix with the installation of natural gas or coal power plant is applied as the marginal capacity. Conclusions The environmental consequences of marginal changes in electricity supply cannot always be represented solely by long...

Assessing the efficiency of priorities for traffic law enforcement in Norway

DEFF Research Database (Denmark)

Elvik, Rune; Sogge, Céline Vallet; Lager, Lasse

2012-01-01

attributable to them; and (3) an optimal level of enforcement is selected, i.e. the marginal benefits of enforcement in terms of preventing accidents equal the marginal costs of enforcement. The efficiency of current traffic law enforcement in Norway is assessed in terms of these criteria. It is found......This paper assesses the efficiency of priorities for traffic law enforcement in Norway. Priorities are regarded as efficient if: (1) enforcement ensures a sufficient level of deterrence to keep down the rate of violations; (2) selection of target violations for enforcement is based on the risk...... low. Cost-benefit analyses show that substantially increasing the amount of police enforcement is cost-effective....

Relief for marginal wells is better than energy tax. [United States: policy

Energy Technology Data Exchange (ETDEWEB)

Swords, J.; Wilson, D. (Coopers and Lybrand (United States))

1993-04-01

By increasing production costs and reducing petroleum prices, President Bill Clinton's proposed energy tax would increase marginal well abandonments and hasten the decline of the US oil and gas industry. Instead, the US needs tax law changes to help counteract the increasing number of oil and gas well abandonments in the lower 48 states. The proposed tax would create potential difficulties, while three incentives could be introduced to reduce abandonments and at the same time preserve US government tax revenues that otherwise would be lost. Eliminating the net income limitation on percentage depletion allowances on wells that would otherwise be abandoned would be a great help for marginal well operators. Extended enhanced oil recovery (EOR) credits and broader investment tax credits could also serve the dual purpose of keeping marginal wells operating longer and generating more federal tax revenues. A marginal well investment tax credit should be provided that is not just a credit for incremented investments that exceed investment in prior years. An investment tax credit based on out-of-pocket costs of production, targeted for marginal wells, would be an important incentive to invest in, and continue to maintain, these properties. (author)

Outcomes and Patterns of Failure for Grade 2 Meningioma Treated With Reduced-Margin Intensity Modulated Radiation Therapy

Energy Technology Data Exchange (ETDEWEB)

Press, Robert H. [Department of Radiation Oncology, Emory University, Atlanta, Georgia (United States); Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Prabhu, Roshan S., E-mail: roshansprabhu@gmail.com [Department of Radiation Oncology, Emory University, Atlanta, Georgia (United States); Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Appin, Christina L.; Brat, Daniel J. [Department of Pathology, Emory University, Atlanta, Georgia (United States); Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Shu, Hui-Kuo G. [Department of Radiation Oncology, Emory University, Atlanta, Georgia (United States); Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Hadjipanayis, Constantinos; Olson, Jeffrey J.; Oyesiku, Nelson M. [Department of Neurosurgery, Emory University, Atlanta, Georgia (United States); Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Curran, Walter J.; Crocker, Ian [Department of Radiation Oncology, Emory University, Atlanta, Georgia (United States); Winship Cancer Institute, Emory University, Atlanta, Georgia (United States)

2014-04-01

Purpose: The purpose of this study was to evaluate intracranial control and patterns of local recurrence (LR) for grade 2 meningiomas treated with intensity modulated radiation therapy (IMRT) with limited total margin expansions of ≤1 cm. Methods and Materials: We reviewed records of patients with a neuropathological diagnosis of grade 2 meningioma who underwent IMRT at our institution between 2002 and 2012. Actuarial rates were determined by the Kaplan-Meier method from the end of RT. LR was defined as in-field if ≥90% of the recurrence was within the prescription isodose, out-of-field (marginal) if ≥90% was outside of the prescription isodose, and both if neither criterion was met. Results: Between 2002 and 2012, a total of 54 consecutive patients underwent IMRT for grade 2 meningioma. Eight of these patients had total initial margins >1 cm and were excluded, leaving 46 patients for analysis. The median imaging follow-up period was 26.2 months (range, 7-107 months). The median dose for fractionated IMRT was 59.4 Gy (range, 49.2-61.2 Gy). Median clinical target volume (CTV), planning target volume (PTV), and total margin expansion were 0.5 cm, 0.3 cm, and 0.8 cm, respectively. LR occurred in 8 patients (17%), with 2-year and 3-year actuarial local control (LC) of 92% and 74%, respectively. Six of 8 patients (85%) had a known pattern of failure. Five patients (83%) had in-field LR; no patients had marginal LR; and 1 patient (17%) had both. Conclusions: The use of IMRT to treat grade 2 meningiomas with total initial margins (CTV + PTV) ≤1 cm did not appear to compromise outcomes or increase marginal failures compared with other modern retrospective series. Of the 46 patients who had margins ≤1 cm, none experienced marginal failure only. These results demonstrate efficacy and low risk of marginal failure after IMRT treatment of grade 2 meningiomas with reduced margins, warranting study within a prospective clinical trial.

Medium-term marginal costs in competitive generation power markets

International Nuclear Information System (INIS)

Reneses, J.; Centeno, E.; Barquin, J.

2004-01-01

The meaning and significance of medium-term marginal costs for a generation company in a competitive power market in analysed. A methodology to compute and decompose medium-term generation marginal costs in a competitive environment is proposed. The methodology is based on a market equilibrium model. The aim is to provide a useful tool for generation companies so that they can manage their resources in an optimal way, helping them with their operation, decision-making processes, asset valuations or contract assessments. (author)

WE-AB-207B-09: Margin Reduction for Planning Target Volume (PTV) in Patients with Localized Prostate Cancer: Impact On Delivered Dose and Quality of Life

Energy Technology Data Exchange (ETDEWEB)

Kumarasiri, A; Liu, C; Brown, S; Glide-Hurst, C; Elshaikh, M; Chetty, I; Movsas, B [Henry Ford Health System, Detroit, MI (United States)

2016-06-15

Purpose: To estimate the delivered (cumulative) dose to targets and organs at risk for localized prostate cancer patients treated with reduced PTV margins and to evaluate preliminary patient reported quality-of-life (QOL). Methods: Under an IRB-approved protocol, 20 prostate cancer patients (including 11 control patients) were treated with reduced planning margins (5 mm uniform with 4 mm at prostate/rectum interface). Control patients had standard margin (10/6 mm)-based treatments. A parameter-optimized Elastix algorithm along with energy-mass mapping was used to deform and resample dose of the day onto the planning CT for each fraction to estimate the delivered dose over all fractions. QOL data were collected via Expanded Prostate cancer Index Composite (EPIC-26) questionnaires at time points pre-treatment, post-treatment, and at 2, 6, 12, 18 month follow-ups. Standardized QOL scores [range: 0–100] were determined and baseline-corrected by subtracting pre-treatment QOL data. Mean QOL differences between the margin reduced group and control group (QOLmr-QOLcontrol) were calculated for first 18 months. Results: The difference between the cumulative mean dose (Dmean) and the planned mean dose (±SD) for PTV, prostate, bladder, and rectum were −2.2±1.0, 0.3±0.5, −0.7±2.6, and −2.1±1.3 Gy respectively for the margin-reduced group, and −0.8±2.0, 0.9±1.4, - 0.7±3.1 and −1.0±2.4 Gy for the control group. Difference between the two groups was statistically insignificant (p=0.1). Standardized and baseline corrected QOLmr-QOLcontrol for EPIC domains categorized as “Urinary Incontinence”, “Urinary Irritative/Obstructive”, “Bowel”, “Sexual”, and “Hormonal” were 0.6, 12.1, 9.1, 13.3, and −0.9 for the 18 months following radiation therapy (higher values better). Delivered dose to rectum showed a weak correlation to “Bowel” domain (Pearson’s coefficient −0.24, p<0.001), while bladder dose did not correlate to Urinary Incontinence

WE-AB-207B-09: Margin Reduction for Planning Target Volume (PTV) in Patients with Localized Prostate Cancer: Impact On Delivered Dose and Quality of Life

International Nuclear Information System (INIS)

Kumarasiri, A; Liu, C; Brown, S; Glide-Hurst, C; Elshaikh, M; Chetty, I; Movsas, B

2016-01-01

Purpose: To estimate the delivered (cumulative) dose to targets and organs at risk for localized prostate cancer patients treated with reduced PTV margins and to evaluate preliminary patient reported quality-of-life (QOL). Methods: Under an IRB-approved protocol, 20 prostate cancer patients (including 11 control patients) were treated with reduced planning margins (5 mm uniform with 4 mm at prostate/rectum interface). Control patients had standard margin (10/6 mm)-based treatments. A parameter-optimized Elastix algorithm along with energy-mass mapping was used to deform and resample dose of the day onto the planning CT for each fraction to estimate the delivered dose over all fractions. QOL data were collected via Expanded Prostate cancer Index Composite (EPIC-26) questionnaires at time points pre-treatment, post-treatment, and at 2, 6, 12, 18 month follow-ups. Standardized QOL scores [range: 0–100] were determined and baseline-corrected by subtracting pre-treatment QOL data. Mean QOL differences between the margin reduced group and control group (QOLmr-QOLcontrol) were calculated for first 18 months. Results: The difference between the cumulative mean dose (Dmean) and the planned mean dose (±SD) for PTV, prostate, bladder, and rectum were −2.2±1.0, 0.3±0.5, −0.7±2.6, and −2.1±1.3 Gy respectively for the margin-reduced group, and −0.8±2.0, 0.9±1.4, - 0.7±3.1 and −1.0±2.4 Gy for the control group. Difference between the two groups was statistically insignificant (p=0.1). Standardized and baseline corrected QOLmr-QOLcontrol for EPIC domains categorized as “Urinary Incontinence”, “Urinary Irritative/Obstructive”, “Bowel”, “Sexual”, and “Hormonal” were 0.6, 12.1, 9.1, 13.3, and −0.9 for the 18 months following radiation therapy (higher values better). Delivered dose to rectum showed a weak correlation to “Bowel” domain (Pearson’s coefficient −0.24, p<0.001), while bladder dose did not correlate to Urinary Incontinence

Modification of prostate implants based on postimplant treatment margin assessment.

Science.gov (United States)

Mueller, Amy; Wallner, Kent; Merrick, Gregory; Courveau, Jacques; Sutlief, Steven; Butler, Wayne; Gong, Lixin; Cho, Paul

2002-12-01

To quantify the extent of additional source placement needed to perfect an implant after execution by standard techniques, assuming that uniform 5 mm treatment margins (TMs) is the criteria for perfection. Ten consecutive, unselected patients treated with 1-125 brachytherapy were studied. Source placement is planned just inside or outside of the prostatic margin, to achieve a minimum 5 mm TM and a central dose of 150%-200% of the prescription dose. The preimplant prostate volumes ranged from 24 to 85 cc (median: 35 cc). The number of sources implanted ranged from 48 to 102 (median: 63). Axial CT images were acquired within 2 h postoperatively for postimplant dosimetry. After completion of standard dosimetric calculations, the TMs were measured and tabulated at 45 degrees intervals around the prostate periphery at 0.0, 1.0, 2.0, and 3.0 cm planes. Sources were then added to the periphery to bring the TMs to a minimum of 5 mm at each measured TM, resulting in a modified implant. All margin modifications were done manually, without the aid of automated software. Patients' original (unmodified) D90s ranged from 111% to 154%, with a median of 116%. The original V100s ranged from 94% to 99%, with a median of 96%. No patient required placement of additional sources to meet a minimum D90 of 90% or a minimum V100 of 80%. In contrast, patients required from 7 to 17 additional sources (median: 11) to achieve minimum 5 mm TMs around the entire prostatic periphery. Additional sources equaled from 12% to 24% of the initial number of sources placed (median: 17%). By adding sufficient peripheral sources to bring the TMs to a minimum 5 mm, patients' average V100 increased from 96% to 100%, and the average D90 increased from 124% to 160% of prescription dose. In the course of achieving a minimum 5 mm TM, the average treatment margin for all patients combined increased from 5.5 to 9.9 mm. The number of sources needed to bring the TMs to a minimum 5 mm was loosely correlated with the

Modification of prostate implants based on postimplant treatment margin assessment

International Nuclear Information System (INIS)

Mueller, Amy; Wallner, Kent; Merrick, Gregory; Couriveau, Jacques; Sutlief, Steven; Butler, Wayne; Gong, Lixin; Cho, Paul

2002-01-01

Purpose: To quantify the extent of additional source placement needed to perfect an implant after execution by standard techniques, assuming that uniform 5 mm treatment margins (TMs) is the criteria for perfection. Materials and Methods: Ten consecutive, unselected patients treated with I-125 brachytherapy were studied. Source placement is planned just inside or outside of the prostatic margin, to achieve a minimum 5 mm TM and a central dose of 150%-200% of the prescription dose. The preimplant prostate volumes ranged from 24 to 85 cc (median: 35 cc). The number of sources implanted ranged from 48 to 102 (median: 63). Axial CT images were acquired within 2 h postoperatively for postimplant dosimetry. After completion of standard dosimetric calculations, the TMs were measured and tabulated at 45 deg. intervals around the prostate periphery at 0.0, 1.0, 2.0, and 3.0 cm planes. Sources were then added to the periphery to bring the TMs to a minimum of 5 mm at each measured TM, resulting in a modified implant. All margin modifications were done manually, without the aid of automated software. Results: Patients' original (unmodified) D90s ranged from 111% to 154%, with a median of 116%. The original V100s ranged from 94% to 99%, with a median of 96%. No patient required placement of additional sources to meet a minimum D90 of 90% or a minimum V100 of 80%. In contrast, patients required from 7 to 17 additional sources (median: 11) to achieve minimum 5 mm TMs around the entire prostatic periphery. Additional sources equaled from 12% to 24% of the initial number of sources placed (median: 17%). By adding sufficient peripheral sources to bring the TMs to a minimum 5 mm, patients' average V100 increased from 96% to 100%, and the average D90 increased from 124% to 160% of prescription dose. In the course of achieving a minimum 5 mm TM, the average treatment margin for all patients combined increased from 5.5 to 9.9 mm. The number of sources needed to bring the TMs to a minimum

Quality Assessment of Medical Apps that Target Medication-Related Problems.

Science.gov (United States)

Loy, John Shiguang; Ali, Eskinder Eshetu; Yap, Kevin Yi-Lwern

2016-10-01

The advent of smartphones has enabled a plethora of medical apps for disease management. As of 2012, there are 40,000 health care-related mobile apps available in the market. Since most of these medical apps do not go through any stringent quality assessment, there is a risk of consumers being misinformed or misled by unreliable information. In this regard, apps that target medication-related problems (MRPs) are not an exception. There is little information on what constitutes quality in apps that target MRPs and how good the existing apps are. To develop a quality assessment tool for evaluating apps that target MRPs and assess the quality of such apps available in the major mobile app stores (iTunes and Google Play). The top 100 free and paid apps in the medical categories of iTunes and Google Play stores (total of 400 apps) were screened for inclusion in the final analysis. English language apps that targeted MRPs were downloaded on test devices to evaluate their quality. Apps intended for clinicians, patients, or both were eligible for evaluation. The quality assessment tool consisted of 4 sections (appropriateness, reliability, usability, privacy), which determined the overall quality of the apps. Apps that fulfilled the inclusion criteria were classified based on the presence of any 1 or more of the 5 features considered important for apps targeting MRPs (monitoring, interaction checker, dose calculator, medication information, medication record). Descriptive statistics and Mann-Whitney tests were used for analysis. Final analysis was based on 59 apps that fulfilled the study inclusion criteria. Apps with interaction checker (66.9%) and monitoring features (54.8%) had the highest and lowest overall qualities. Paid apps generally scored higher for usability than free apps (P = 0.006) but lower for privacy (P = 0.003). Half of the interaction checker apps were unable to detect interactions with herbal medications. Blood pressure and heart rate monitoring apps

"We call ourselves marginalized"

DEFF Research Database (Denmark)

Jørgensen, Nanna Jordt

2014-01-01

of the people we refer to as marginalized. In this paper, I discuss how young secondary school graduates from a pastoralist community in Kenya use and negotiate indigeneity, marginal identity, and experiences of marginalization in social navigations aimed at broadening their current and future opportunities. I...

Using Logistic Approximations of Marginal Trace Lines to Develop Short Assessments

Science.gov (United States)

Stucky, Brian D.; Thissen, David; Edelen, Maria Orlando

2013-01-01

Test developers often need to create unidimensional scales from multidimensional data. For item analysis, "marginal trace lines" capture the relation with the general dimension while accounting for nuisance dimensions and may prove to be a useful technique for creating short-form tests. This article describes the computations needed to obtain…

Continental transform margins : state of art and future milestones

Science.gov (United States)

Basile, Christophe

2010-05-01

to be emphasized. There is not only one type of transform margins, but as for divergent margins huge changes from one margin to another in both structure and evolution. Multiple types have to be evidenced together with the various parameters that should control the variability. As for divergent margins, special attention should be paid to conjugated transform margins as a tool to assess symmetrical / asymmetrical processes in the oceanic opening. Attention should also be focused on the three-dimensional structure of the intersections between transform and divergent margins, such as the one where the giant oil field Jubilee was recently discovered. There is almost no 3D data available in these area, and their structures still have to be described. An other key point to develop is the mechanical behavior of the lithosphere in and in the vicinity of transform margins. The classical behaviors (isostasy, elastic flexure) have be tested extensively. The localization of the deformation by the transform fault, and the coupling of continental and oceanic lithosphere across the transform fault have to be adressed to understand the evolution of these margins. Again as for divergent margins, new concepts are needed to explain the variations in the post-rift and post-transform subsidence, that can not always be explained by classical subsidence models. But the most remarkable advance in our understanding of transform margins may be related to the study of interactions between the lithosphere and adjacent envelops : deep interactions with the mantle, as underplating, tectonic erosion, or possible lateral crustal flow ; surficial interactions between structural evolution, erosion and sedimentation processes in transform margins may affect the topography and bathymetry, thus the oceanic circulation with possible effects on regional and global climate.

Assessment of a Targeted Trap-Neuter-Return Pilot Study in Auckland, New Zealand

Science.gov (United States)

Zito, Sarah; Vigeant, Shalsee; Dale, Arnja

2018-01-01

Simple Summary It is generally accepted that stray cats need to be managed to minimise the associated negative impacts and there is a need for effective and humane management tools. One such potential tool is trap-neuter-return (TNR), which anecdotally has been used in New Zealand to manage stray cats, but no concerted and targeted implementation of this technique has been reported, nor any formal assessments conducted. A targeted TNR (TTNR) programme for urban stray cats was implemented and assessed in one Auckland suburb. Assessment was based on the number of incoming felines; stray, unsocialised cats euthanased; unsocialised, unowned cats sterilised and returned (independently of the TTNR programme); and neonatal/underage euthanasias. Incoming stray feline, underage euthanasia, and unsocialised stray cat euthanasia numbers all reduced for the targeted suburb when these outcome measures were compared for the years before and after the programme. These outcome measures had a greater reduction in the targeted suburb compared to the other Auckland suburbs not targeted by the TTNR programme, although causation cannot be inferred, as a variety of reasons could have contributed to the changes. This pilot programme suggests that TTNR could be a valuable humane cat management tool in urban New Zealand, and further assessment is warranted. Abstract There is a need for effective and humane management tools to manage urban stray cats and minimise negative impacts associated with stray cats. One such tool is targeted trap-neuter-return (TTNR), but no concerted implementation of this technique or formal assessments have been reported. To address this deficit, a TTNR programme was implemented and assessed in one Auckland suburb from May 2015 to June 2016; the programme sterilised and returned 348 cats (4.2 cats/1000 residents). Assessment was based on the number of incoming felines; stray, unsocialised cats euthanased; unsocialised, unowned cats sterilised and returned

Reactivity margins in heavy water moderated production reactors

International Nuclear Information System (INIS)

Benton, F.D.

1981-11-01

The design of the reactor core and components of the heavy water moderated reactors at the Savannah River Plant (SFP) can be varied to produce a number of isotopes. For the past decade, the predominant reactor core design has been the enriched-depleted lattice. In this lattice, fuel assemblies of highly enriched uranium and target assemblies of depleted uranium, which produce plutonium, occupy alternate lattice positions. This heterogeneous lattice arrangement and a nonuniform control rod distribution result in a reactor core that requires sophisticated calculational methods for accurate reactivity margin and power distribution predictions. For maximum accuracy, techniques must exist to provide a base of observed data for the calculations. Frequent enriched-depleted lattice design changes are required as product demands vary. These changes provided incentive for the development of techniques to combine the results of calculations and observed reactivity data to accurately and conveniently monitor reactivity margins during operation

Marginal Matter

Science.gov (United States)

van Hecke, Martin

2013-03-01

All around us, things are falling apart. The foam on our cappuccinos appears solid, but gentle stirring irreversibly changes its shape. Skin, a biological fiber network, is firm when you pinch it, but soft under light touch. Sand mimics a solid when we walk on the beach but a liquid when we pour it out of our shoes. Crucially, a marginal point separates the rigid or jammed state from the mechanical vacuum (freely flowing) state - at their marginal points, soft materials are neither solid nor liquid. Here I will show how the marginal point gives birth to a third sector of soft matter physics: intrinsically nonlinear mechanics. I will illustrate this with shock waves in weakly compressed granular media, the nonlinear rheology of foams, and the nonlinear mechanics of weakly connected elastic networks.

Marginalization of the Youth

DEFF Research Database (Denmark)

Jensen, Niels Rosendal

2009-01-01

The article is based on a key note speach in Bielefeld on the subject "welfare state and marginalized youth", focusing upon the high ambition of expanding schooling in Denmark from 9 to 12 years. The unintended effect may be a new kind of marginalization.......The article is based on a key note speach in Bielefeld on the subject "welfare state and marginalized youth", focusing upon the high ambition of expanding schooling in Denmark from 9 to 12 years. The unintended effect may be a new kind of marginalization....

Convexity and Marginal Vectors

NARCIS (Netherlands)

van Velzen, S.; Hamers, H.J.M.; Norde, H.W.

2002-01-01

In this paper we construct sets of marginal vectors of a TU game with the property that if the marginal vectors from these sets are core elements, then the game is convex.This approach leads to new upperbounds on the number of marginal vectors needed to characterize convexity.An other result is that

Evaluation of Peritumoral Edema in the Delineation of Radiotherapy Clinical Target Volumes for Glioblastoma

International Nuclear Information System (INIS)

Chang, Eric L.; Akyurek, Serap; Avalos, Tedde C; Rebueno, Neal C; Spicer, Chris C; Garcia, John C; Famiglietti, Robin; Allen, Pamela K.; Chao, K.S. Clifford; Mahajan, Anita; Woo, Shiao Y.; Maor, Moshe H.

2007-01-01

Purpose: To evaluate the spatial relationship between peritumoral edema and recurrence pattern in patients with glioblastoma (GBM). Methods and Materials: Forty-eight primary GBM patients received three-dimensional conformal radiotherapy that did not intentionally include peritumoral edema within the clinical target volume between July 2000 and June 2001. All 48 patients have subsequently recurred, and their original treatment planning parameters were used for this study. New theoretical radiation treatment plans were created for the same 48 patients, based on Radiation Therapy Oncology Group (RTOG) target delineation guidelines that specify inclusion of peritumoral edema. Target volume and recurrent tumor coverage, as well as percent volume of normal brain irradiated, were assessed for both methods of target delineation using dose-volume histograms. Results: A comparison between the location of recurrent tumor and peritumoral edema volumes from all 48 cases failed to show correlation by linear regression modeling (r 2 0.0007; p = 0.3). For patients with edema >75 cm 3 , the percent volume of brain irradiated to 46 Gy was significantly greater in treatment plans that intentionally included peritumoral edema compared with those that did not (38% vs. 31%; p = 0.003). The pattern of failure was identical between the two sets of plans (40 central, 3 in-field, 3 marginal, and 2 distant recurrence). Conclusion: Clinical target volume delineation based on a 2-cm margin rather than on peritumoral edema did not seem to alter the central pattern of failure for patients with GBM. For patients with peritumoral edema >75 cm 3 , using a constant 2-cm margin resulted in a smaller median percent volume of brain being irradiated to 30 Gy, 46 Gy, and 50 Gy compared with corresponding theoretical RTOG plans that deliberately included peritumoral edema

Targeting Bruton tyrosine kinase with ibrutinib in relapsed/refractory marginal zone lymphoma.

Science.gov (United States)

Noy, Ariela; de Vos, Sven; Thieblemont, Catherine; Martin, Peter; Flowers, Christopher R; Morschhauser, Franck; Collins, Graham P; Ma, Shuo; Coleman, Morton; Peles, Shachar; Smith, Stephen; Barrientos, Jacqueline C; Smith, Alina; Munneke, Brian; Dimery, Isaiah; Beaupre, Darrin M; Chen, Robert

2017-04-20

Marginal zone lymphoma (MZL) is a heterogeneous B-cell malignancy for which no standard treatment exists. MZL is frequently linked to chronic infection, which may induce B-cell receptor (BCR) signaling, resulting in aberrant B-cell survival and proliferation. We conducted a multicenter, open-label, phase 2 study to evaluate the efficacy and safety of ibrutinib in previously treated MZL. Patients with histologically confirmed MZL of all subtypes who received ≥1 prior therapy with an anti-CD20 antibody-containing regimen were treated with 560 mg ibrutinib orally once daily until progression or unacceptable toxicity. The primary end point was independent review committee-assessed overall response rate (ORR) by 2007 International Working Group criteria. Among 63 enrolled patients, median age was 66 years (range, 30-92). Median number of prior systemic therapies was 2 (range, 1-9), and 63% received ≥1 prior chemoimmunotherapy. In 60 evaluable patients, ORR was 48% (95% confidence interval [CI], 35-62). With median follow-up of 19.4 months, median duration of response was not reached (95% CI, 16.7 to not estimable), and median progression-free survival was 14.2 months (95% CI, 8.3 to not estimable). Grade ≥3 adverse events (AEs; >5%) included anemia, pneumonia, and fatigue. Serious AEs of any grade occurred in 44%, with grade 3-4 pneumonia being the most common (8%). Rates of discontinuation and dose reductions due to AEs were 17% and 10%, respectively. Single-agent ibrutinib induced durable responses with a favorable benefit-risk profile in patients with previously treated MZL, confirming the role of BCR signaling in this malignancy. As the only approved therapy, ibrutinib provides a treatment option without chemotherapy for MZL. This study is registered at www.clinicaltrials.gov as #NCT01980628. © 2017 by The American Society of Hematology.

Contributions to knowledge of the continental margin of Uruguay. Uruguayan continental margin: Physiographic and seismic analysis

International Nuclear Information System (INIS)

Preciozzi, F

2014-01-01

This work is about the kind of continental margins such as a )Atlantic type passive margins which can be hard or soft b) An active or Pacific margins that because of the very frequent earthquakes develop a morphology dominated by tectonic processes. The Uruguayan continental margin belongs to a soft Atlantic margin

Is popularity associated with aggression toward socially preferred or marginalized targets?

Science.gov (United States)

Peets, Kätlin; Hodges, Ernest V E

2014-08-01

This study was designed to test whether aggression toward easy or challenging targets is more likely to be associated with popularity. More specifically, we tested two alternative hypotheses with a sample of 224 adolescents (12- and 13-year-olds): (a) whether aggression toward highly disliked peers is associated with popularity (the easy target hypothesis) or (b) whether aggression toward highly liked peers is associated with popularity (the challenging target hypothesis). Support was found only for the challenging target hypothesis. In particular, our results indicate that aggressiveness toward peers who are liked by many others has social benefits in the form of greater popularity (particularly for highly preferred adolescents) without social costs (i.e., is unrelated to social preference). In contrast, aggressiveness toward peers who are disliked by many others is associated with lower social preference but bears no association with popularity. These results highlight the importance of studying contextualized aggression in order to understand the conditions under which aggression is most, and least, likely to be associated with social power and dominance. Copyright © 2014 Elsevier Inc. All rights reserved.

SOCIAL MARGINALIZATION AND HEALTH

Directory of Open Access Journals (Sweden)

Marjana Bogdanović

2007-04-01

Full Text Available The 20th century was characterized by special improvement in health. The aim of WHO’s policy EQUITY IN HEALTH is to enable equal accessibility and equal high quality of health care for all citizens. More or less some social groups have stayed out of many social systems even out of health care system in the condition of social marginalization. Phenomenon of social marginalization is characterized by dynamics. Marginalized persons have lack of control over their life and available resources. Social marginalization stands for a stroke on health and makes the health status worse. Low socio-economic level dramatically influences people’s health status, therefore, poverty and illness work together. Characteristic marginalized groups are: Roma people, people with AIDS, prisoners, persons with development disorders, persons with mental health disorders, refugees, homosexual people, delinquents, prostitutes, drug consumers, homeless…There is a mutual responsibility of community and marginalized individuals in trying to resolve the problem. Health and other problems could be solved only by multisector approach to well-designed programs.

Pickering seismic safety margin

International Nuclear Information System (INIS)

Ghobarah, A.; Heidebrecht, A.C.; Tso, W.K.

1992-06-01

A study was conducted to recommend a methodology for the seismic safety margin review of existing Canadian CANDU nuclear generating stations such as Pickering A. The purpose of the seismic safety margin review is to determine whether the nuclear plant has sufficient seismic safety margin over its design basis to assure plant safety. In this review process, it is possible to identify the weak links which might limit the seismic performance of critical structures, systems and components. The proposed methodology is a modification the EPRI (Electric Power Research Institute) approach. The methodology includes: the characterization of the site margin earthquake, the definition of the performance criteria for the elements of a success path, and the determination of the seismic withstand capacity. It is proposed that the margin earthquake be established on the basis of using historical records and the regional seismo-tectonic and site specific evaluations. The ability of the components and systems to withstand the margin earthquake is determined by database comparisons, inspection, analysis or testing. An implementation plan for the application of the methodology to the Pickering A NGS is prepared

Application of the Integrated Safety Assessment methodology to safety margins. Dynamic Event Trees, Damage Domains and Risk Assessment

International Nuclear Information System (INIS)

Ibánez, L.; Hortal, J.; Queral, C.; Gómez-Magán, J.; Sánchez-Perea, M.; Fernández, I.; Meléndez, E.; Expósito, A.; Izquierdo, J.M.; Gil, J.; Marrao, H.; Villalba-Jabonero, E.

2016-01-01

The Integrated Safety Assessment (ISA) methodology, developed by the Consejo de Seguridad Nuclear, has been applied to an analysis of Zion NPP for sequences with Loss of the Component Cooling Water System (CCWS). The ISA methodology proposal starts from the unfolding of the Dynamic Event Tree (DET). Results from this first step allow assessing the sequence delineation of standard Probabilistic Safety Analysis results. For some sequences of interest of the outlined DET, ISA then identifies the Damage Domain (DD). This is the region of uncertain times and/or parameters where a safety limit is exceeded, which indicates the occurrence of certain damage situation. This paper illustrates application of this concept obtained simulating sequences with MAAP and with TRACE. From information of simulation results of sequence transients belonging to the DD and the time-density probability distributions of the manual actions and of occurrence of stochastic phenomena, ISA integrates the dynamic reliability equations proposed to obtain the sequence contribution to the global Damage Exceedance Frequency (DEF). Reported results show a slight increase in the DEF for sequences investigated following a power uprate from 100% to 110%. This demonstrates the potential use of the method to help in the assessment of design modifications. - Highlights: • This paper illustrates an application of the ISA methodology to safety margins. • Dynamic Event Trees are useful tool for verifying the standard PSA Event Trees. • The ISA methodology takes into account the uncertainties in human action times. • The ISA methodology shows the Damage Exceedance Frequency increase in power uprates.

Systematic reviews: I. The correlation between laboratory tests on marginal quality and bond strength. II. The correlation between marginal quality and clinical outcome.

Science.gov (United States)

Heintze, Siegward D

2007-01-01

An accepted principle in restorative dentistry states that restorations should be placed with the best marginal quality possible to avoid postoperative sensitivity, marginal discoloration, and secondary caries. Different laboratory methods claim to predict the clinical performance of restorative materials, for example, tests of bond strength and microleakage and gap analysis. The purpose of this review was twofold: (1) find studies that correlated the results of bond strength tests with either microleakage or gap analysis for the same materials, and (2) find studies that correlated the results of microleakage and/or gaps with the clinical parameters for the same materials. Furthermore, influencing factors on the results of the laboratory tests were reviewed and assessed. For the first question, searches for studies were conducted in the MEDLINE database and IADR/AADR abtracts online with specific search and inclusion criteria. The outcome for each study was assessed on the basis of the statistical test applied in the study, and finally the number of studies with or without correlation was compiled. For the second question, results of the quantitative marginal analysis of Class V restorations published by the University of Zürich with the same test protocol and prospective clinical trials were searched that investigated the same materials for at least 2 years in Class V cavities. Pearson correlation coefficients were calculated for pooled data of materials and clinical outcome parameters such as retention loss, marginal discoloration, marginal integrity, and secondary caries. For the correlation of dye penetration and clinical outcome, studies on Class V restorations published by the same research institute were searched in MEDLINE that examined the same adhesive systems as the selected clinical trials. For the correlation bond strength/microleakage, 30 studies were included into the review, and for the correlation bond strength/gap analysis 18 studies. For both

Investigations of Spatial and Temporal Variability of Ocean and Ice Conditions in and Near the Marginal Ice Zone. The “Marginal Ice Zone Observations and Processes Experiment” (MIZOPEX) Final Campaign Summary

Energy Technology Data Exchange (ETDEWEB)

DeMott, P. J. [Colorado State Univ., Fort Collins, CO (United States); Hill, T. C.J. [Colorado State Univ., Fort Collins, CO (United States)

2016-02-01

Despite the significance of the marginal ice zones of the Arctic Ocean, basic parameters such as sea surface temperature (SST) and a range of sea-ice characteristics are still insufficiently understood in these areas, and especially so during the summer melt period. The field campaigns summarized here, identified collectively as the “Marginal Ice Zone Ocean and Ice Observations and Processes Experiment” (MIZOPEX), were funded by U.S. National Aeronautic and Space Administration (NASA) with the intent of helping to address these information gaps through a targeted, intensive observation field campaign that tested and exploited unique capabilities of multiple classes of unmanned aerial systems (UASs). MIZOPEX was conceived and carried out in response to NASA’s request for research efforts that would address a key area of science while also helping to advance the application of UASs in a manner useful to NASA for assessing the relative merits of different UASs. To further exercise the potential of unmanned systems and to expand the science value of the effort, the field campaign added further challenges such as air deployment of miniaturized buoys and coordinating missions involving multiple aircraft. Specific research areas that MIZOPEX data were designed to address include relationships between ocean skin temperatures and subsurface temperatures and how these evolve over time in an Arctic environment during summer; variability in sea-ice conditions such as thickness, age, and albedo within the marginal ice zone (MIZ); interactions of SST, salinity, and ice conditions during the melt cycle; and validation of satellite-derived SST and ice concentration fields provided by satellite imagery and models.

How does imaging frequency and soft tissue motion affect the PTV margin size in partial breast and boost radiotherapy?

International Nuclear Information System (INIS)

Harris, Emma J.; Donovan, Ellen M.; Coles, Charlotte E.; Boer, Hans C.J. de; Poynter, Andrew; Rawlings, Christine; Wishart, Gordon C.; Evans, Philip M.

2012-01-01

Purpose: This study investigates (i) the effect of verification protocols on treatment accuracy and PTV margins for partial breast and boost breast radiotherapy with short fractionation schema (15 fractions), (ii) the effect of deformation of the excision cavity (EC) on PTV margin size, (iii) the imaging dose required to achieve specific PTV margins. Methods and materials: Verification images using implanted EC markers were studied in 36 patients. Target motion was estimated for a 15 fraction partial breast regimen using imaging protocols based on on-line and off-line motion correction strategies (No Action Level (NAL) and the extended NAL (eNAL) protocols). Target motion was used to estimate a PTV margin for each protocol. To evaluate treatment errors due to deformation of the excision cavity, individual marker positions were obtained from 11 patients. The mean clip displacement and daily variation in clip position during radiotherapy were determined and the contribution of these errors to PTV margin calculated. Published imaging dose data were used to estimate total dose for each protocol. Finally the number of images required to obtain a specific PTV margin was evaluated and hence, the relationship between PTV margins and imaging dose was investigated. Results: The PTV margin required to account for excision cavity motion, varied between 10.2 and 2.4 mm depending on the correction strategy used. Average clip movement was 0.8 mm and average variation in clip position during treatment was 0.4 mm. The contribution to PTV margin from deformation was estimated to be small, less than 0.2 mm for both off-line and on-line correction protocols. Conclusion: A boost or partial breast PTV margin of ∼10 mm, is possible with zero imaging dose and workload, however, patients receiving boost radiotherapy may benefit from a margin reduction of ∼4 mm with imaging doses from 0.4 cGy to 25 cGy using an eNAL protocol. PTV margin contributions from deformation errors are likely

Assessment of Marginal Adaptation and Sealing Ability of Root Canal Sealers: An in vitro Study.

Science.gov (United States)

Remy, Vimal; Krishnan, Vineesh; Job, Tisson V; Ravisankar, Madhavankutty S; Raj, C V Renjith; John, Seena

2017-12-01

This study aims to compare the marginal adaptation and sealing ability [mineral trioxide aggregate (MTA)-Fillapex, AH Plus, Endofill sealers] of root canal sealers. In the present study, the inclusion criteria include 45 single-rooted extracted mandibular premolar teeth, with single canal and complete root formation. The sectioning of the samples was done at the cementoenamel junction using a low-speed diamond disc. Step-back technique was used to prepare root canals manually. The MTA-Fillapex, AH Plus, and Endofill sealers were the three experimental sealer groups to which 45 teeth were distributed. Under scanning electron microscope (SEM), marginal gap at sealer and root dentin interface were examined at coronal and apical halves of root canal. Among the three maximum marginal adaptations were seen with AH Plus sealer (4.10 ± 0.10) which is followed by Endofill sealer (1.44 ± 0.18) and MTA-Fillapex sealer (0.80 ± 0.22). Between the coronal and apical marginal adaptation, significant statistical difference (p = 0.001) was seen in AH Plus sealer. When a Mann-Whitney U-test was done on MTA-Fillapex sealer vs AH Plus sealer and AH Plus sealer vs Endofill sealer, there was a statistically significant difference (p marginal adaptation when compared with other sealers used. For sealing space of crown wall and main cone in root canal treatment, sealers play an important role. The other advantages of sealers are that they are used to fill voids and irregularities in root channel, secondary, lateral channels, and space between applied gutta-percha cones and also act as tripper during filling.

Scientific Ocean Drilling to Assess Submarine Geohazards along European Margins

Science.gov (United States)

Ask, M. V.; Camerlenghi, A.; Kopf, A.; Morgan, J. K.; Ocean DrillingSeismic Hazard, P. E.

2008-12-01

Submarine geohazards are some of the most devastating natural events in terms of lives lost and economic impact. Earthquakes pose a big threat to society and infrastructure, but the understanding of their episodic generation is incomplete. Tsunamis are known for their potential of striking coastlines world-wide. Other geohazards originating below the sea surface are equally dangerous for undersea structures and the coastal population: submarine landslides and volcanic islands collapse with little warning and devastating consequences. The European scientific community has a strong focus on geohazards along European and nearby continental margins, especially given their high population densities, and long historic and prehistoric record of hazardous events. For example, the Mediterranean is surrounded by very densely-populated coastline and is the World's leading holiday destination, receiving up 30% of global tourism. In addition, its seafloor is criss-crossed by hydrocarbon pipelines and telecommunication cables. However, the governing processes and recurrence intervals of geohazards are still poorly understood. Examples include, but are not limited to, earthquakes and volcanic eruptions along the active tectonic margins of the Mediterranean and Sea of Marmara, landslides on both active and passive margins, and tsunamites and seismites in the sedimentary record that suggest a long history of similar events. The development of geophysical networks, drilling, sampling and long-term monitoring are crucial to the understanding of earthquake, landslide, and tsunami processes, and to mitigate the associated risks in densely populated and industrialized regions such as Europe. Scientific drilling, particularly in the submarine setting, offers a unique tool to obtain drill core samples, borehole measurements and long-term observations. Hence, it is a critical technology to investigate past, present, and possible future influences of hazardous processes in this area. The

Indian Ocean margins

Digital Repository Service at National Institute of Oceanography (India)

Naqvi, S.W.A

in the latter two areas. Some of these fluxes are expected to be substantial in the case of Indonesian continental margins and probably also across the eastern coasts of Africa not covered in this chapter. However, a dearth of information makes these margins...

Comparison of Safety Margin Generation Concepts in Image Guided Radiotherapy to Account for Daily Head and Neck Pose Variations.

Science.gov (United States)

Stoll, Markus; Stoiber, Eva Maria; Grimm, Sarah; Debus, Jürgen; Bendl, Rolf; Giske, Kristina

2016-01-01

Intensity modulated radiation therapy (IMRT) of head and neck tumors allows a precise conformation of the high-dose region to clinical target volumes (CTVs) while respecting dose limits to organs a risk (OARs). Accurate patient setup reduces translational and rotational deviations between therapy planning and therapy delivery days. However, uncertainties in the shape of the CTV and OARs due to e.g. small pose variations in the highly deformable anatomy of the head and neck region can still compromise the dose conformation. Routinely applied safety margins around the CTV cause higher dose deposition in adjacent healthy tissue and should be kept as small as possible. In this work we evaluate and compare three approaches for margin generation 1) a clinically used approach with a constant isotropic 3 mm margin, 2) a previously proposed approach adopting a spatial model of the patient and 3) a newly developed approach adopting a biomechanical model of the patient. All approaches are retrospectively evaluated using a large patient cohort of over 500 fraction control CT images with heterogeneous pose changes. Automatic methods for finding landmark positions in the control CT images are combined with a patient specific biomechanical finite element model to evaluate the CTV deformation. The applied methods for deformation modeling show that the pose changes cause deformations in the target region with a mean motion magnitude of 1.80 mm. We found that the CTV size can be reduced by both variable margin approaches by 15.6% and 13.3% respectively, while maintaining the CTV coverage. With approach 3 an increase of target coverage was obtained. Variable margins increase target coverage, reduce risk to OARs and improve healthy tissue sparing at the same time.

A margin of exposure approach to assessment of non-cancerous risk of diethyl phthalate based on human exposure from bottled water consumption.

Science.gov (United States)

Zare Jeddi, Maryam; Rastkari, Noushin; Ahmadkhaniha, Reza; Yunesian, Masud; Nabizadeh, Ramin; Daryabeygi, Reza

2015-12-01

Phthalates may be present in food due to their widespread presence as environmental contaminants or due to migration from food contact materials. Exposure to phthalates is considered to be potentially harmful to human health as well. Therefore, determining the main source of exposure is an important issue. So, the purpose of this study was (1) to measure the release of diethyl phthalate (DEP) in bottled water consumed in common storage conditions specially low temperature and freezing conditions; (2) to evaluate the intake of DEP from polyethylene terephthalate (PET) bottled water and health risk assessment; and (3) to assess the contribution of the bottled water to the DEP intake against the tolerable daily intake (TDI) values. DEP migration was investigated in six brands of PET-bottled water under different storage conditions room temperature, refrigerator temperature, freezing conditions (40 °C ,0 °C and -18 °C) and outdoor] at various time intervals by magnetic solid extraction (MSPE) using gas chromatography-mass spectroscopy (GC-MS). Eventually, a health risk assessment was conducted and the margin of exposure (MOE) was calculated. The results indicate that contact time with packaging and storage temperatures caused DEP to be released into water from PET bottles. But, when comprising the DEP concentration with initial level, the results demonstrated that the release of phthalates were not substantial in all storage conditions especially at low temperatures ( children > lactating women > teenagers > adults > pregnant women), but in all target groups, the MOE was much higher than 1000, thus, low risk is implied. Consequently, PET-bottled water is not a major source of human exposure to DEP and from this perspective is safe for consumption.

Marginal kidney donor

Directory of Open Access Journals (Sweden)

Ganesh Gopalakrishnan

2007-01-01

Full Text Available Renal transplantation is the treatment of choice for a medically eligible patient with end stage renal disease. The number of renal transplants has increased rapidly over the last two decades. However, the demand for organs has increased even more. This disparity between the availability of organs and waitlisted patients for transplants has forced many transplant centers across the world to use marginal kidneys and donors. We performed a Medline search to establish the current status of marginal kidney donors in the world. Transplant programs using marginal deceased renal grafts is well established. The focus is now on efforts to improve their results. Utilization of non-heart-beating donors is still in a plateau phase and comprises a minor percentage of deceased donations. The main concern is primary non-function of the renal graft apart from legal and ethical issues. Transplants with living donors outnumbered cadaveric transplants at many centers in the last decade. There has been an increased use of marginal living kidney donors with some acceptable medical risks. Our primary concern is the safety of the living donor. There is not enough scientific data available to quantify the risks involved for such donation. The definition of marginal living donor is still not clear and there are no uniform recommendations. The decision must be tailored to each donor who in turn should be actively involved at all levels of the decision-making process. In the current circumstances, our responsibility is very crucial in making decisions for either accepting or rejecting a marginal living donor.

Systems considerations in seismic margin evaluations

International Nuclear Information System (INIS)

Buttermer, D.R.

1987-01-01

Increasing knowledge in the geoscience field has led to the understanding that, although highly unlikely, it is possible for a nuclear power plant to be subjected to earthquake ground motion greater than that for which the plant was designed. While it is recognized that there are conservatisms inherent in current design practices, interest has developed in evaluating the seismic risk of operating plants. Several plant-specific seismic probabilistic risk assessments (SPRA) have been completed to address questions related to the seismic risk of a plant. The results from such SPRAs are quite informative, but such studies may entail a considerable amount of expensive analysis of large portions of the plant. As an alternative to an SPRA, it may be more practical to select an earthquake level above the design basis for which plant survivability is to be demonstrated. The principal question to be addressed in a seismic margin evaluation is: At what ground motion levels does one have a high confidence that the probability of seismically induced core damage is sufficiently low? In a seismic margin evaluation, an earthquake level is selected (based on site-specific geoscience considerations) for which a stable, long-term safe shutdown condition is to be demonstrated. This prespecified earthquake level is commonly referred to as the seismic margin earthquake (SME). The Electric Power Research Institute is currently supporting a research project to develop procedures for use by the utilities to allow them to perform nuclear plant seismic margin evaluations. This paper describes the systems-related aspects of these procedures

Valuation of marginal CO2 abatement options for electric power plants in Korea

International Nuclear Information System (INIS)

Park, Hojeong; Lim, Jaekyu

2009-01-01

The electricity generation sector in Korea is under pressure to mitigate greenhouse gases as directed by the Kyoto Protocol. The principal compliance options for power companies under the cap-and-trade include the application of direct CO 2 emission abatement and the procurement of emission allowances. The objective of this paper is to provide an analytical framework for assessing the cost-effectiveness of these options. We attempt to derive the marginal abatement cost for CO 2 using the output distance function and analyze the relative advantages of emission allowance procurement option as compared to direct abatement option. Real-option approach is adopted to incorporate emission allowance price uncertainty. Empirical result shows the marginal abatement cost with an average of Euro 14.04/ton CO 2 for fossil-fueled power plants and confirms the existence of substantial cost heterogeneity among plants which is sufficient to achieve trading gains in allowance market. The comparison of two options enables us to identify the optimal position of the compliance for each plant. Sensitivity analyses are also presented with regard to several key parameters including the initial allowance prices and interest rate. The result of this paper may help Korean power plants to prepare for upcoming regulations targeted toward the reduction of domestic greenhouse gases.

Hippocampal sparing radiotherapy for pediatric medulloblastoma: impact of treatment margins and treatment technique.

Science.gov (United States)

Brodin, N Patrik; Munck af Rosenschöld, Per; Blomstrand, Malin; Kiil-Berthlesen, Anne; Hollensen, Christian; Vogelius, Ivan R; Lannering, Birgitta; Bentzen, Søren M; Björk-Eriksson, Thomas

2014-04-01

We investigated how varying the treatment margin and applying hippocampal sparing and proton therapy impact the risk of neurocognitive impairment in pediatric medulloblastoma patients compared with current standard 3D conformal radiotherapy. We included 17 pediatric medulloblastoma patients to represent the variability in tumor location relative to the hippocampal region. Treatment plans were generated using 3D conformal radiotherapy, hippocampal sparing intensity-modulated radiotherapy, and spot-scanned proton therapy, using 3 different treatment margins for the conformal tumor boost. Neurocognitive impairment risk was estimated based on dose-response models from pediatric CNS malignancy survivors and compared among different margins and treatment techniques. Mean hippocampal dose and corresponding risk of cognitive impairment were decreased with decreasing treatment margins (P < .05). The largest risk reduction, however, was seen when applying hippocampal sparing proton therapy-the estimated risk of impaired task efficiency (95% confidence interval) was 92% (66%-98%), 81% (51%-95%), and 50% (30%-70%) for 3D conformal radiotherapy, intensity-modulated radiotherapy, and proton therapy, respectively, for the smallest boost margin and 98% (78%-100%), 90% (60%-98%), and 70% (39%-90%) if boosting the whole posterior fossa. Also, the distance between the closest point of the planning target volume and the center of the hippocampus can be used to predict mean hippocampal dose for a given treatment technique. We estimate a considerable clinical benefit of hippocampal sparing radiotherapy. In choosing treatment margins, the tradeoff between margin size and risk of neurocognitive impairment quantified here should be considered.

Municipalities' Priority Problems and Prospect of Establishing Ordinance to Measures for Marginal Hamlets

Science.gov (United States)

Nakanishi, Mayumi; Hoshino, Satoshi; Hashimoto, Shizuka; Kuki, Yasuaki

The problems of Marginal Hamlets are getting worse, in which more than half of the population is over 65 and community-based life is difficult. To contribute to effective policy making, we conducted a questionnaire survey to members of the National Liaison Council of ‘Suigen no Sato’ constituted to share information about problems and effective counter measures for marginal hamlets. Our study clarified that first, most of respondents had common problems such as lack of job-opportunities and animal damage on farm, and second, though most of respondents recognized the effectiveness of selecting target communities in policy implementations, it is difficult for municipal governments to establish such ordinance provided that councilors and those who were not living in areas of policy target wouldn't agree with it. Finally, we pointed out the roles of national and prefectural governments to help municipal governments effectively cope with such entangled situations.

Seismic Margin of 500MWe PFBR Beyond Safe Shutdown Earthquake

International Nuclear Information System (INIS)

Sajish, S.D.; Chellapandi, P.; Chetal, S.C.

2012-01-01

Summary: • Seismic design aspects of safety related systems and components of PFBR is discussed with a focus on reactor assembly components. • PFBR is situated in a low seismic area with a peak ground acceleration value of 0.156 g. • The design basis ground motion parameters for the seismic design are evaluated by deterministic method and confirmed by probabilistic seismic hazard analysis. • Review of the seismic design of various safety related systems and components indicate that margin is available to meet any demand due to an earthquake beyond SSE. • Reactor assembly vessels are the most critical components w.r.t seismic loading. • Minimum safety margin is 1.41 for plastic deformation and 1.46 against buckling. • From the preliminary investigation we come to the conclusion that PFBR can withstand an earthquake up to 0.22 g without violating any safety limits. • Additional margin can be estimated by detailed fragility analysis and seismic margin assessment methods

The scenario-based generalization of radiation therapy margins

International Nuclear Information System (INIS)

Fredriksson, Albin; Bokrantz, Rasmus

2016-01-01

We give a scenario-based treatment plan optimization formulation that is equivalent to planning with geometric margins if the scenario doses are calculated using the static dose cloud approximation. If the scenario doses are instead calculated more accurately, then our formulation provides a novel robust planning method that overcomes many of the difficulties associated with previous scenario-based robust planning methods. In particular, our method protects only against uncertainties that can occur in practice, it gives a sharp dose fall-off outside high dose regions, and it avoids underdosage of the target in ‘easy’ scenarios. The method shares the benefits of the previous scenario-based robust planning methods over geometric margins for applications where the static dose cloud approximation is inaccurate, such as irradiation with few fields and irradiation with ion beams. These properties are demonstrated on a suite of phantom cases planned for treatment with scanned proton beams subject to systematic setup uncertainty. (paper)

Lithosphere structure and subsidence evolution of the conjugate S-African and Argentine margins

Science.gov (United States)

Dressel, Ingo; Scheck-Wenderoth, Magdalena; Cacace, Mauro; Götze, Hans-Jürgen; Franke, Dieter

2016-04-01

The bathymetric evolution of the South Atlantic passive continental margins is a matter of debate. Though it is commonly accepted that passive margins experience thermal subsidence as a result of lithospheric cooling as well as load induced subsidence in response to sediment deposition it is disputed if the South Atlantic passive margins were affected by additional processes affecting the subsidence history after continental breakup. We present a subsidence analysis along the SW African margin and offshore Argentina and restore paleobathymetries to assess the subsidence evolution of the margin. These results are discussed with respect to mechanisms behind margin evolution. Therefore, we use available information about the lithosphere-scale present-day structural configuration of these margins as a starting point for the subsidence analysis. A multi 1D backward modelling method is applied to separate individual subsidence components such as the thermal- as well as the load induced subsidence and to restore paleobathymetries for the conjugate margins. The comparison of the restored paleobathymetries shows that the conjugate margins evolve differently: Continuous subsidence is obtained offshore Argentina whereas the subsidence history of the SW African margin is interrupted by phases of uplift. This differing results for both margins correlate also with different structural configurations of the subcrustal mantle. In the light of these results we discuss possible implications for uplift mechanisms.

Test characteristics of high-resolution ultrasound in the preoperative assessment of margins of basal cell and squamous cell carcinoma in patients undergoing Mohs micrographic surgery.

Science.gov (United States)

Jambusaria-Pahlajani, Anokhi; Schmults, Chrysalyne D; Miller, Christopher J; Shin, Daniel; Williams, Jennifer; Kurd, Shanu K; Gelfand, Joel M

2009-01-01

Noninvasive techniques to assess subclinical spread of nonmelanoma skin cancer (NMSC) may improve surgical precision. High-resolution ultrasound has shown promise in evaluating the extent of NMSC. To determine the accuracy of high-resolution ultrasound to assess the margins of basal cell (BCC) and squamous cell carcinomas (SCC) before Mohs micrographic surgery (MMS). We enrolled 100 patients with invasive SCC or BCC. Before the first stage of MMS, a Mohs surgeon delineated the intended surgical margin. Subsequently, a trained ultrasound technologist independently evaluated disease extent using the EPISCAN I-200 to evaluate tumor extent beyond this margin. The accuracy of high-resolution ultrasound was subsequently tested by comparison with pathology from frozen sections. The test characteristics of the high-resolution ultrasound were sensitivity=32%, specificity=88%, positive predictive value=47%, and negative predictive value=79%. Subgroup analyses demonstrated better test characteristics for tumors larger than the median (area>1.74 cm(2)). Qualitative analyses showed that high-resolution ultrasound was less likely to identify extension from tumors with subtle areas of extension, such as small foci of dermal invasion from infiltrative SCC and micronodular BCC. High-resolution ultrasound requires additional refinements to improve the preoperative determination of tumor extent before surgical treatment of NMSC.

Comparison of 2D and 3D algorithms for adding a margin to the gross tumor volume in the conformal radiotherapy planning of prostate cancer

International Nuclear Information System (INIS)

Khoo, V.S.; Bedford, J.L.; Webb, S.; Dearnaley, D.P.

1997-01-01

Purpose: To evaluate the adequacy of tumor volume coverage using a three dimensional (3D) margin growing algorithm compared to a two dimensional (2D) margin growing algorithm in the conformal radiotherapy planning of prostate cancer. Methods and Materials: Two gross tumor volumes (GTV) were segmented in each of ten patients with localized prostate cancer: prostate gland only (PO) and prostate with seminal vesicles (PSV). A margin of 10 mm was applied to these two groups (PO and PSV) using both the 2D and 3D margin growing algorithms. The true planning target volume (PTV) was defined as the region delineated by the 3D algorithm. Adequacy of geometric coverage of the GTV with the two algorithms was examined throughout the target volume. Discrepancies between the two margin methods were measured in the transaxial plane. Results: The 2D algorithm underestimated the PTV by 17% (range 12-20) in the PO group and by 20% (range 13-28) for the PSV group when compared to the 3D algorithm. For both the PO and PSV groups, the inferior coverage of the PTV was consistently underestimated by the 2D margin algorithm when compared to the 3D margins with a mean radial distance of 4.8 mm (range 0-10). In the central region of the prostate gland, the anterior, posterior, and lateral PTV borders were underestimated with the 2D margin in both the PO and PSV groups by a mean of 3.6 mm (range 0-9), 2.1 mm (range 0-8), and 1.8 (range 0-9) respectively. The PTV coverage of the PO group superiorly was radially underestimated by 4.5mm (range 0-14) when comparing the 2D margins to the 3D margins. For the PSV group, the junction region between the prostate and the seminal vesicles was underestimated by the 2D margin by a mean transaxial distance of 18.1 mm in the anterior PTV border (range 4-30), 7.2 mm posteriorly (range 0-20), and 3.7 mm laterally (range 0-14). The superior region of the seminal vesicles in the PSV group was also consistently underestimated with a radial discrepancy of 3.3 mm

Need for a marginal methodology in assessing natural gas system methane emissions in response to incremental consumption.

Science.gov (United States)

Mac Kinnon, Michael; Heydarzadeh, Zahra; Doan, Quy; Ngo, Cuong; Reed, Jeff; Brouwer, Jacob

2018-05-17

Accurate quantification of methane emissions from the natural gas system is important for establishing greenhouse gas inventories and understanding cause and effect for reducing emissions. Current carbon intensity methods generally assume methane emissions are proportional to gas throughput so that increases in gas consumption yield linear increases in emitted methane. However, emissions sources are diverse and many are not proportional to throughput. Insights into the causal drivers of system methane emissions, and how system-wide changes affect such drivers are required. The development of a novel cause-based methodology to assess marginal methane emissions per unit of fuel consumed is introduced. The carbon intensities of technologies consuming natural gas are critical metrics currently used in policy decisions for reaching environmental goals. For example, the low-carbon fuel standard in California uses carbon intensity to determine incentives provided. Current methods generally assume methane emissions from the natural gas system are completely proportional to throughput. The proposed cause-based marginal emissions method will provide a better understanding of the actual drivers of emissions to support development of more effective mitigation measures. Additionally, increasing the accuracy of carbon intensity calculations supports the development of policies that can maximize the environmental benefits of alternative fuels, including reducing greenhouse gas emissions.

On marginal regeneration

NARCIS (Netherlands)

Stein, H.N.

1991-01-01

On applying the marginal regeneration concept to the drainage of free liquid films, problems are encountered: the films do not show a "neck" of minimum thickness at the film/border transition; and the causes of the direction dependence of the marginal regeneration are unclear. Both problems can be

Poster - 36: Effect of Planning Target Volume Coverage on the Dose Delivered in Lung Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Dekker, Chris; Wierzbicki, Marcin [McMaster University, Juravinski Cancer Centre (Canada)

2016-08-15

Purpose: In lung radiotherapy, breathing motion may be encompassed by contouring the internal target volume (ITV). Remaining uncertainties are included in a geometrical expansion to the planning target volume (PTV). In IMRT, the treatment is then optimized until a desired PTV fraction is covered by the appropriate dose. The resulting beams often carry high fluence in the PTV margin to overcome low lung density and to generate steep dose gradients. During treatment, the high density tumour can enter the PTV margin, potentially increasing target dose. Thus, planning lung IMRT with a reduced PTV dose may still achieve the desired ITV dose during treatment. Methods: A retrospective analysis was carried out with 25 IMRT plans prescribed to 63 Gy in 30 fractions. The plans were re-normalized to cover various fractions of the PTV by different isodose lines. For each case, the isocentre was moved using 125 shifts derived from all 3D combinations of 0 mm, (PTV margin - 1 mm), and PTV margin. After each shift, the dose was recomputed to approximate the delivered dose. Results and Conclusion: Our plans typically cover 95% of the PTV by 95% of the dose. Reducing the PTV covered to 94% did not significantly reduce the delivered ITV doses for (PTV margin - 1 mm) shifts. Target doses were reduced significantly for all other shifts and planning goals studied. Thus, a reduced planning goal will likely deliver the desired target dose as long as the ITV rarely enters the last mm of the PTV margin.

Preliminary assessment of interactions between the FMIT deuteron beam and liquid-lithium target

International Nuclear Information System (INIS)

Hassberger, J.A.

1983-03-01

Scoping calculations were performed to assess the limit of response of the FMIT lithium target to the deuteron-beam interactions. Results indicate that most response modes have acceptably minor impacts on the lithium-target behavior. Individual modes of response were studied separately to assess sensitivity of the target to various phenomena and to identify those needing detailed evaluation. A few responses are of sufficient magnitude to warrant further investigation. Potential for several different responses combining additively is identified as the major area requiring further consideration

Safety margins associated with containment structures under dynamic loading

International Nuclear Information System (INIS)

Lu, S.C.

1978-01-01

A technical basis for assessing the true safety margins of containment structures involved with MARK I boiling water reactor reevaluation activities is presented. It is based on the results of a plane-strain, large displacement, elasto-plastic, finite-element analysis of a thin cylindrical shell subjected to external and internal pressure pulses. An analytical procedure is presented for estimating the ultimate load capacity of the thin shell structure, and subsequently, for quantifying the design margins of safety for the type of loads under consideration. For defining failure of structures, a finite strain failure criterion is derived that accounts for multiaxiality effects

Refining margins and prospects

International Nuclear Information System (INIS)

Baudouin, C.; Favennec, J.P.

1997-01-01

Refining margins throughout the world have remained low in 1996. In Europe, in spite of an improvement, particularly during the last few weeks, they are still not high enough to finance new investments. Although the demand for petroleum products is increasing, experts are still sceptical about any rapid recovery due to prevailing overcapacity and to continuing capacity growth. After a historical review of margins and an analysis of margins by regions, we analyse refining over-capacities in Europe and the unbalances between production and demand. Then we discuss the current situation concerning barriers to the rationalization, agreements between oil companies, and the consequences on the future of refining capacities and margins. (author)

Safety margins in deterministic safety analysis

International Nuclear Information System (INIS)

Viktorov, A.

2011-01-01

The concept of safety margins has acquired certain prominence in the attempts to demonstrate quantitatively the level of the nuclear power plant safety by means of deterministic analysis, especially when considering impacts from plant ageing and discovery issues. A number of international or industry publications exist that discuss various applications and interpretations of safety margins. The objective of this presentation is to bring together and examine in some detail, from the regulatory point of view, the safety margins that relate to deterministic safety analysis. In this paper, definitions of various safety margins are presented and discussed along with the regulatory expectations for them. Interrelationships of analysis input and output parameters with corresponding limits are explored. It is shown that the overall safety margin is composed of several components each having different origins and potential uses; in particular, margins associated with analysis output parameters are contrasted with margins linked to the analysis input. While these are separate, it is possible to influence output margins through the analysis input, and analysis method. Preserving safety margins is tantamount to maintaining safety. At the same time, efficiency of operation requires optimization of safety margins taking into account various technical and regulatory considerations. For this, basic definitions and rules for safety margins must be first established. (author)

Effective collaboration between marginal metallophilic macrophages and CD8+ dendritic cells in the generation of cytotoxic T cells

Science.gov (United States)

Backer, Ronald; Schwandt, Timo; Greuter, Mascha; Oosting, Marije; Jüngerkes, Frank; Tüting, Thomas; Boon, Louis; O’Toole, Tom; Kraal, Georg; Limmer, Andreas; den Haan, Joke M. M.

2009-01-01

The spleen is the lymphoid organ that induces immune responses toward blood-borne pathogens. Specialized macrophages in the splenic marginal zone are strategically positioned to phagocytose pathogens and cell debris, but are not known to play a role in the activation of T-cell responses. Here we demonstrate that splenic marginal metallophilic macrophages (MMM) are essential for cross-presentation of blood-borne antigens by splenic dendritic cells (DCs). Our data demonstrate that antigens targeted to MMM as well as blood-borne adenoviruses are efficiently captured by MMM and exclusively transferred to splenic CD8+ DCs for cross-presentation and for the activation of cytotoxic T lymphocytes. Depletion of macrophages in the marginal zone prevents cytotoxic T-lymphocyte activation by CD8+ DCs after antibody targeting or adenovirus infection. Moreover, we show that tumor antigen targeting to MMM is very effective as antitumor immunotherapy. Our studies point to an important role for splenic MMM in the initial steps of CD8+ T-cell immunity by capturing and concentrating blood-borne antigens and the transfer to cross-presenting DCs which can be used to design vaccination strategies to induce antitumor cytotoxic T-cell immunity. PMID:20018690

Marginal Models for Categorial Data

NARCIS (Netherlands)

Bergsma, W.P.; Rudas, T.

2002-01-01

Statistical models defined by imposing restrictions on marginal distributions of contingency tables have received considerable attention recently. This paper introduces a general definition of marginal log-linear parameters and describes conditions for a marginal log-linear parameter to be a smooth

Robust Adaptation? Assessing the sensitivity of safety margins in flood defences to uncertainty in future simulations - a case study from Ireland.

Science.gov (United States)

Murphy, Conor; Bastola, Satish; Sweeney, John

2013-04-01

Climate change impact and adaptation assessments have traditionally adopted a 'top-down' scenario based approach, where information from different Global Climate Models (GCMs) and emission scenarios are employed to develop impacts led adaptation strategies. Due to the tradeoffs in the computational cost and need to include a wide range of GCMs for fuller characterization of uncertainties, scenarios are better used for sensitivity testing and adaptation options appraisal. One common approach to adaptation that has been defined as robust is the use of safety margins. In this work the sensitivity of safety margins that have been adopted by the agency responsible for flood risk management in Ireland, to the uncertainty in future projections are examined. The sensitivity of fluvial flood risk to climate change is assessed for four Irish catchments using a large number of GCMs (17) forced with three emissions scenarios (SRES A1B, A2, B1) as input to four hydrological models. Both uncertainty within and between hydrological models is assessed using the GLUE framework. Regionalisation is achieved using a change factor method to infer changes in the parameters of a weather generator using monthly output from the GCMs, while flood frequency analysis is conducted using the method of probability weighted moments to fit the Generalised Extreme Value distribution to ~20,000 annual maxima series. The sensitivity of design margins to the uncertainty space considered is visualised using risk response surfaces. The hydrological sensitivity is measured as the percentage change in flood peak for specified recurrence intervals. Results indicate that there is a considerable residual risk associated with allowances of +20% when uncertainties are accounted for and that the risk of exceedence of design allowances is greatest for more extreme, low frequency events with considerable implication for critical infrastructure, e.g., culverts, bridges, flood defences whose designs are normally

Distributions with given marginals and statistical modelling

CERN Document Server

Fortiana, Josep; Rodriguez-Lallena, José

2002-01-01

This book contains a selection of the papers presented at the meeting `Distributions with given marginals and statistical modelling', held in Barcelona (Spain), July 17-20, 2000. In 24 chapters, this book covers topics such as the theory of copulas and quasi-copulas, the theory and compatibility of distributions, models for survival distributions and other well-known distributions, time series, categorical models, definition and estimation of measures of dependence, monotonicity and stochastic ordering, shape and separability of distributions, hidden truncation models, diagonal families, orthogonal expansions, tests of independence, and goodness of fit assessment. These topics share the use and properties of distributions with given marginals, this being the fourth specialised text on this theme. The innovative aspect of the book is the inclusion of statistical aspects such as modelling, Bayesian statistics, estimation, and tests.

Close or positive margins after surgical resection for the head and neck cancer patient: the addition of brachytherapy improves local control

International Nuclear Information System (INIS)

Beitler, Jonathan J.; Smith, Richard V.; Silver, Carl E.; Quish, Astrid; Deore, Shivaji M.; Mullokandov, Eduard; Fontenla, Doracy P.; Wadler, Scott; Hayes, Mary Katherine; Vikram, Bhadrasain

1998-01-01

Purpose: Microscopically positive or close margins after surgical resection results in an approximately 21-26% local failure rate despite excellent postoperative external radiation therapy. We sought to demonstrate improved local control in head and neck cancer patients who had a resection with curative intent, and had unexpected, microscopically positive or close surgical margins. Methods and Materials: Twenty-nine patients with microscopically close or positive margins after curative surgery were given definitive, adjuvant external radiation therapy and 125 I brachytherapy. All 29 patients had squamous cell cancer and tonsil was the most common subsite within the head and neck region. After external radiation therapy and thorough discussions with the attending surgeon and pathologists, the slides, gross specimens, and appropriate radiographs were reviewed and a target volume was determined. The target volume was the region of the margin in question and varied in size based on the surgery and pathologic results. Once the target volume was identified the patient was taken back to the operating room for insertion of 125 I seeds. Activity implanted (range 2.9-21.5 millicuries) was designed to administer a cumulative lifetime dose of 120-160 Gy. Results: Twenty-nine patients were followed for a median of 26 months (range 5-86 months). Two-year actuarial local control was 92%. Conclusion: 125 I, after external radiation therapy, is an excellent method to improve local control in the subset of patients with unexpectedly unsatisfactory margins

Digital Margins : How spatially and socially marginalized communities deal with digital exclusion

NARCIS (Netherlands)

Salemink, Koen

2016-01-01

The increasing importance of the Internet as a means of communication has transformed economies and societies. For spatially and socially marginalized communities, this transformation has resulted in digital exclusion and further marginalization. This book presents a study of two kinds of

Optimal beam margins in linac-based VMAT stereotactic ablative body radiotherapy: a Pareto front analysis for liver metastases.

Science.gov (United States)

Cilla, Savino; Ianiro, Anna; Deodato, Francesco; Macchia, Gabriella; Digesù, Cinzia; Valentini, Vincenzo; Morganti, Alessio G

2017-11-27

We explored the Pareto fronts mathematical strategy to determine the optimal block margin and prescription isodose for stereotactic body radiotherapy (SBRT) treatments of liver metastases using the volumetric-modulated arc therapy (VMAT) technique. Three targets (planning target volumes [PTVs] = 20, 55, and 101 cc) were selected. A single fraction dose of 26 Gy was prescribed (prescription dose [PD]). VMAT plans were generated for 3 different beam energies. Pareto fronts based on (1) different multileaf collimator (MLC) block margin around PTV and (2) different prescription isodose lines (IDL) were produced. For each block margin, the greatest IDL fulfilling the criteria (95% of PTV reached 100%) was considered as providing the optimal clinical plan for PTV coverage. Liver D mean , V7Gy, and V12Gy were used against the PTV coverage to generate the fronts. Gradient indexes (GI and mGI), homogeneity index (HI), and healthy liver irradiation in terms of D mean , V7Gy, and V12Gy were calculated to compare different plans. In addition, each target was also optimized with a full-inverse planning engine to obtain a direct comparison with anatomy-based treatment planning system (TPS) results. About 900 plans were calculated to generate the fronts. GI and mGI show a U-shaped behavior as a function of beam margin with minimal values obtained with a +1 mm MLC margin. For these plans, the IDL ranges from 74% to 86%. GI and mGI show also a V-shaped behavior with respect to HI index, with minimum values at 1 mm for all metrics, independent of tumor dimensions and beam energy. Full-inversed optimized plans reported worse results with respect to Pareto plans. In conclusion, Pareto fronts provide a rigorous strategy to choose clinical optimal plans in SBRT treatments. We show that a 1-mm MLC block margin provides the best results with regard to healthy liver tissue irradiation and steepness of dose fallout. Copyright © 2017 American Association of Medical Dosimetrists

Test characteristics of high frequency ultrasound in the pre-operative assessment of margins of basal cell and squamous cell carcinoma in patients undergoing Mohs micrographic surgery

Science.gov (United States)

Jambusaria-Pahlajani, Anokhi; Schmults, Chrysalyne D.; Miller, Christopher J.; Shin, Daniel; Williams, Jennifer; Kurd, Shanu K; Gelfand, Joel M.

2015-01-01

Background Non-invasive techniques to assess subclinical spread of non-melanoma skin cancer (NMSC) may improve surgical precision. High frequency ultrasound (HIFU) has shown promise to evaluate the extent of NMSC. Objective To determine the accuracy of HIFU to assess the margins of basal cell (BCC) and squamous cell carcinomas (SCC) prior to Mohs micrographic surgery (MMS). Methods We enrolled 100 patients with invasive SCC or BCC. Prior to the first stage of MMS, a Mohs surgeon delineated the intended surgical margin. Subsequently, a trained ultrasound technologist independently evaluated disease extent using the EPISCAN I-200 to evaluate tumor extent beyond this margin. The accuracy of HIFU was subsequently tested by comparison to pathology from frozen sections. Results The test characteristics of the ultrasound were sensitivity= 32%, specificity= 88%, positive predictive value= 47%, and negative predictive value=79%. Subgroup analyses demonstrated improved test characteristics for tumors larger than the median (area >1.74 cm2). Qualitative analyses showed that HIFU was less likely to identify extension from tumors with subtle areas of extension, such as small foci of dermal invasion from infiltrative SCC and micronodular BCC. Conclusions HIFU requires additional refinements to improve the preoperative determination of tumor extent prior to surgical treatment of NMSC. PMID:19018815

On the assessment of marginal life saving costs for risk acceptance criteria

DEFF Research Database (Denmark)

Fischer, Katharina; Virguez, Edgar; Sánchez-Silva, Mauricio

2013-01-01

: The definition of the marginal life saving costs, the discount rate used for comparing costs and benefits that accrue at different points in time and the time horizon over which future consequences of the decision are taken into account. In the present paper these issues are discussed based on a clear...

Informing practice regarding marginalization: the application of the Koci Marginality Index.

Science.gov (United States)

Koci, Anne Floyd; McFarlane, Judith; Nava, Angeles; Gilroy, Heidi; Maddoux, John

2012-12-01

The 49th World Health Assembly of the World Health Organization (WHO) declared violence as the leading worldwide public health problem with a focus on the increase in the incidence of injuries to women. Violence against women is an international epidemic with specific instruments required to measure the impact on women's functioning. This article describes the application of the Koci Marginality Index (KMI), a 5-item scale to measure marginality, to the baseline data of a seven-year prospective study of 300 abused women: 150 first time users of a shelter and 150 first time applicants for a protection order from the justice system. Validity and reliability of the Koci Marginality Index and its usefulness for best clinical practice and for policy decisions for abused women's health are discussed. The 49th World Health Assembly of the World Health Organization (WHO) declared violence as the leading worldwide public health problem and focused on the increase in the incidence of injuries to women (Krug et al., 2002 ). Violence against women in the form of intimate partner violence (IPV) is costly in terms of dollars and health. In the United States in 2003, estimated costs of IPV approached $8.3 billion (Centers for Disease Control and Prevention [CDC], 2011). Outcomes related to severity of IPV vary but in 2003 victims suffering severe IPV lost nearly 8 million days of paid work, and greater than 5 million days of household productivity annually (CDC, 2011). Besides the evident financial cost of IPV, research confirms that exposure to IPV impacts a woman's health immediately and in the long-term (Breiding, Black, & Ryan, 2008 ; Campbell, 2002 ; CDC, 2011). Such sequela adversely affect the health of women and may increase their marginalization, a concept akin to isolation that may further increase negative effects on health outcomes. Immigrant women are at high risk for IPV (Erez, 2002 ) and those without documentation are at higher risk for marginalization (Montalvo

Whipple Resection: Concordance Between Frozen Section And Permanent Section Diagnosis Of Surgical Margins.

Science.gov (United States)

Bilal, Muhammad; Tariq, Hina; Mamoon, Nadira

2018-01-01

Margin assessment is done in Whipple procedures which are usually performed to resect tumours of head of pancreas and ampullary/periampullary region. Aims and objective of the study are to determine the concordance between frozen sections (FS) and permanent sections (PS) of surgical margins in Whipple resections. It is a retrospective study, from January 2008 to January 2015 (07 years). It includes the specimen with malignancy in final report and for which FS of pancreatic and/or CBD margin(s) were requested. Data was retrieved from Laboratory information system (LIS) database. Of the 41 bile duct margins in cases of ampullary tumours, 03 were positive on FS as well as PS, 35 were negative on FS as well as on PS. Results showed 100% sensitivity, 92.1% specificity, 50% PPV and 100% NPV. Results of 36 pancreatic margins in cases of ampullary showed 100% sensitivity, 97.1% specificity, 50% PPV and 100% NPV. In pancreatic carcinoma cases, none of CBD margins were reported as positive on FS, 02 margins reported as negative were found positive on PS, while 17 were negative on FS as well as PS. Results showed 100% specificity and 89.5% NPV. Of the 27 pancreatic margins tested in pancreatic tumours 100% sensitivity, 94.1% specificity, 88.9% PPV and 100% NPV was found. Factors such as absent prior tissue diagnosis and/or inflammatory processes make margin diagnosis difficult. However, a high concordance was observed between our FS and PS diagnosis.

Head and Neck Margin Reduction With Adaptive Radiation Therapy: Robustness of Treatment Plans Against Anatomy Changes

International Nuclear Information System (INIS)

Kranen, Simon van; Hamming-Vrieze, Olga; Wolf, Annelisa; Damen, Eugène; Herk, Marcel van; Sonke, Jan-Jakob

2016-01-01

Purpose: We set out to investigate loss of target coverage from anatomy changes in head and neck cancer patients as a function of applied safety margins and to verify a cone beam computed tomography (CBCT)–based adaptive strategy with an average patient anatomy to overcome possible target underdosage. Methods and Materials: For 19 oropharyngeal cancer patients, volumetric modulated arc therapy treatment plans (2 arcs; simultaneous integrated boost, 70 and 54.25 Gy; 35 fractions) were automatically optimized with uniform clinical target volume (CTV)–to–planning target volume margins of 5, 3, and 0 mm. We applied b-spline CBCT–to–computed tomography (CT) deformable registration to allow recalculation of the dose on modified CT scans (planning CT deformed to daily CBCT following online positioning) and dose accumulation in the planning CT scan. Patients with deviations in primary or elective CTV coverage >2 Gy were identified as candidates for adaptive replanning. For these patients, a single adaptive intervention was simulated with an average anatomy from the first 10 fractions. Results: Margin reduction from 5 mm to 3 mm to 0 mm generally led to an organ-at-risk (OAR) mean dose (D_m_e_a_n) sparing of approximately 1 Gy/mm. CTV shrinkage was mainly seen in the elective volumes (up to 10%), likely related to weight loss. Despite online repositioning, substantial systematic errors were present (>3 mm) in lymph node CTV, the parotid glands, and the larynx. Nevertheless, the average increase in OAR dose was small: maximum of 1.2 Gy (parotid glands, D_m_e_a_n) for all applied margins. Loss of CTV coverage >2 Gy was found in 1, 3, and 7 of 73 CTVs, respectively. Adaptive intervention in 0-mm plans substantially improved coverage: in 5 of 7 CTVs (in 6 patients) to 2 Gy in 0-mm plans may be identified early in treatment using dose accumulation. A single intervention with an average anatomy derived from CBCT effectively mitigates discrepancies.

Seismic margin reviews of nuclear power plants: Identification of important functions and systems

International Nuclear Information System (INIS)

Prassinos, P.G.; Moore, D.L.; Amico, P.J.

1987-01-01

The results from the review of the seven utility-sponsored seismic PRAs plus the Zion SSMRP have been used to develop some insights regarding the importance of various systems and functions to seismic margins. By taking this information and combining it with the fragility insights we can develop some functional/systemic screening guideline for margin studies. This screening approach will greatly reduce the scope of the analysis. It is possible only to come to conclusions regarding the importance of plant systems and safety functions for PWRs, for which six plants were studied. For PWRs, it is possible to categorize plant safety functions as belonging to one of two groups, one of which is important to the assessment of seismic margins and one of which is not. The important functional group involves only two functions that must be considered for estimating seismic margin. These two functions are shutting down the nuclear reaction and providing cooling to the reactor core in the time period immediately following the seismic event (that is, the injection phase or pre-residual heat removal time period). It is possible to reasonably estimate the seismic margin of the plant by performing a study only involving the analysis of the plant systems and structure which are required in order to perform the two functions. Such analysis must include an assessment of a complete set of seismic initiating events. (orig./HP)

Identifying Gaps in the Performance of Pediatric Trainees Who Receive Marginal/Unsatisfactory Ratings.

Science.gov (United States)

Li, Su-Ting T; Tancredi, Daniel J; Schwartz, Alan; Guillot, Ann; Burke, Ann; Trimm, R Franklin; Guralnick, Susan; Mahan, John D; Gifford, Kimberly A

2018-01-01

To perform a derivation study to determine in which subcompetencies marginal/unsatisfactory pediatric residents had the greatest deficits compared with their satisfactorily performing peers and which subcompetencies best discriminated between marginal/unsatisfactory and satisfactorily performing residents. Multi-institutional cohort study of all 21 milestones (rated on four or five levels) reported to the Accreditation Council for Graduate Medical Education, and global marginal/unsatisfactory versus satisfactory performance reported to the American Board of Pediatrics. Data were gathered in 2013-2014. For each level of training (postgraduate year [PGY] 1, 2, and 3), mean differences between milestone levels of residents with marginal/unsatisfactory and satisfactory performance adjusted for clustering by program and C-statistics (area under receiver operating characteristic curve) were calculated. A Bonferroni-corrected significance threshold of .0007963 was used to account for multiple comparisons. Milestone and overall performance evaluations for 1,704 pediatric residents in 41 programs were obtained. For PGY1s, two subcompetencies had almost a one-point difference in milestone levels between marginal/unsatisfactory and satisfactory trainees and outstanding discrimination (≥ 0.90): organize/prioritize (0.93; C-statistic: 0.91) and transfer of care (0.97; C-statistic: 0.90). The largest difference between marginal/unsatisfactory and satisfactory PGY2s was trustworthiness (0.78). The largest differences between marginal/unsatisfactory and satisfactory PGY3s were ethical behavior (1.17), incorporating feedback (1.03), and professionalization (0.96). For PGY2s and PGY3s, no subcompetencies had outstanding discrimination. Marginal/unsatisfactory pediatric residents had different subcompetency gaps at different training levels. While PGY1s may have global deficits, senior residents may have different performance deficiencies requiring individualized counseling and

Bridging greenhouse gas emissions and renewable energy deployment target: Comparative assessment of China and India

International Nuclear Information System (INIS)

Mittal, Shivika; Dai, Hancheng; Fujimori, Shinichiro; Masui, Toshihiko

2016-01-01

Highlights: • India and China’s latest renewable energy targets toward 2030 are assessed. • Carbon emission cap is in line with 2-degree target and governmental commitment. • The impacts of renewable energy on emissions and mitigation costs are quantified. - Abstract: Renewable energy has a critical role in limiting the greenhouse gas (GHG) emissions. This paper assesses the implication of aligning renewable energy deployment target with national emission reduction target for mitigation cost. The assessment methodology uses Asia-Pacific Integrated Assessment/computable general equilibrium (AIM/CGE) model to determine the mitigation cost in terms of GDP and welfare loss under alternative renewable targets in different climate-constrained scenarios. A range of country-specific emission constraints is taken to address the uncertainties related to global emission pathway and emission entitlement scheme. Comparative results show that China needs to increase its share of non-fossil fuel significantly in the primary energy mix to achieve the stringent emission reduction target compared to India. The mitigation cost in terms of economic and welfare loss can be reduced by increasing the penetration of the renewable energy to achieve the same emission reduction target. The modeling results show that coordinated national climate and renewable energy policies help to achieve the GHG emission reduction target in an efficient and cost-effective manner.

Label-free reflectance hyperspectral imaging for tumor margin assessment: a pilot study on surgical specimens of cancer patients

Science.gov (United States)

Fei, Baowei; Lu, Guolan; Wang, Xu; Zhang, Hongzheng; Little, James V.; Patel, Mihir R.; Griffith, Christopher C.; El-Diery, Mark W.; Chen, Amy Y.

2017-08-01

A label-free, hyperspectral imaging (HSI) approach has been proposed for tumor margin assessment. HSI data, i.e., hypercube (x,y,λ), consist of a series of high-resolution images of the same field of view that are acquired at different wavelengths. Every pixel on an HSI image has an optical spectrum. In this pilot clinical study, a pipeline of a machine-learning-based quantification method for HSI data was implemented and evaluated in patient specimens. Spectral features from HSI data were used for the classification of cancer and normal tissue. Surgical tissue specimens were collected from 16 human patients who underwent head and neck (H&N) cancer surgery. HSI, autofluorescence images, and fluorescence images with 2-deoxy-2-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]-D-glucose (2-NBDG) and proflavine were acquired from each specimen. Digitized histologic slides were examined by an H&N pathologist. The HSI and classification method were able to distinguish between cancer and normal tissue from the oral cavity with an average accuracy of 90%±8%, sensitivity of 89%±9%, and specificity of 91%±6%. For tissue specimens from the thyroid, the method achieved an average accuracy of 94%±6%, sensitivity of 94%±6%, and specificity of 95%±6%. HSI outperformed autofluorescence imaging or fluorescence imaging with vital dye (2-NBDG or proflavine). This study demonstrated the feasibility of label-free, HSI for tumor margin assessment in surgical tissue specimens of H&N cancer patients. Further development of the HSI technology is warranted for its application in image-guided surgery.

Evaluation of marginal fit of two all-ceramic copings with two finish lines

Science.gov (United States)

Subasi, Gulce; Ozturk, Nilgun; Inan, Ozgur; Bozogullari, Nalan

2012-01-01

Objectives: This in-vitro study investigated the marginal fit of two all-ceramic copings with 2 finish line designs. Methods: Forty machined stainless steel molar die models with two different margin designs (chamfer and rounded shoulder) were prepared. A total of 40 standardized copings were fabricated and divided into 4 groups (n=10 for each finish line-coping material). Coping materials tested were IPS e.max Press and Zirkonzahn; luting agent was Variolink II. Marginal fit was evaluated after cementation with a stereomicroscope (Leica MZ16). Two-way analysis of variance and Tukey-HSD test were performed to assess the influence of each finish line design and ceramic type on the marginal fit of 2 all-ceramic copings (α =.05). Results: Two-way analysis of variance revealed no statistically significant differences for marginal fit relative to finish lines (P=.362) and ceramic types (P=.065). Conclusion: Within the limitations of this study, both types of all-ceramic copings demonstrated that the mean marginal fit was considered acceptable for clinical application (⩽120 μm). PMID:22509119

Repeat CT assessed CTV variation and PTV margins for short- and long-course pre-operative RT of rectal cancer

International Nuclear Information System (INIS)

Nijkamp, Jasper; Swellengrebel, Maurits; Hollmann, Birgit; Jong, Rianne de; Marijnen, Corrie; Vliet-Vroegindeweij, Corine van; Triest, Baukelien van; Herk, Marcel van; Sonke, Jan-Jakob

2012-01-01

Purpose: To quantify the inter-fraction shape variation of the CTV in rectal-cancer patients treated with 5 × 5 (SCRT) and 25 × 2 Gy (LCRT) and derive PTV margins. Methods and materials: Thirty-three SCRT with daily repeat CT scans and 30 LCRT patients with daily scans during the first week followed by weekly scans were included. The CTV was delineated on all scans and local shape variation was calculated with respect to the planning CT. Margin estimation was done using the local shape variation to assure 95% minimum dose for at least 90% of patients. Results: Using 482 CT scans, systematic and random CTV shape variation was heterogeneous, ranging from 0.2 cm close to bony structures up to 1.0 cm SD at the upper-anterior CTV region. A significant reduction in rectal volume during LCRT resulted in an average 0.5 cm posterior shift of the upper-anterior CTV. Required margins ranged from 0.7 cm close to bony structures up to 3.1 and 2.3 cm in the upper-anterior region for SCRT and LCRT, respectively. Conclusions: Heterogeneous shape variation demands anisotropic PTV margins. Required margins were substantially larger in the anterior direction compared to current clinical margins. These larger margins were, however, based on strict delineated CTVs, resulting in smaller PTVs compared to current practice.

Robustness studies of ignition targets for the National Ignition Facility in two dimensions

International Nuclear Information System (INIS)

Clark, Daniel S.; Haan, Steven W.; Salmonson, Jay D.

2008-01-01

Inertial confinement fusion capsules are critically dependent on the integrity of their hot spots to ignite. At the time of ignition, only a certain fractional perturbation of the nominally spherical hot spot boundary can be tolerated and the capsule still achieve ignition. The degree to which the expected hot spot perturbation in any given capsule design is less than this maximum tolerable perturbation is a measure of the ignition margin or robustness of that design. Moreover, since there will inevitably be uncertainties in the initial character and implosion dynamics of any given capsule, all of which can contribute to the eventual hot spot perturbation, quantifying the robustness of that capsule against a range of parameter variations is an important consideration in the capsule design. Here, the robustness of the 300 eV indirect drive target design for the National Ignition Facility [Lindl et al., Phys. Plasmas 11, 339 (2004)] is studied in the parameter space of inner ice roughness, implosion velocity, and capsule scale. A suite of 2000 two-dimensional simulations, run with the radiation hydrodynamics code LASNEX, is used as the data base for the study. For each scale, an ignition region in the two remaining variables is identified and the ignition cliff is mapped. In accordance with the theoretical arguments of Levedahl and Lindl [Nucl. Fusion 37, 165 (1997)] and Kishony and Shvarts [Phys. Plasmas 8, 4925 (2001)], the location of this cliff is fitted to a power law of the capsule implosion velocity and scale. It is found that the cliff can be quite well represented in this power law form, and, using this scaling law, an assessment of the overall (one- and two-dimensional) ignition margin of the design can be made. The effect on the ignition margin of an increase or decrease in the density of the target fill gas is also assessed

Interfractional Target Variations for Partial Breast Irradiation

International Nuclear Information System (INIS)

Ahunbay, Ergun E.; Robbins, Jared; Christian, Robert; Godley, Andrew; White, Julia; Li, X. Allen

2012-01-01

Purpose: In this work, we quantify the interfractional variations in the shape of the clinical target volume (CTV) by analyzing the daily CT data acquired during CT-guided partial breast irradiation (PBI) and compare the effectiveness of various repositioning alignment strategies considered to account for the variations. Methods and Materials: The daily CT data for 13 breast cancer patients treated with PBI in either prone (10 patients) or supine (3 patients) with daily kV CT guidance using CT on Rails (CTVision, Siemens, Malvern, PA) were analyzed. For approximately 25 points on the surface of the CTV, deformation vectors were calculated by means of deformable image registration and verified by visual inspection. These were used to calculate the distances along surface normals (DSN), which directly related to the required margin expansions for each point. The DSN values were determined for seven alignment methods based on volumetric imaging and also two-dimensional projections (portal imaging). Results: The margin expansion necessary to cover 99% of all points for all days was 2.7 mm when utilizing the alignment method based on deformation field data (the best alignment method). The center-of-mass based alignment yielded slightly worse results (a margin of 4.0 mm), and shifts obtained by operator placement (7.9 mm), two-dimensional-based methods (7.0–10.1 mm), and skin marks (13.9 mm) required even larger margin expansions. Target shrinkage was evident for most days by the negative values of DSN. Even with the best alignment, the range of DSN values could be as high as 7 mm, resulting in a large amount of normal tissue irradiation, unless adaptive replanning is employed. Conclusion: The appropriate alignment method is important to minimize the margin requirement to cover the significant interfractional target deformations observed during PBI. The amount of normal tissue unnecessarily irradiated is still not insignificant, and can be minimized if adaptive

Marginal Abatement Cost of CO2 in China Based on Directional Distance Function: An Industry Perspective

Directory of Open Access Journals (Sweden)

Bowen Xiao

2017-01-01

Full Text Available Industrial sectors account for around 70% of the total energy-related CO2 emissions in China. It is of great importance to measure the potential for CO2 emissions reduction and calculate the carbon price in industrial sectors covered in the Emissions Trading Scheme and carbon tax. This paper employs the directional distance function to calculate the marginal abatement costs of CO2 emissions during 2005–2011 and makes a comparative analysis between our study and the relevant literature. Our empirical results show that the marginal abatement costs vary greatly from industry to industry: high marginal abatement costs occur in industries with low carbon intensity, and vice versa. In the application of the marginal abatement cost, the abatement distribution scheme with minimum cost is established under different abatement targets. The conclusions of abatement distribution scheme indicate that those heavy industries with low MACs and high carbon intensity should take more responsibility for emissions reduction and vice versa. Finally, the policy implications for marginal abatement cost are provided.

ASSESSMENT OF THE TSUNAMIGENIC POTENTIAL ALONG THE NORTHERN CARIBBEAN MARGIN Case Study: Earthquake and Tsunamis of 12 January 2010 in Haiti.

Directory of Open Access Journals (Sweden)

George Pararas-Carayannis

2010-01-01

Full Text Available The potential tsunami risk for Hispaniola, as well as for the other Greater Antilles Islands is assessed by reviewing the complex geotectonic processes and regimes along the Northern Caribbean margin, including the convergent, compressional and collisional tectonic activity of subduction, transition, shearing, lateral movements, accretion and crustal deformation caused by the eastward movement of the Caribbean plate in relation to the North American plate. These complex tectonic interactions have created a broad, diffuse tectonic boundary that has resulted in an extensive, internal deformational sliver slab - the Gonâve microplate – as well as further segmentation into two other microplates with similarly diffused boundary characteristics where tsunamigenic earthquakes have and will again occur. The Gonâve microplate is the most prominent along the Northern Caribbean margin and extends from the Cayman Spreading Center to Mona Pass, between Puerto Rico and the island of Hispaniola, where the 1918 destructive tsunami was generated. The northern boundary of this sliver microplate is defined by the Oriente strike-slip fault south of Cuba, which appears to be an extension of the fault system traversing the northern part of Hispaniola, while the southern boundary is defined by another major strike-slip fault zone where the Haiti earthquake of 12 January 2010 occurred. Potentially tsunamigenic regions along the Northern Caribbean margin are located not only along the boundaries of the Gonâve microplate’s dominant western transform zone but particularly within the eastern tectonic regimes of the margin where subduction is dominant - particularly along the Puerto Rico trench. The Haiti earthquake of 12 January 2010 and its focal mechanism are examined, as they provide additional clues of potential tsunami generation that can occur along transform zones and, more specifically, from interplate and intraplate seismic events and subsequently induced

Tumor Localization Using Cone-Beam CT Reduces Setup Margins in Conventionally Fractionated Radiotherapy for Lung Tumors

International Nuclear Information System (INIS)

Yeung, Anamaria R.; Li, Jonathan G.; Shi Wenyin; Newlin, Heather E.; Chvetsov, Alexei; Liu, Chihray; Palta, Jatinder R.; Olivier, Kenneth

2009-01-01

Purpose: To determine whether setup margins can be reduced using cone-beam computed tomography (CBCT) to localize tumor in conventionally fractionated radiotherapy for lung tumors. Methods and Materials: A total of 22 lung cancer patients were treated with curative intent with conventionally fractionated radiotherapy using daily image guidance with CBCT. Of these, 13 lung cancer patients had sufficient CBCT scans for analysis (389 CBCT scans). The patients underwent treatment simulation in the BodyFix immobilization system using four-dimensional CT to account for respiratory motion. Daily alignment was first done according to skin tattoos, followed by CBCT. All 389 CBCT scans were retrospectively registered to the planning CT scans using automated soft-tissue and bony registration; the resulting couch shifts in three dimensions were recorded. Results: The daily alignment to skin tattoos with no image guidance resulted in systematic (Σ) and random (σ) errors of 3.2-5.6 mm and 2.0-3.5 mm, respectively. The margin required to account for the setup error introduced by aligning to skin tattoos with no image guidance was approximately 1-1.6 cm. The difference in the couch shifts obtained from the bone and soft-tissue registration resulted in systematic (Σ) and random (σ) errors of 1.5-4.1 mm and 1.8-5.3 mm, respectively. The margin required to account for the setup error introduced using bony anatomy as a surrogate for the target, instead of localizing the target itself, was 0.5-1.4 cm. Conclusion: Using daily CBCT soft-tissue registration to localize the tumor in conventionally fractionated radiotherapy reduced the required setup margin by up to approximately 1.5 cm compared with both no image guidance and image guidance using bony anatomy as a surrogate for the target.

Ion tail filling in laser-fusion targets

International Nuclear Information System (INIS)

Henderson, D.B.

1975-06-01

Thermonuclear burn begins in laser-fusion targets with the collapse of the imploding fuel shell. At this instant the ion velocity distribution is non-Maxwellian, requiring correction to the commonly used computer simulation codes. This correction is computed and compared with that arising from the loss of fast ions in marginal (rho R less than 0.01 gm cm -2 ) targets. (U.S.)

A method of accurate determination of voltage stability margin

Energy Technology Data Exchange (ETDEWEB)

Wiszniewski, A.; Rebizant, W. [Wroclaw Univ. of Technology, Wroclaw (Poland); Klimek, A. [AREVA Transmission and Distribution, Stafford (United Kingdom)

2008-07-01

In the process of developing power system disturbance, voltage instability at the receiving substations often contributes to deteriorating system stability, which eventually may lead to severe blackouts. The voltage stability margin at receiving substations may be used to determine measures to prevent voltage collapse, primarily by operating or blocking the transformer tap changing device, or by load shedding. The best measure of the stability margin is the actual load to source impedance ratio and its critical value, which is unity. This paper presented an accurate method of calculating the load to source impedance ratio, derived from the Thevenin's equivalent circuit of the system, which led to calculation of the stability margin. The paper described the calculation of the load to source impedance ratio including the supporting equations. The calculation was based on the very definition of voltage stability, which says that system stability is maintained as long as the change of power, which follows the increase of admittance is positive. The testing of the stability margin assessment method was performed in a simulative way for a number of power network structures and simulation scenarios. Results of the simulations revealed that this method is accurate and stable for all possible events occurring downstream of the device location. 3 refs., 8 figs.

Lateral view dissection of the prostato-urethral junction to reduce positive apical margin in laparoscopic radical prostatectomy.

Science.gov (United States)

Sasaki, Hiroshi; Miki, Jun; Kimura, Takahiro; Sanuki, Kunitaro; Miki, Kenta; Takahashi, Hiroyuki; Egawa, Shin

2009-08-01

To assess the impact of lateral view apical dissection in laparoscopic radical prostatectomy (LRP) on the reduction of positive surgical margin rates and recovery of postoperative continence. One hundred and forty-four consecutive patients underwent LRP from October 2004 to March 2008. Lateral view dissection of the prostato-urethral junction was conducted in 76 of them (Group 2). Standard dissection was used in the remaining patients (Group 1). The effect of this technical modification on the reduction of positive surgical margin rates and postoperative recovery of urinary continence was assessed in the two groups. Overall, the incidence of positive margins decreased from 23 (35.9%) in Group 1 to 16 cases (21.9%) in Group 2 (P = 0.07). Positive margin rates in pT2 decreased from 30.6% to 6.5% (P = 0.006). Apical and dorso-apical margins were reduced from 26.5% to 4.3% (P = 0.009) and from 10.2% to 0% (P Lateral view dissection of the prostato-urethral junction is an easily applicable technical modification. It provides better visualization of apical anatomy substantially contributing to the reduction of positive surgical margin rates, especially at the level of prostatic apex.

Assessment of deoxyhypusine hydroxylase as a putative, novel drug target.

Science.gov (United States)

Kerscher, B; Nzukou, E; Kaiser, A

2010-02-01

Antimalarial drug resistance has nowadays reached each drug class on the market for longer than 10 years. The focus on validated, classical targets has severe drawbacks. If resistance is arising or already present in the field, a target-based High-Throughput-Screening (HTS) with the respective target involves the risk of identifying compounds to which field populations are also resistant. Thus, it appears that a rewarding albeit demanding challenge for target-based drug discovery is to identify novel drug targets. In the search for new targets for antimalarials, we have investigated the biosynthesis of hypusine, present in eukaryotic initiation factor 5A (eIF5A). Deoxyhypusine hydroxylase (DOHH), which has recently been cloned and expressed from P. falciparum, completes the modification of eIF5A through hydroxylation. Here, we assess the present druggable data on Plasmodium DOHH and its human counterpart. Plasmodium DOHH arose from a cyanobacterial phycobilin lyase by loss of function. It has a low FASTA score of 27 to its human counterpart. The HEAT-like repeats present in the parasite DOHH differ in number and amino acid identity from its human ortholog and might be of considerable interest for inhibitor design.

The Provision of Services, Interest Margins and Loan Pricing in European Banking

OpenAIRE

Lepetit , Laetitia; Nys , Emmanuelle; Rous , Philippe; Tarazi , Amine

2006-01-01

This paper assesses the implications on bank interest margins of the expansion into non- traditional fee-based activities in European banking. We use a sample of 602 European commercial and cooperative banks from 1996 to 2002 and consider the total income shares of trading income and commission and fee income as measures of product diversification to explore loan pricing. Our results show that a higher income share from commission and fee activities is associated with lower margins and lower ...

Margin improvement initiatives: realistic approaches

Energy Technology Data Exchange (ETDEWEB)

Chan, P.K.; Paquette, S. [Royal Military College of Canada, Chemistry and Chemical Engineering Dept., Kingston, ON (Canada); Cunning, T.A. [Department of National Defence, Ottawa, ON (Canada); French, C.; Bonin, H.W. [Royal Military College of Canada, Chemistry and Chemical Engineering Dept., Kingston, ON (Canada); Pandey, M. [Univ. of Waterloo, Waterloo, ON (Canada); Murchie, M. [Cameco Fuel Manufacturing, Port Hope, ON (Canada)

2014-07-01

With reactor core aging, safety margins are particularly tight. Two realistic and practical approaches are proposed here to recover margins. The first project is related to the use of a small amount of neutron absorbers in CANDU Natural Uranium (NU) fuel bundles. Preliminary results indicate that the fuelling transient and subsequent reactivity peak can be lowered to improve the reactor's operating margins, with minimal impact on burnup when less than 1000 mg of absorbers is added to a fuel bundle. The second project involves the statistical analysis of fuel manufacturing data to demonstrate safety margins. Probability distributions are fitted to actual fuel manufacturing datasets provided by Cameco Fuel Manufacturing, Inc. They are used to generate input for ELESTRES and ELOCA. It is found that the fuel response distributions are far below industrial failure limits, implying that margin exists in the current fuel design. (author)

Precessional control of Sr ratios in marginal basins during the Messinian Salinity Crisis?

Science.gov (United States)

Topper, R. P. M.; Lugli, S.; Manzi, V.; Roveri, M.; Meijer, P. Th.

2014-05-01

Based on 87Sr/86Sr data of the Primary Lower Gypsum (PLG) deposits in the Vena del Gesso basin—a marginal basin of the Mediterranean during the Messinian Salinity Crisis—a correlation between 87Sr/86Sr values and precessional forcing has recently been proposed but not yet confirmed. In this study, a box model is set up to represent the Miocene Mediterranean deep basin and a connected marginal basin. Measurements of 87Sr/86Sr in the Vena del Gesso and estimated salinity extrema are used to constrain model results. In an extensive analysis with this model, we assess whether coeval 87Sr/86Sr and salinity fluctuations could have been forced by precession-driven changes in the fresh water budget. A comprehensive set of the controlling parameters is examined to assess the conditions under which precession-driven 87Sr/86Sr variations occur and to determine the most likely setting for PLG formation. Model results show that precession-driven 87Sr/86Sr and salinity fluctuations in marginal basins are produced in settings within a large range of marginal basin sizes, riverine strontium characteristics, amplitudes of precessional fresh water budget variation, and average fresh water budgets of both the marginal and deep basin. PLG deposition most likely occurred when the Atlantic-Mediterranean connection was restricted, and the average fresh water budget in the Mediterranean was significantly less negative than at present day. Considering the large range of settings in which salinities and 87Sr/86Sr fluctuate on a precessional timescale, 87Sr/86Sr variations are expected to be a common feature in PLG deposits in marginal basins of the Mediterranean.

A Prospective Pathologic Study to Define the Clinical Target Volume for Partial Breast Radiation Therapy in Women With Early Breast Cancer

Energy Technology Data Exchange (ETDEWEB)

Nguyen, Brandon T., E-mail: Brandon.Nguyen@act.gov.au [Department of Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Canberra Hospital, Radiation Oncology Department, Garran, ACT (Australia); Deb, Siddhartha [Department of Anatomical Pathology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Victorian Cancer Biobank, Cancer Council of Victoria, Carlton, Victoria (Australia); Fox, Stephen [Department of Anatomical Pathology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Hill, Prudence [Department of Anatomical Pathology, St. Vincent' s Hospital Melbourne, Fitzroy, Victoria (Australia); Collins, Marnie [Centre for Biostatistics and Clinical Trials, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Chua, Boon H. [Department of Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); University of Melbourne, Parkville, Victoria (Australia)

2012-12-01

Purpose: To determine an appropriate clinical target volume for partial breast radiation therapy (PBRT) based on the spatial distribution of residual invasive and in situ carcinoma after wide local excision (WLE) for early breast cancer or ductal carcinoma in situ (DCIS). Methods and Materials: We performed a prospective pathologic study of women potentially eligible for PBRT who had re-excision and/or completion mastectomy after WLE for early breast cancer or DCIS. A pathologic assessment protocol was used to determine the maximum radial extension (MRE) of residual carcinoma from the margin of the initial surgical cavity. Women were stratified by the closest initial radial margin width: negative (>1 mm), close (>0 mm and {<=}1 mm), or involved. Results: The study population was composed of 133 women with a median age of 59 years (range, 27-82 years) and the following stage groups: 0 (13.5%), I (40.6%), II (38.3%), and III (7.5%). The histologic subtypes of the primary tumor were invasive ductal carcinoma (74.4%), invasive lobular carcinoma (12.0%), and DCIS alone (13.5%). Residual carcinoma was present in the re-excision and completion mastectomy specimens in 55.4%, 14.3%, and 7.2% of women with an involved, close, and negative margin, respectively. In the 77 women with a noninvolved radial margin, the MRE of residual disease, if present, was {<=}10 mm in 97.4% (95% confidence interval 91.6-99.5) of cases. Larger MRE measurements were significantly associated with an involved margin (P<.001), tumor size >30 mm (P=.03), premenopausal status (P=.03), and negative progesterone receptor status (P=.05). Conclusions: A clinical target volume margin of 10 mm would encompass microscopic residual disease in >90% of women potentially eligible for PBRT after WLE with noninvolved resection margins.

A Prospective Pathologic Study to Define the Clinical Target Volume for Partial Breast Radiation Therapy in Women With Early Breast Cancer

International Nuclear Information System (INIS)

Nguyen, Brandon T.; Deb, Siddhartha; Fox, Stephen; Hill, Prudence; Collins, Marnie; Chua, Boon H.

2012-01-01

Purpose: To determine an appropriate clinical target volume for partial breast radiation therapy (PBRT) based on the spatial distribution of residual invasive and in situ carcinoma after wide local excision (WLE) for early breast cancer or ductal carcinoma in situ (DCIS). Methods and Materials: We performed a prospective pathologic study of women potentially eligible for PBRT who had re-excision and/or completion mastectomy after WLE for early breast cancer or DCIS. A pathologic assessment protocol was used to determine the maximum radial extension (MRE) of residual carcinoma from the margin of the initial surgical cavity. Women were stratified by the closest initial radial margin width: negative (>1 mm), close (>0 mm and ≤1 mm), or involved. Results: The study population was composed of 133 women with a median age of 59 years (range, 27-82 years) and the following stage groups: 0 (13.5%), I (40.6%), II (38.3%), and III (7.5%). The histologic subtypes of the primary tumor were invasive ductal carcinoma (74.4%), invasive lobular carcinoma (12.0%), and DCIS alone (13.5%). Residual carcinoma was present in the re-excision and completion mastectomy specimens in 55.4%, 14.3%, and 7.2% of women with an involved, close, and negative margin, respectively. In the 77 women with a noninvolved radial margin, the MRE of residual disease, if present, was ≤10 mm in 97.4% (95% confidence interval 91.6-99.5) of cases. Larger MRE measurements were significantly associated with an involved margin (P 30 mm (P=.03), premenopausal status (P=.03), and negative progesterone receptor status (P=.05). Conclusions: A clinical target volume margin of 10 mm would encompass microscopic residual disease in >90% of women potentially eligible for PBRT after WLE with noninvolved resection margins.

The marginal costs of greenhouse gas emissions

International Nuclear Information System (INIS)

Tol, R.S.J.

1999-01-01

Estimates of the marginal costs of greenhouse gas emissions are on important input to the decision how much society would want to spend on greenhouse gas emission reduction. Marginal cost estimates in the literature range between $5 and $25 per ton of carbon. Using similar assumptions, the FUND model finds marginal costs of $9--23/tC, depending on the discount rate. If the aggregation of impacts over countries accounts for inequalities in income distribution or for risk aversion, marginal costs would rise by about a factor of 3. Marginal costs per region are an order of magnitude smaller than global marginal costs. The ratios between the marginal costs of CO 2 and those of CH 4 and N 2 O are roughly equal to the global warming potentials of these gases. The uncertainty about the marginal costs is large and right-skewed. The expected value of the marginal costs lies about 35% above the best guess, the 95-percentile about 250%

PIRATE: pediatric imaging response assessment and targeting environment

Science.gov (United States)

Glenn, Russell; Zhang, Yong; Krasin, Matthew; Hua, Chiaho

2010-02-01

By combining the strengths of various imaging modalities, the multimodality imaging approach has potential to improve tumor staging, delineation of tumor boundaries, chemo-radiotherapy regime design, and treatment response assessment in cancer management. To address the urgent needs for efficient tools to analyze large-scale clinical trial data, we have developed an integrated multimodality, functional and anatomical imaging analysis software package for target definition and therapy response assessment in pediatric radiotherapy (RT) patients. Our software provides quantitative tools for automated image segmentation, region-of-interest (ROI) histogram analysis, spatial volume-of-interest (VOI) analysis, and voxel-wise correlation across modalities. To demonstrate the clinical applicability of this software, histogram analyses were performed on baseline and follow-up 18F-fluorodeoxyglucose (18F-FDG) PET images of nine patients with rhabdomyosarcoma enrolled in an institutional clinical trial at St. Jude Children's Research Hospital. In addition, we combined 18F-FDG PET, dynamic-contrast-enhanced (DCE) MR, and anatomical MR data to visualize the heterogeneity in tumor pathophysiology with the ultimate goal of adaptive targeting of regions with high tumor burden. Our software is able to simultaneously analyze multimodality images across multiple time points, which could greatly speed up the analysis of large-scale clinical trial data and validation of potential imaging biomarkers.

Refining margins: recent trends

International Nuclear Information System (INIS)

Baudoin, C.; Favennec, J.P.

1999-01-01

Despite a business environment that was globally mediocre due primarily to the Asian crisis and to a mild winter in the northern hemisphere, the signs of improvement noted in the refining activity in 1996 were borne out in 1997. But the situation is not yet satisfactory in this sector: the low return on invested capital and the financing of environmental protection expenditure are giving cause for concern. In 1998, the drop in crude oil prices and the concomitant fall in petroleum product prices was ultimately rather favorable to margins. Two elements tended to put a damper on this relative optimism. First of all, margins continue to be extremely volatile and, secondly, the worsening of the economic and financial crisis observed during the summer made for a sharp decline in margins in all geographic regions, especially Asia. Since the beginning of 1999, refining margins are weak and utilization rates of refining capacities have decreased. (authors)

Accountable Accounting: Carbon-Based Management on Marginal Lands

Directory of Open Access Journals (Sweden)

Tara L. DiRocco

2014-04-01

Full Text Available Substantial discussion exists concerning the best land use options for mitigating greenhouse gas (GHG emissions on marginal land. Emissions-mitigating land use options include displacement of fossil fuels via biofuel production and afforestation. Comparing C recovery dynamics under these different options is crucial to assessing the efficacy of offset programs. In this paper, we focus on forest recovery on marginal land, and show that there is substantial inaccuracy and discrepancy in the literature concerning carbon accumulation. We find that uncertainty in carbon accumulation occurs in estimations of carbon stocks and models of carbon dynamics over time. We suggest that analyses to date have been largely unsuccessful at determining reliable trends in site recovery due to broad land use categories, a failure to consider the effect of current and post-restoration management, and problems with meta-analysis. Understanding of C recovery could be greatly improved with increased data collection on pre-restoration site quality, prior land use history, and management practices as well as increased methodological standardization. Finally, given the current and likely future uncertainty in C dynamics, we recommend carbon mitigation potential should not be the only environmental service driving land use decisions on marginal lands.

Identifying cost-minimizing strategies for guaranteeing target dairy income over feed cost via use of the Livestock Gross Margin dairy insurance program.

Science.gov (United States)

Valvekar, M; Cabrera, V E; Gould, B W

2010-07-01

Milk and feed price volatility are the major source of dairy farm risk. Since August 2008 a new federally reinsured insurance program has been available to many US dairy farmers to help minimize the negative effects of adverse price movements. This insurance program is referred to as Livestock Gross Margin Insurance for Dairy Cattle. Given the flexibility in contract design, the dairy farmer has to make 3 critical decisions when purchasing this insurance: 1) the percentage of monthly milk production to be covered, 3) declared feed equivalents used to produce this milk, and 3) the level of gross margin not covered by insurance (i.e., deductible). The objective of this analysis was to provide an optimal strategy of how a dairy farmer could incorporate this insurance program to help manage the variability in net farm income. In this analysis we assumed that a risk-neutral dairy farmer wants to design an insurance contract such that a target guaranteed income over feed cost is obtained at least cost. We undertook this analysis for a representative Wisconsin dairy farm (herd size: 120 cows) producing 8,873 kg (19,545 lb) of milk/cow per year. Wisconsin statistical data indicates that dairy farms of similar size must require an income over feed cost of at least $110/Mg ($5/cwt) of milk to be profitable during the coverage period. Therefore, using data for the July 2009 insurance contract to insure $110/Mg of milk, the least cost contract was found to have a premium of $1.22/Mg ($0.055/cwt) of milk produced insuring approximately 52% of the production with variable monthly production covered during the period of September 2009 to June 2010. This premium represented 1.10% of the desired IOFC. We compared the above optimal strategy with an alternative nonoptimal strategy, defined as a contract insuring the same proportion of milk as the optimal (52%) but with a constant amount insured across all contract months. The premium was found to be almost twice the level obtained

Margin Requirements and Equity Option Returns

DEFF Research Database (Denmark)

Hitzemann, Steffen; Hofmann, Michael; Uhrig-Homburg, Marliese

In equity option markets, traders face margin requirements both for the options themselves and for hedging-related positions in the underlying stock market. We show that these requirements carry a significant margin premium in the cross-section of equity option returns. The sign of the margin...... premium depends on demand pressure: If end-users are on the long side of the market, option returns decrease with margins, while they increase otherwise. Our results are statistically and economically significant and robust to different margin specifications and various control variables. We explain our...... findings by a model of funding-constrained derivatives dealers that require compensation for satisfying end-users’ option demand....

Margin Requirements and Equity Option Returns

DEFF Research Database (Denmark)

Hitzemann, Steffen; Hofmann, Michael; Uhrig-Homburg, Marliese

In equity option markets, traders face margin requirements both for the options themselves and for hedging-related positions in the underlying stock market. We show that these requirements carry a significant "margin premium" in the cross-section of equity option returns. The sign of the margin...... premium depends on demand pressure: If end-users are on the long side of the market, option returns decrease with margins, while they increase otherwise. Our results are statistically and economically significant and robust to different margin specifications and various control variables. We explain our...... findings by a model of funding-constrained derivatives dealers that require compensation for satisfying end-users’ option demand....

Decoding the Margins: What Can the Fractal Geometry of Basaltic Flow Margins Tell Us?

Science.gov (United States)

Schaefer, E. I.; Hamilton, C.; Neish, C.; Beard, S. P.; Bramson, A. M.; Sori, M.; Rader, E. L.

2016-12-01

Studying lava flows on other planetary bodies is essential to characterizing eruption styles and constraining the bodies' thermal evolution. Although planetary basaltic flows are common, many key features are not resolvable in orbital imagery. We are thus developing a technique to characterize basaltic flow type, sub-meter roughness, and sediment mantling from these data. We will present the results from upcoming fieldwork at Craters of the Moon National Monument and Preserve with FINESSE (August) and at Hawai'i Volcanoes National Park (September). We build on earlier work that showed that basaltic flow margins are approximately fractal [Bruno et al., 1992; Gaonac'h et al., 1992] and that their fractal dimensions (D) have distinct `a`ā and pāhoehoe ranges under simple conditions [Bruno et al., 1994]. Using a differential GPS rover, we have recently shown that the margin of Iceland's 2014 Holuhraun flow exhibits near-perfect (R2=0.9998) fractality for ≥24 km across dm to km scales [Schaefer et al., 2016]. This finding suggests that a fractal-based technique has significant potential to characterize flows at sub-resolution scales. We are simultaneously seeking to understand how margin fractality can be modified. A preliminary result for an `a'ā flow in Hawaii's Ka'ū Desert suggests that although aeolian mantling obscures the original flow margin, the apparent margin (i.e., sediment-lava interface) remains fractal [Schaefer et al., 2015]. Further, the apparent margin's D is likely significantly modified from that of the original margin. Other factors that we are exploring include erosion, transitional flow types, and topographic confinement. We will also rigorously test the intriguing possibility that margin D correlates with the sub-meter Hurst exponent H of the flow surface, a common metric of roughness scaling [e.g., Shepard et al., 2001]. This hypothesis is based on geometric arguments [Turcotte, 1997] and is qualitatively consistent with all results so far.

Oral antioxidant therapy for marginal dry eye.

Science.gov (United States)

Blades, K J; Patel, S; Aidoo, K E

2001-07-01

To assess the efficacy of an orally administered antioxidant dietary supplement for managing marginal dry eye. A prospective, randomised, placebo controlled trial with cross-over. Eye Clinic, Department of Vision Sciences, Glasgow Caledonian University. Forty marginal dry eye sufferers composed of 30 females and 10 males (median age 53 y; range 38-69 y). Baseline assessments were made of tear volume sufficiency (thread test), tear quality (stability), ocular surface status (conjunctival impression cytology) and dry eye symptoms (questionnaire). Each subject was administered courses of active treatment, placebo and no treatment, in random order for 1 month each and results compared to baseline. Tear stability and ocular surface status were significantly improved following active treatment (Ptreatment (P>0.05). Absolute increase in tear stability correlated with absolute change in goblet cell population density. Tear volume was not improved following any treatment period and dry eye symptom responses were subject to placebo effect. Oral antioxidants improved both tear stability and conjunctival health, although it is not yet understood whether increased ocular surface health mediates increased tear stability or vice versa. This study was supported by a PhD scholarship funded by the Department of Vision Sciences, Glasgow Caledonian University, Scotland. Antioxidant supplements and placebos were kindly donated by Vitabiotics.

Assessment of a Targeted Trap-Neuter-Return Pilot Study in Auckland, New Zealand.

Science.gov (United States)

Zito, Sarah; Aguilar, Glenn; Vigeant, Shalsee; Dale, Arnja

2018-05-13

There is a need for effective and humane management tools to manage urban stray cats and minimise negative impacts associated with stray cats. One such tool is targeted trap-neuter-return (TTNR), but no concerted implementation of this technique or formal assessments have been reported. To address this deficit, a TTNR programme was implemented and assessed in one Auckland suburb from May 2015 to June 2016; the programme sterilised and returned 348 cats (4.2 cats/1000 residents). Assessment was based on the number of incoming felines; stray, unsocialised cats euthanased; unsocialised, unowned cats sterilised and returned (independently of the TTNR programme); and neonatal/underage euthanasias. Incoming stray felines, underage euthanasias, and unsocialised stray cat euthanasias were all reduced for the targeted suburb when compared for the years before and after the programme (the percentage reduction in these parameters was −39, −17, −34, −7, and −47, respectively). These outcome measures had a greater reduction in the targeted suburb compared to the Auckland suburbs not targeted by the TTNR programme ( p < 0.01), although causation cannot be inferred, as a variety of reasons could have contributed to the changes. This pilot programme suggests that TTNR could be a valuable, humane cat management tool in urban New Zealand, and further assessment is warranted.

In vitro analysis of the marginal adaptation and discrepancy of stainless steel crowns

Science.gov (United States)

Mulder, Riaan; Medhat, Rasha; Mohamed, Nadia

2018-01-01

Abstract Aim: The purpose of the study was to assess the marginal adaptation and discrepancy of SSC’s. Differences in adaptation and discrepancy between the four surfaces (mesial, lingual, distal, and buccal) were evaluated. Methods: The placement of stainless steel crowns were completed on a phantom head in accordance with the clinical technique. The ideal tooth preparation was made and this ‘master tooth’ duplicated to achieve a sample size of 15. The stainless steel crowns were placed, trimmed, and cemented as per the clinical technique. The cemented stainless crowns were analyzed under 100× stereomicroscope magnification. The marginal adaptation and discrepancy of each specimen was measured every 2 µm. Results: All the specimens showed marginal adaptation and discrepancy. The lingual margin had a significantly better adaptation (p steel crown adaptation and discrepancy is an essential clinical step. PMID:29536024

TU-AB-BRB-00: New Methods to Ensure Target Coverage

International Nuclear Information System (INIS)

2015-01-01

The accepted clinical method to accommodate targeting uncertainties inherent in fractionated external beam radiation therapy is to utilize GTV-to-CTV and CTV-to-PTV margins during the planning process to design a PTV-conformal static dose distribution on the planning image set. Ideally, margins are selected to ensure a high (e.g. >95%) target coverage probability (CP) in spite of inherent inter- and intra-fractional positional variations, tissue motions, and initial contouring uncertainties. Robust optimization techniques, also known as probabilistic treatment planning techniques, explicitly incorporate the dosimetric consequences of targeting uncertainties by including CP evaluation into the planning optimization process along with coverage-based planning objectives. The treatment planner no longer needs to use PTV and/or PRV margins; instead robust optimization utilizes probability distributions of the underlying uncertainties in conjunction with CP-evaluation for the underlying CTVs and OARs to design an optimal treated volume. This symposium will describe CP-evaluation methods as well as various robust planning techniques including use of probability-weighted dose distributions, probability-weighted objective functions, and coverage optimized planning. Methods to compute and display the effect of uncertainties on dose distributions will be presented. The use of robust planning to accommodate inter-fractional setup uncertainties, organ deformation, and contouring uncertainties will be examined as will its use to accommodate intra-fractional organ motion. Clinical examples will be used to inter-compare robust and margin-based planning, highlighting advantages of robust-plans in terms of target and normal tissue coverage. Robust-planning limitations as uncertainties approach zero and as the number of treatment fractions becomes small will be presented, as well as the factors limiting clinical implementation of robust planning. Learning Objectives: To understand

Extensional Fault Evolution and its Flexural Isostatic Response During Iberia-Newfoundland Rifted Margin Formation

Science.gov (United States)

Gómez-Romeu, J.; Kusznir, N.; Manatschal, G.; Roberts, A.

2017-12-01

During the formation of magma-poor rifted margins, upper lithosphere thinning and stretching is achieved by extensional faulting, however, there is still debate and uncertainty how faults evolve during rifting leading to breakup. Seismic data provides an image of the present-day structural and stratigraphic configuration and thus initial fault geometry is unknown. To understand the geometric evolution of extensional faults at rifted margins it is extremely important to also consider the flexural response of the lithosphere produced by fault displacement resulting in footwall uplift and hangingwall subsidence. We investigate how the flexural isostatic response to extensional faulting controls the structural development of rifted margins. To achieve our aim, we use a kinematic forward model (RIFTER) which incorporates the flexural isostatic response to extensional faulting, crustal thinning, lithosphere thermal loads, sedimentation and erosion. Inputs for RIFTER are derived from seismic reflection interpretation and outputs of RIFTER are the prediction of the structural and stratigraphic consequences of recursive sequential faulting and sedimentation. Using RIFTER we model the simultaneous tectonic development of the Iberia-Newfoundland conjugate rifted margins along the ISE01-SCREECH1 and TGS/LG12-SCREECH2 seismic lines. We quantitatively test and calibrate the model against observed target data restored to breakup time. Two quantitative methods are used to obtain this target data: (i) gravity anomaly inversion which predicts Moho depth and continental lithosphere thinning and (ii) reverse post-rift subsidence modelling to give water and Moho depths at breakup time. We show that extensional faulting occurs on steep ( 60°) normal faults in both proximal and distal parts of rifted margins. Extensional faults together with their flexural isostatic response produce not only sub-horizontal exhumed footwall surfaces (i.e. the rolling hinge model) and highly rotated (60�

Engineering measures and risk assessment against fault displacement

International Nuclear Information System (INIS)

Narabayashi, Tadashi; Okamoto, Koji; Dodo, Takashi; Kamiya, Masanobu

2017-01-01

A special committee on 'assessment on fault activities and engineering risk' was established at the Japan Atomic Energy Society. With a participation of the Japan Society of Maintenology, a study group on nuclear safety regulations was established at the Japan Society of Maintenology, and this theme has been examined. Among the technics for evaluating the effects of fault displacement on nuclear facilities, the concept of application of the safety margin evaluation method is shown. By applying this method, it is possible to evaluate nuclear safety against fault displacement, and it is also possible to obtain risk information such as the conditions of facilities and safety functions (retention or loss) as well as the safety margin against core damage, including the event exceeding prediction. Thus, it is possible to verify the effectiveness of accident management and to make decisions for further countermeasures to reduce risk through using the obtained risk information. The countermeasures prepared for large scale damage can also be effectively utilized. It is necessary not only the fault displacement targeted in this paper, but also the results of risk assessment obtained by safety margin assessment etc. are reflected on the improvement of accident management at the site, education and training, and assumption of various events and desk training, and are linked to safety improvement. Efforts for encouraging these actions are also required. (A.O.)

Stock assessment of fishery target species in Lake Koka, Ethiopia

Directory of Open Access Journals (Sweden)

Gashaw Tesfaye

2015-09-01

Full Text Available Effective management is essential for small-scale fisheries to continue providing food and livelihoods for households, particularly in developing countries where other options are often limited. Studies on the population dynamics and stock assessment on fishery target species are thus imperative to sustain their fisheries and the benefits for the society. In Lake Koka (Ethiopia, very little is known about the vital population parameters and exploitation status of the fishery target species: tilapia Oreochromis niloticus,common carp Cyprinus carpióand catfish Clarias gariepinus.Our study, therefore, aimed at determining the vital population parameters and assessing the status of these target species in Lake Koka using length frequency data collected quarterly from commercial catches from 2007-2012. A total of 20 097 fish specimens (distributed as 7 933 tilapia, 6 025 catfish and 6 139 common carp were measured for the analysis. Von Bertalanffy growth parameters and their confidence intervals were determined from modal progression analysis using ELEFAN I and applying the jackknife technique. Mortality parameters were determined from length-converted catch curves and empirical models. The exploitation status of these target species were then assessed by computing exploitation rates (E from mortality parameters as well as from size indicators i.e., assessing the size distribution of fish catches relative to the size at maturity (L m,the size that provides maximum cohort biomass (Lopt and the abundance of mega-spawners. The mean value of growth parameters L x, Kand the growth performance index 0' were 44.5 cm, 0.41/year and 2.90 for O. niloticus,74.1 cm, 0.28/year and 3.19 for C. carpioand 121.9 cm, 0.16/year and 3.36 for C. gariepinus,respectively. The 95 % confidence intervals of the estimates were also computed. Total mortality (Z estimates were 1.47, 0.83 and 0.72/year for O. niloticus, C. carpioand C. gariepinus,respectively. Our study suggest

Probabilistic safety assessment of the Fugen NPS

International Nuclear Information System (INIS)

Sotsu, Masutake; Iguchi, Yukihiro; Mizuno, Kouichi; Sato, Shinichirou; Shimizu, Miwako

1999-01-01

We performed a probabilistic safety assessment (PSA) on the Fugen NPS. The main topic of assessment was internal factors. We assessment core damage frequency (level 1 PSA) and containment damage frequency (level 2 PSA) during rated operation, and core damage frequency during shutdown (PSA during shutdowns). Our assessment showed that the core damage frequency of Fugen is well below the IAEA criteria for existing plants, that the conditional containment damage during shutdown is almost the target value of 0.1, and that the core damage frequency during shutdown is almost the same as that assessed during operation. These results confirm that the Fugen plant maintains a sufficient safety margin during shutdowns for regular inspections and for refueling. We developed and verified the effectiveness of an accident management plan incorporating the results of the assessment. (author)

Splenic marginal zone lymphoma.

Science.gov (United States)

Piris, Miguel A; Onaindía, Arantza; Mollejo, Manuela

Splenic marginal zone lymphoma (SMZL) is an indolent small B-cell lymphoma involving the spleen and bone marrow characterized by a micronodular tumoral infiltration that replaces the preexisting lymphoid follicles and shows marginal zone differentiation as a distinctive finding. SMZL cases are characterized by prominent splenomegaly and bone marrow and peripheral blood infiltration. Cells in peripheral blood show a villous cytology. Bone marrow and peripheral blood characteristic features usually allow a diagnosis of SMZL to be performed. Mutational spectrum of SMZL identifies specific findings, such as 7q loss and NOTCH2 and KLF2 mutations, both genes related with marginal zone differentiation. There is a striking clinical variability in SMZL cases, dependent of the tumoral load and performance status. Specific molecular markers such as 7q loss, p53 loss/mutation, NOTCH2 and KLF2 mutations have been found to be associated with the clinical variability. Distinction from Monoclonal B-cell lymphocytosis with marginal zone phenotype is still an open issue that requires identification of precise and specific thresholds with clinical meaning. Copyright © 2016 Elsevier Ltd. All rights reserved.

Quantitative assessment of inter-observer variability in target volume delineation on stereotactic radiotherapy treatment for pituitary adenoma and meningioma near optic tract

International Nuclear Information System (INIS)

Yamazaki, Hideya; Ogita, Mikio; Yamashita, Koichi; Kotsuma, Tadayuki; Shiomi, Hiroya; Tsubokura, Takuji; Kodani, Naohiro; Nishimura, Takuya; Aibe, Norihiro; Udono, Hiroki; Nishikata, Manabu; Baba, Yoshimi

2011-01-01

To assess inter-observer variability in delineating target volume and organs at risk in benign tumor adjacent to optic tract as a quality assurance exercise. We quantitatively analyzed 21 plans made by 11 clinicians in seven CyberKnife centers. The clinicians were provided with a raw data set (pituitary adenoma and meningioma) including clinical information, and were asked to delineate the lesions and create a treatment plan. Their contouring and plans (10 adenoma and 11 meningioma plans), were then compared. In addition, we estimated the influence of differences in contouring by superimposing the respective contours onto a default plan. The median planning target volume (PTV) and the ratio of the largest to the smallest contoured volume were 9.22 cm 3 (range, 7.17 - 14.3 cm 3 ) and 1.99 for pituitary adenoma, and 6.86 cm 3 (range 6.05 - 14.6 cm 3 ) and 2.41 for meningioma. PTV volume was 10.1 ± 1.74 cm 3 for group 1 with a margin of 1 -2 mm around the CTV (n = 3) and 9.28 ± 1.8 cm 3 (p = 0.51) for group 2 with no margin (n = 7) in pituitary adenoma. In meningioma, group 1 showed larger PTV volume (10.1 ± 3.26 cm 3 ) than group 2 (6.91 ± 0.7 cm 3 , p = 0.03). All submitted plan keep the irradiated dose to optic tract within the range of 50 Gy (equivalent total doses in 2 Gy fractionation). However, contours superimposed onto the dose distribution of the default plan indicated that an excessive dose 23.64 Gy (up to 268% of the default plan) in pituitary adenoma and 24.84 Gy (131% of the default plan) in meningioma to the optic nerve in the contours from different contouring. Quality assurance revealed inter-observer variability in contour delineation and their influences on planning for pituitary adenoma and meningioma near optic tract

Categorical marginal models: quite extensive package for the estimation of marginal models for categorical data

OpenAIRE

Wicher Bergsma; Andries van der Ark

2015-01-01

A package accompanying the book Marginal Models for Dependent, Clustered, and Longitudinal Categorical Data by Bergsma, Croon, & Hagenaars, 2009. It’s purpose is fitting and testing of marginal models.

Characterizing Convexity of Games using Marginal Vectors

NARCIS (Netherlands)

van Velzen, S.; Hamers, H.J.M.; Norde, H.W.

2003-01-01

In this paper we study the relation between convexity of TU games and marginal vectors.We show that if specfic marginal vectors are core elements, then the game is convex.We characterize sets of marginal vectors satisfying this property, and we derive the formula for the minimum number of marginal

Difference in the Set-up Margin between 2D Conventional and 3D CT Based Planning in Patients with Early Breast Cancer

International Nuclear Information System (INIS)

Jo, Sun Mi; Chun, Mi Sun; Kim, Mi Hwa; Oh, Young Taek; Noh, O Kyu; Kang, Seung Hee

2010-01-01

Simulation using computed tomography (CT) is now widely available for radiation treatment planning for breast cancer. It is an important tool to help define the tumor target and normal tissue based on anatomical features of an individual patient. In Korea, most patients have small sized breasts and the purpose of this study was to review the margin of treatment field between conventional two-dimensional (2D) planning and CT based three-dimensional (3D) planning in patients with small breasts. Twenty-five consecutive patients with early breast cancer undergoing breast conservation therapy were selected. All patients underwent 3D CT based planning with a conventional breast tangential field design. In 2D planning, the treatment field margins were determined by palpation of the breast parenchyma (In general, the superior: base of the clavicle, medial: midline, lateral: mid - axillary line, and inferior margin: 2 m below the inflamammary fold). In 3D planning, the clinical target volume (CTV) ought to comprise all glandular breast tissue, and the PTV was obtained by adding a 3D margin of 1 cm around the CTV except in the skin direction. The difference in the treatment field margin and equivalent field size between 2D and 3D planning were evaluated. The association between radiation field margins and factors such as body mass index, menopause status, and bra size was determined. Lung volume and heart volume were examined on the basis of the prescribed breast radiation dose and 3D dose distribution. The margins of the treatment field were smaller in the 3D planning except for two patients. The superior margin was especially variable (average, 2.5 cm; range, -2.5 to 4.5 cm; SD, 1.85). The margin of these targets did not vary equally across BMI class, menopause status, or bra size. The average irradiated lung volume was significantly lower for 3D planning. The average irradiated heart volume did not decrease significantly. The use of 3D CT based planning reduced the

Difference in the Set-up Margin between 2D Conventional and 3D CT Based Planning in Patients with Early Breast Cancer

Energy Technology Data Exchange (ETDEWEB)

Jo, Sun Mi; Chun, Mi Sun; Kim, Mi Hwa; Oh, Young Taek; Noh, O Kyu [Ajou University School of Medicine, Seoul (Korea, Republic of); Kang, Seung Hee [Inje University, Ilsan Paik Hospital, Ilsan (Korea, Republic of)

2010-11-15

Simulation using computed tomography (CT) is now widely available for radiation treatment planning for breast cancer. It is an important tool to help define the tumor target and normal tissue based on anatomical features of an individual patient. In Korea, most patients have small sized breasts and the purpose of this study was to review the margin of treatment field between conventional two-dimensional (2D) planning and CT based three-dimensional (3D) planning in patients with small breasts. Twenty-five consecutive patients with early breast cancer undergoing breast conservation therapy were selected. All patients underwent 3D CT based planning with a conventional breast tangential field design. In 2D planning, the treatment field margins were determined by palpation of the breast parenchyma (In general, the superior: base of the clavicle, medial: midline, lateral: mid - axillary line, and inferior margin: 2 m below the inflamammary fold). In 3D planning, the clinical target volume (CTV) ought to comprise all glandular breast tissue, and the PTV was obtained by adding a 3D margin of 1 cm around the CTV except in the skin direction. The difference in the treatment field margin and equivalent field size between 2D and 3D planning were evaluated. The association between radiation field margins and factors such as body mass index, menopause status, and bra size was determined. Lung volume and heart volume were examined on the basis of the prescribed breast radiation dose and 3D dose distribution. The margins of the treatment field were smaller in the 3D planning except for two patients. The superior margin was especially variable (average, 2.5 cm; range, -2.5 to 4.5 cm; SD, 1.85). The margin of these targets did not vary equally across BMI class, menopause status, or bra size. The average irradiated lung volume was significantly lower for 3D planning. The average irradiated heart volume did not decrease significantly. The use of 3D CT based planning reduced the

12 CFR 220.4 - Margin account.

Science.gov (United States)

2010-01-01

... Banking FEDERAL RESERVE SYSTEM (CONTINUED) BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM CREDIT BY... securities. The required margin on a net long or net short commitment in a when-issued security is the margin...) Interest charged on credit maintained in the margin account; (ii) Premiums on securities borrowed in...

Mean Field Theory, Ginzburg Criterion, and Marginal Dimensionality of Phase-Transitions

DEFF Research Database (Denmark)

Als-Nielsen, Jens Aage; Birgenau, R. J.

1977-01-01

By applying a real space version of the Ginzburg criterion, the role of fluctuations and thence the self‐consistency of mean field theory are assessed in a simple fashion for a variety of phase transitions. It is shown that in using this approach the concept of ’’marginal dimensionality’’ emerges...... in a natural way. For example, it is shown that for many homogeneous structural transformations the marginal dimensionality is two, so that mean field theory will be valid for real three‐dimensional systems. It is suggested that this simple self‐consistent approach to Landau theory should be incorporated...

Conference Report: The New Discovery of Margins: Theory-Based Excursions in Marginal Social Fields

Directory of Open Access Journals (Sweden)

Babette Kirchner

2014-05-01

Full Text Available At this year's spring conference of the Sociology of Knowledge Section of the German Sociological Association, a diverse range of theoretical concepts and multiple empirical insights into different marginal social fields were presented. As in everyday life, drawing a line between center and margin can be seen as an important challenge that must equally be faced in sociology. The socially constructed borderline appears to be highly variable. Therefore it has to be delineated or fixed somehow. The construction of margins is necessary for society in general and smaller social groupings alike to confirm one's own "normal" identity, or one's own membership on the fringes. The different contributions exemplify what was established at the beginning of the conference: Namely that society and its margins are defined differently according to the empirical as well as conceptual focus. URN: http://nbn-resolving.de/urn:nbn:de:0114-fqs1402148

Image-based in vivo assessment of targeting accuracy of stereotactic brain surgery in experimental rodent models

Science.gov (United States)

Rangarajan, Janaki Raman; Vande Velde, Greetje; van Gent, Friso; de Vloo, Philippe; Dresselaers, Tom; Depypere, Maarten; van Kuyck, Kris; Nuttin, Bart; Himmelreich, Uwe; Maes, Frederik

2016-11-01

Stereotactic neurosurgery is used in pre-clinical research of neurological and psychiatric disorders in experimental rat and mouse models to engraft a needle or electrode at a pre-defined location in the brain. However, inaccurate targeting may confound the results of such experiments. In contrast to the clinical practice, inaccurate targeting in rodents remains usually unnoticed until assessed by ex vivo end-point histology. We here propose a workflow for in vivo assessment of stereotactic targeting accuracy in small animal studies based on multi-modal post-operative imaging. The surgical trajectory in each individual animal is reconstructed in 3D from the physical implant imaged in post-operative CT and/or its trace as visible in post-operative MRI. By co-registering post-operative images of individual animals to a common stereotaxic template, targeting accuracy is quantified. Two commonly used neuromodulation regions were used as targets. Target localization errors showed not only variability, but also inaccuracy in targeting. Only about 30% of electrodes were within the subnucleus structure that was targeted and a-specific adverse effects were also noted. Shifting from invasive/subjective 2D histology towards objective in vivo 3D imaging-based assessment of targeting accuracy may benefit a more effective use of the experimental data by excluding off-target cases early in the study.

Extensional fault geometry and its flexural isostatic response during the formation of the Iberia - Newfoundland conjugate rifted margins

Science.gov (United States)

Gómez-Romeu, Júlia; Kusznir, Nick; Manatschal, Gianreto; Roberts, Alan

2017-04-01

Despite magma-poor rifted margins having been extensively studied for the last 20 years, the evolution of extensional fault geometry and the flexural isostatic response to faulting remain still debated topics. We investigate how the flexural isostatic response to faulting controls the structural development of the distal part of rifted margins in the hyper-extended domain and the resulting sedimentary record. In particular we address an important question concerning the geometry and evolution of extensional faults within distal hyper-extended continental crust; are the seismically observed extensional fault blocks in this region allochthons from the upper plate or are they autochthons of the lower plate? In order to achieve our aim we focus on the west Iberian rifted continental margin along the TGS and LG12 seismic profiles. Our strategy is to use a kinematic forward model (RIFTER) to model the tectonic and stratigraphic development of the west Iberia margin along TGS-LG12 and quantitatively test and calibrate the model against breakup paleo-bathymetry, crustal basement thickness and well data. RIFTER incorporates the flexural isostatic response to extensional faulting, crustal thinning, lithosphere thermal loads, sedimentation and erosion. The model predicts the structural and stratigraphic consequences of recursive sequential faulting and sedimentation. The target data used to constrain model predictions consists of two components: (i) gravity anomaly inversion is used to determine Moho depth, crustal basement thickness and continental lithosphere thinning and (ii) reverse post-rift subsidence modelling consisting of flexural backstripping, decompaction and reverse post-rift thermal subsidence modelling is used to give paleo-bathymetry at breakup time. We show that successful modelling of the structural and stratigraphic development of the TGS-LG12 Iberian margin transect also requires the simultaneous modelling of the Newfoundland conjugate margin, which we

Comparison of safety margins for leak-before-break assessment of 500 MWe PHWR straight pipes: using contemporary techniques

International Nuclear Information System (INIS)

Rastogi, Rohit; Bhasin, Vivek; Kushwaha, H.S.

1998-01-01

The Leak Before Break (LBB) analysis of Primary Heat Transport (PHT) Piping of 500 MWe Indian PHWR is being performed using different well established techniques like R6 method (Nuclear Electric UK) and J-Tearing based methods (USNRC). These methods show that PHT piping has required safety margins and can be qualified for LBB. These analysis also showed that the piping has high fracture toughness and plastic collapse is the dominant mode of failure. To enhance the confidence in the results obtained from the above methods, further studies were done on the PHT piping. Procedures which predicted margins against plastic collapse were used. The analysis procedures used were Modified Limit Load Method, MPA Method (both from Germany), Moments Method (from Italy) and the Z-Factor method given in ASME Boiler and Pressure Vessel Code. The safety margins obtained from these analysis satisfied the LBB requirements. A table was generated which compared the safety margins obtained using all the above mentioned procedures. This report presents the results of this study. (author)

Does insecticide drift adversely affect grasshoppers (Orthoptera: Saltatoria) in field margins? A case study combining laboratory acute toxicity testing with field monitoring data.

Science.gov (United States)

Bundschuh, Rebecca; Schmitz, Juliane; Bundschuh, Mirco; Brühl, Carsten Albrecht

2012-08-01

The current terrestrial risk assessment of insecticides regarding nontarget arthropods considers exclusively beneficial organisms, whereas herbivorous insects, such as grasshoppers, are ignored. However, grasshoppers living in field margins or meadows adjacent to crops may potentially be exposed to insecticides due to contact with or ingestion of contaminated food. Therefore, the present study assessed effects of five active ingredients of insecticides (dimethoate, pirimicarb, imidacloprid, lambda-cyhalothrin, and deltamethrin) on the survival of Chorthippus sp. grasshopper nymphs by considering two routes of exposure (contact and oral). The experiments were accompanied by monitoring field margins that neighbored cereals, vineyards, and orchards. Grasslands were used as reference sites. The laboratory toxicity tests revealed a sensitivity of grasshoppers with regard to the insecticides tested in the present study similar to that of the standard test species used in arthropod risk assessments. In the field monitoring program, increasing grasshopper densities were detected with increasing field margin width next to cereals and vineyards, but densities remained low over the whole range of field margins from 0.5 to 20 m next to orchards. Grasshopper densities equivalent to those of grassland sites were only observed in field margins exceeding 9 m in width, except for field margins next to orchards. These results may indicate that current insecticide risk assessments are insufficiently protective for grasshoppers in field margins. Copyright © 2012 SETAC.

The marginal band system in nymphalid butterfly wings.

Science.gov (United States)

Taira, Wataru; Kinjo, Seira; Otaki, Joji M

2015-01-01

Butterfly wing color patterns are highly complex and diverse, but they are believed to be derived from the nymphalid groundplan, which is composed of several color pattern systems. Among these pattern systems, the marginal band system, including marginal and submarginal bands, has rarely been studied. Here, we examined the color pattern diversity of the marginal band system among nymphalid butterflies. Marginal and submarginal bands are usually expressed as a pair of linear bands aligned with the wing margin. However, a submarginal band can be expressed as a broken band, an elongated oval, or a single dot. The marginal focus, usually a white dot at the middle of a wing compartment along the wing edge, corresponds to the pupal edge spot, one of the pupal cuticle spots that signify the locations of color pattern organizing centers. A marginal band can be expressed as a semicircle, an elongated oval, or a pair of eyespot-like structures, which suggest the organizing activity of the marginal focus. Physical damage at the pupal edge spot leads to distal dislocation of the submarginal band in Junonia almana and in Vanessa indica, suggesting that the marginal focus functions as an organizing center for the marginal band system. Taken together, we conclude that the marginal band system is developmentally equivalent to other symmetry systems. Additionally, the marginal band is likely a core element and the submarginal band a paracore element of the marginal band system, and both bands are primarily specified by the marginal focus organizing center.

MARGINS: Toward a novel science plan

Science.gov (United States)

Mutter, John C.

A science plan to study continental margins has been in the works for the past 3 years, with almost 200 Earth scientists from a wide variety of disciplines gathering at meetings and workshops. Most geological hazards and resources are found at continental margins, yet our understanding of the processes that shape the margins is meager.In formulating this MARGINS research initiative, fundamental issues concerning our understanding of basic Earth-forming processes have arisen. It is clear that a business-as-usual approach will not solve the class of problems defined by the MARGINS program; the solutions demand approaches different from those used in the past. In many cases, a different class of experiment will be required, one that is well beyond the capability of individual principle investigators to undertake on their own. In most cases, broadly based interdisciplinary studies will be needed.

Evaluation and comparison of the marginal adaptation of two different substructure materials.

Science.gov (United States)

Karaman, Tahir; Ulku, Sabiha Zelal; Zengingul, Ali Ihsan; Guven, Sedat; Eratilla, Veysel; Sumer, Ebru

2015-06-01

In this study, we aimed to evaluate the amount of marginal gap with two different substructure materials using identical margin preparations. Twenty stainless steel models with a chamfer were prepared with a CNC device. Marginal gap measurements of the galvano copings on these stainless steel models and Co-Cr copings obtained by a laser-sintering method were made with a stereomicroscope device before and after the cementation process and surface properties were evaluated by scanning electron microscopy (SEM). A dependent t-test was used to compare the mean of the two groups for normally distributed data, and two-way variance analysis was used for more than two data sets. Pearson's correlation analysis was also performed to assess relationships between variables. According to the results obtained, the marginal gap in the galvano copings before cementation was measured as, on average, 24.47 ± 5.82 µm before and 35.11 ± 6.52 µm after cementation; in the laser-sintered Co-Cr structure, it was, on average, 60.45 ± 8.87 µm before and 69.33 ± 9.03 µm after cementation. A highly significant difference (Pcementation were within the clinically acceptable level. The smallest marginal gaps occurred with the use of galvano copings.

An assessment of interfractional uterine and cervical motion: Implications for radiotherapy target volume definition in gynaecological cancer

International Nuclear Information System (INIS)

Taylor, Alexandra; Powell, Melanie E.B.

2008-01-01

Purpose: To assess interfractional movement of the uterus and cervix in patients with gynaecological cancer to aid selection of the internal margin for radiotherapy target volumes. Methods and materials: Thirty-three patients with gynaecological cancer had an MRI scan performed on two consecutive days. The two sets of T2-weighted axial images were co-registered, and the uterus and cervix outlined on each scan. Points were identified on the anterior uterine body (Point U), posterior cervix (Point C) and upper vagina (Point V). The displacement of each point in the antero-posterior (AP), supero-inferior (SI) and lateral directions between the two scans was measured. The changes in point position and uterine body angle were correlated with bladder volume and rectal diameter. Results: The mean difference (±1SD) in Point U position was 7 mm (±9.0) in the AP direction, 7.1 mm (±6.8) SI and 0.8 mm (±1.3) laterally. Mean Point C displacement was 4.1 mm (±4.4) SI, 2.7 mm (±2.8) AP, 0.3 (±0.8) laterally, and Point V was 2.6 mm (±3.0) AP and 0.3 mm (±1.0) laterally. There was correlation for uterine SI movement in relation to bladder filling, and for cervical and vaginal AP movement in relation to rectal filling. Conclusion: Large movements of the uterus can occur, particularly in the superior-inferior and anterior-posterior directions, but cervical displacement is less marked. Rectal filling may affect cervical position, while bladder filling has more impact on uterine body position, highlighting the need for specific instructions on bladder and rectal filling for treatment. We propose an asymmetrical margin with CTV-PTV expansion of the uterus, cervix and upper vagina of 15 mm AP, 15 mm SI and 7 mm laterally and expansion of the nodal regions and parametria by 7 mm in all directions

Level of Alkenylbenzenes in Parsley and Dill Based Teas and Associated Risk Assessment Using the Margin of Exposure Approach.

Science.gov (United States)

Alajlouni, Abdalmajeed M; Al-Malahmeh, Amer J; Isnaeni, Farida Nur; Wesseling, Sebastiaan; Vervoort, Jacques; Rietjens, Ivonne M C M

2016-11-16

Risk assessment of parsley and dill based teas that contain alkenylbenzenes was performed. To this end the estimated daily intake (EDI) of alkenylbenzenes resulting from use of the teas was quantified. Since most teas appeared to contain more than one alkenylbenzene, a combined risk assessment was performed based on equal potency of all alkenylbenzenes or using a so-called toxic equivalency (TEQ) approach through defining toxic equivalency factors (TEFs) for the different alkenylbenzenes. The EDI values resulting from consuming one cup of tea a day were 0.2-10.1 μg/kg bw for the individual alkenylbenzenes, 0.6-13.1 μg/kg bw for the sum of the alkenylbenzenes, and 0.3-10.7 μg safrole equiv/kg bw for the sum of alkenylbenzenes when expressed in safrole equivalents. The margin of exposure (MOE) values obtained were generally <10000, indicating a concern if the teas would be consumed on a daily basis over longer periods of time.

Reliabilityy and operating margins of LWR fuels

International Nuclear Information System (INIS)

Strasser, A.A.; Lindquist, K.O.

1977-01-01

The margins to fuel thermal operating limits under normal and accident conditions are key to plant operating flexibility and impact on availability and capacity factor. Fuel performance problems that do not result in clad breach, can reduce these margins. However, most have or can be solved with design changes. Regulatory changes have been major factors in eroding these margins. Various methods for regaining the margins are discussed

Impact of margin on tumour and normal tissue dosimetry in patients treated with IMRT using an endorectal balloon for prostate immobilization

International Nuclear Information System (INIS)

Ahmad, S.

2004-01-01

Full text: In treatment of prostate cancer with IMRT (Intensity Modulated Radiation Therapy), clinical target volume margin is determined by organ motion and set-up error. However, the margin width that achieves the desired dose escalation while minimizing normal tissue exposure is dependent upon the patient immobilization and/or organ localization techniques. In this study, we compare the impact of margin width on the dosimetry of tumour and normal tissues using the endorectal balloon for prostate immobilization. IMRT plans were generated for ten patients using margin widths of 0, 3, 5, 8 and 10 mm. Patients had a planning CT scan in the prone position with an endorectal balloon filled with 100 cc of air for prostate immobilization. The Corvus version 3.0.11 was used for treatment planning. The dose for the prostate and seminal vesicles was 70 Gy in 2 Gy per fractions, prescribed at the 83% isodose line. Dose restrictions to normal tissues were as follows: 33% of bladder was allowed to receive above 65 Gy, 15% of rectum above 68 Gy and 10% of femurs above 45 Gy. Analysis of Variance was used to compare the target and normal tissue doses. Tumour control probability and normal tissue complication probability calculations are currently being performed and will be presented. The mean doses ranged from 73.93 to 75.31 Gy for the prostate and from 73.71 to 75.31 Gy for the seminal vesicles. A 10 mm margin produced significantly lower mean doses compared to 0 or 5 mm for both targets (prostate p 0.062). For bladder and rectum the mean doses ranged from 18.49 to 22.30 Gy (p=0.605) and from 29.34 to 31.33 Gy (p=0.135), respectively, while the percent rectal volumes above 68 Gy were significantly higher for margins of 5, 8 and 10 mm (p<0.006) ranging from 10.72% to 15.81%. Mean doses to the femurs and pelvis were significantly higher for 8 and 10 mm margins, ranging from 20.9 to 29.39 Gy for femurs (p<0.015) and from 15.05 to 19.98 Gy for pelvis (p<0.0005). Also the percent

Assessment of dose inhomogeneity at target level by in vivo dosimetry

International Nuclear Information System (INIS)

Leunens, G.; Verstraete, J.; Dutreix, A.; Schueren, E. van der

1992-01-01

Inhomogeneity of dose delivered to the target volume due to irregular body surface and tissue densities remains in many cases unknown, since dose distribution is calculated for most radiation treatments in only one transverse section and assuming the patient to be water equivalent. In this study transmission and target absorbed dose homogeneity is assessed for 11 head-and-neck cancer treatments by in vivo measurements with silicon diodes. Besides the dose to specification point, the dose delivered to 2-4 off-axis points in midline sagittal plane is estimated from entrance and exit dose measurements. Simultaneously made portal films allow to identify anatomical structures passed by the beam before reaching exit diode. Mean deviation from expected transmission is -6.8% for bone, +6% for air cavities and -2.5% for soft tissue. At midplane, mean deviations from expected target dose are respectively -3.5%, +2.3% and -1.9%. Deviations from prescribed dose are larger than 5% in 12/39 target points. Accuracy requirements in target dose delivery of plus or minus 5%, as proposed by ICRU, cannot be fulfilled in 7/11 patients and is mostly due to irregular body contour and tissue densities. as only a limited number of points are considered, inhomogeneity in dose delivered throughout whole irradiated volume is underestimated, as is illustrated from exit dose profiles obtained from portal image. Besides its tremendous value as a quality assurance procedure, in vivo dose measurements are shown to be a valid method for assessing dose delivered to irradiated tissues when dose computations are assumed to be inaccurate or even impossible in current practice. (author). 21 refs., 8 figs., 1 tab

An assessment of independent component analysis for detection of military targets from hyperspectral images

Science.gov (United States)

Tiwari, K. C.; Arora, M. K.; Singh, D.

2011-10-01

Hyperspectral data acquired over hundreds of narrow contiguous wavelength bands are extremely suitable for target detection due to their high spectral resolution. Though spectral response of every material is expected to be unique, but in practice, it exhibits variations, which is known as spectral variability. Most target detection algorithms depend on spectral modelling using a priori available target spectra In practice, target spectra is, however, seldom available a priori. Independent component analysis (ICA) is a new evolving technique that aims at finding out components which are statistically independent or as independent as possible. The technique therefore has the potential of being used for target detection applications. A assessment of target detection from hyperspectral images using ICA and other algorithms based on spectral modelling may be of immense interest, since ICA does not require a priori target information. The aim of this paper is, thus, to assess the potential of ICA based algorithm vis a vis other prevailing algorithms for military target detection. Four spectral matching algorithms namely Orthogonal Subspace Projection (OSP), Constrained Energy Minimisation (CEM), Spectral Angle Mapper (SAM) and Spectral Correlation Mapper (SCM), and four anomaly detection algorithms namely OSP anomaly detector (OSPAD), Reed-Xiaoli anomaly detector (RXD), Uniform Target Detector (UTD) and a combination of Reed-Xiaoli anomaly detector and Uniform Target Detector (RXD-UTD) were considered. The experiments were conducted using a set of synthetic and AVIRIS hyperspectral images containing aircrafts as military targets. A comparison of true positive and false positive rates of target detections obtained from ICA and other algorithms plotted on a receiver operating curves (ROC) space indicates the superior performance of the ICA over other algorithms.

Enhancing the diversity of breeding invertebrates within field margins of intensively managed grassland: Effects of alternative management practices.

Science.gov (United States)

Fritch, Rochelle A; Sheridan, Helen; Finn, John A; McCormack, Stephen; Ó hUallacháin, Daire

2017-11-01

Severe declines in biodiversity have been well documented for many taxonomic groups due to intensification of agricultural practices. Establishment and appropriate management of arable field margins can improve the diversity and abundance of invertebrate groups; however, there is much less research on field margins within grassland systems. Three grassland field margin treatments (fencing off the existing vegetation "fenced"; fencing with rotavation and natural regeneration "rotavated" and; fencing with rotavation and seeding "seeded") were compared to a grazed control in the adjacent intensively managed pasture. Invertebrates were sampled using emergence traps to investigate species breeding and overwintering within the margins. Using a manipulation experiment, we tested whether the removal of grazing pressure and nutrient inputs would increase the abundance and richness of breeding invertebrates within grassland field margins. We also tested whether field margin establishment treatments, with their different vegetation communities, would change the abundance and richness of breeding invertebrates in the field margins. Exclusion of grazing and nutrient inputs led to increased abundance and richness in nearly all invertebrate groups that we sampled. However, there were more complex effects of field margin establishment treatment on the abundance and richness of invertebrate taxa. Each of the three establishment treatments supported a distinct invertebrate community. The removal of grazing from grassland field margins provided a greater range of overwintering/breeding habitat for invertebrates. We demonstrate the capacity of field margin establishment to increase the abundance and richness in nearly all invertebrate groups in study plots that were located on previously more depauperate areas of intensively managed grassland. These results from grassland field margins provide evidence to support practical actions that can inform Greening (Pillar 1) and agri

Work, organisational practices, and margin of manoeuver during work reintegration.

Science.gov (United States)

O'Hagan, Fergal

2017-09-29

Many individuals of working age experience cardiovascular disease and are disabled from work as a result. The majority of research in cardiac work disability has focused on individual biological and psychological factors influencing work disability despite evidence of the importance of social context in work disability. In this article, the focus is on work and organisational features influencing the leeway (margin of manoeuvre) workers are afforded during work reintegration. A qualitative method was used. A large auto manufacturing plant was selected owing to work, organisational, and worker characteristics. Workplace context was assessed through site visits and meetings with stakeholders including occupational health, human resources and union personnel and a review of collective agreement provisions relating to seniority, benefits and accommodation. Worker experience was assessed using a series of in-depth interviews with workers (n = 12) returning to work at the plant following disabling cardiac illness. Data was analysed using qualitative content analysis. Workers demonstrated variable levels of adjustment to the workplace that could be related to production expectations and work design. Policies and practices around electronic rate monitoring, seniority and accommodation, and disability management practices affected the buffer available to workers to adjust to the workplace. Work qualities and organisational resources establish a margin of manoeuver for work reintegration efforts. Practitioners need to inform themselves of the constraints on work accommodation imposed by work organisation and collective agreements. Organisations and labour need to reconsider policies and practices that creates unequal accommodation conditions for disabled workers. Implications for rehabilitation Margin of manoeuvre offers a framework for evaluating and structuring work reintegration programmes. Assessing initial conditions for productivity expectations, context and ways

A quantitative evaluation of seismic margin of typical sodium piping

International Nuclear Information System (INIS)

Morishita, Masaki

1999-05-01

It is widely recognized that the current seismic design methods for piping involve a large amount of safety margin. From this viewpoint, a series of seismic analyses and evaluations with various design codes were made on typical LMFBR main sodium piping systems. Actual capability against seismic loads were also estimated on the piping systems. Margins contained in the current codes were quantified based on these results, and potential benefits and impacts to the piping seismic design were assessed on possible mitigation of the current code allowables. From the study, the following points were clarified; 1) A combination of inelastic time history analysis and true (without margin)strength capability allows several to twenty times as large seismic load compared with the allowable load with the current methods. 2) The new rule of the ASME is relatively compatible with the results of inelastic analysis evaluation. Hence, this new rule might be a goal for the mitigation of seismic design rule. 3) With this mitigation, seismic design accommodation such as equipping with a large number of seismic supports may become unnecessary. (author)

Marginal leakage of two newer glass-ionomer-based sealant materials assessed using micro-CT.

NARCIS (Netherlands)

Chen, X.; Cuijpers, V.M.J.I.; Fan, M.; Frencken, J.E.F.M.

2010-01-01

OBJECTIVES: To test newer glass-ionomer-based materials as sealant materials. One glass-ionomer sealant was light-cured to obtain an early setting reaction. The null-hypothesis tested was: there is no difference in marginal leakage of sealants produced with high-viscosity glass-ionomer, with and

Marginal zone in femoral head avascular necrosis: scintigraphic characteristics and clinical prognostic value

International Nuclear Information System (INIS)

Milcinski, M.; Sedonja, I.; Dolinar, D.; Jevtic, V.

2002-01-01

Aim: Marginal zone, seen on magnetic resonance imaging (MRI) in femoral head avascular necrosis, consists of granulation tissue and sclerosis at the junction of necrotic and normal bone. Prognostic value of this finding is not clear. Aim of our study was to evaluate osteoblastic activity of marginal zone with bone scintigraphy and to assess prognostic importance of marginal zone for further evolution of femoral head necrosis. Material and methods: MRI was performed in 37 hips in 26 patients (17 m, 9 f, 20-64 y, mean 42,9 y) with Ficat 0-II avascular necrosis (SE T1W, STIR and SE T1W FAT.SAT after Gd DTPA in the coronal plane and GE FLASH in the sagittal plane). In 26 hips of 17 patients planar and pinhole scintigraphy with 99mTc-DPD was performed. Results: On MRI, marginal zone divided necrotic and normal bone in 26/37 (70,3%) hips, in 14/26 it was thin (2% of femoral head diameter or less), but in 12/26 it was wide (more than 2% of femoral head diameter). In 11/37 (29,7%) hips marginal zone was not seen. Pinhole scintigraphy was performed in 26 hips; in all 10/10 (100%) hips with wide marginal zone, seen on MRI, increased osteoblastic activity was detected, while only in 1/9 (11,1%) hips with thin marginal zone on MRI osteoblastic activity was increased. Patients were followed 1 to 5 years (mean 2,2 y). In hips without marginal zone no collapse of femoral head was seen until now, in 2/11 (18,2%) femoral heads MRI and clinical regression was observed. Ten of 12 lesions with wide marginal zone (83,3 %) collapsed 0,25 to 2,5 (mean 1) years after onset of pain. Two of 12 lesions with wide marginal zone (16,7%) have not collapsed until now. From lesions with thin marginal zone, 4/14 (28,6 %) collapsed 0,7 to 3 (mean 1,9) years after onset of pain, 10/14 (71,4%) did not collapse until now. Conclusion: Increased osteoblastic activity in wide marginal zone between necrotic and vital bone in hip avascular necrosis is bad prognostic factor for femoral head collapse

Optimal MRI methods for direct stereotactic targeting of the subthalamic nucleus and globus pallidus

International Nuclear Information System (INIS)

O'Gorman, Ruth L.; Shmueli, Karin; Ashkan, Keyoumars; Selway, Richard P.; Samuel, Michael; Lythgoe, David J.; Shahidiani, Asal; Wastling, Stephen J.; Footman, Michelle; Jarosz, Jozef

2011-01-01

Reliable identification of the subthalamic nucleus (STN) and globus pallidus interna (GPi) is critical for deep brain stimulation (DBS) of these structures. The purpose of this study was to compare the visibility of the STN and GPi with various MRI techniques and to assess the suitability of each technique for direct stereotactic targeting. MR images were acquired from nine volunteers with T2- and proton density-weighted (PD-W) fast spin echo, susceptibility-weighted imaging (SWI), phase-sensitive inversion recovery and quantitative T1, T2 and T2 * mapping sequences. Contrast-to-noise ratios (CNR) for the STN and GPi were calculated for all sequences. Targeting errors on SWI were evaluated on magnetic susceptibility maps. The sequences demonstrating the best conspicuity of DBS target structures (SWI and T2*) were then applied to ten patients with movement disorders, and the CNRs for these techniques were assessed. SWI offers the highest CNR for the STN, but standard PD-W images provide the best CNR for the pallidum. Susceptibility maps indicated that the GPi margins may be shifted slightly on SWI, although no shifts were seen for the STN. SWI may improve the visibility of the STN on pre-operative MRI, potentially improving the accuracy of direct stereotactic targeting. (orig.)

Marginal cost application in the power industry

International Nuclear Information System (INIS)

Twardy, L.; Rusak, H.

1994-01-01

Two kind of marginal costs, the short-run and the long-run, are defined. The former are applied in conditions when the load increase is not accompanied neither by the increase of the transmission capacity not the installed capacity while the latter assume new investments to expand the power system. The long-run marginal costs be used to forecast optimized development of the system. They contain two main components: the marginal costs of capacity and the marginal costs of energy. When the long-run marginal costs are calculated, each component is considered for particular voltage levels, seasons of the year, hours of the day - selected depending on the system reliability factor as well as on its load level. In the market economy countries the long-run marginal costs can be used for setting up the electric energy tariffs. (author). 7 refs, 11 figs

Safety margin in irradiation of colorectal liver metastases: assessment of the control dose of micrometastases

Directory of Open Access Journals (Sweden)

Seidensticker Max

2010-03-01

Full Text Available Abstract Backround Micrometastases of colorectal liver metastases are present in up to 50% of lesions. In this study we sought to determine the threshold dose for local control of occult micrometastases in patients undergoing CT (computed tomography-guided brachytherapy of colorectal liver metastases. Materials and methods Nineteen patients demonstrated 34 local tumor recurrences originating from micrometastases after CT-guided brachytherapy of 27 colorectal liver metastases. We considered a local tumor recurrence as originating from a micrometastasis if tumor regrowth occurred adjacent to a formerly irradiated lesion and the distance of the 3D isocenter of the new lesion was ≤ 23.5 mm from the previous tumor margin. Follow-up MRI was fused with the planning-CT and dosimetry data. Two reviewers independently indicated the dose exposure at the isocenter of the micrometastases. Statistical analysis included an analysis of variance (ANOVA using backward selection. 95% tolerance intervals with coverage of 87.5 and 75% of the data of the normal distribution were calculated. Results The median distance of the micrometastases to the margin of the originating colorectal metastases was 8.75 mm (1-21 mm. Dose exposure at the isocenter was 12.25 Gy (7-19.8 in median. We stratified according to the distance from the isocenter to the initial tumor margin: ≤ 9 mm, > 9-15 mm and > 15 mm. The median dose in the according isocenters was 13.18, 11.6 and 11.85 Gy. The threshold dose failing to prevent micrometastasis growth was sigificantly higher in a subgroup of lesions with ≤ 9 mm distance as compared to > 15 mm (13.18 vs 11.85 Gy. Adjuvant chemotherapy correlated with greater distance of micrometastasis growth to the tumor but not with the threshold dose. Conclusion To prevent loss of local tumor control by continuous growth of micrometastases a threshold dose of 15,4 Gy (single fraction should be delivered at a distance of 21 mm to the gross tumor

Pancreatic cancer cell detection by targeted lipid microbubbles and multiphoton imaging

Science.gov (United States)

Cromey, Benjamin; McDaniel, Ashley; Matsunaga, Terry; Vagner, Josef; Kieu, Khanh Quoc; Banerjee, Bhaskar

2018-04-01

Surgical resection of pancreatic cancer represents the only chance of cure and long-term survival in this common disease. Unfortunately, determination of a cancer-free margin at surgery is based on one or two tiny frozen section biopsies, which is far from ideal. Not surprisingly, cancer is usually left behind and is responsible for metastatic disease. We demonstrate a method of receptor-targeted imaging using peptide ligands, lipid microbubbles, and multiphoton microscopy that could lead to a fast and accurate way of examining the entire cut surface during surgery. Using a plectin-targeted microbubble, we performed a blinded in-vitro study to demonstrate avid binding of targeted microbubbles to pancreatic cancer cells but not noncancerous cell lines. Further work should lead to a much-needed point-of-care diagnostic test for determining clean margins in oncologic surgery.

High precision conformal radiotherapy employing conservative margins in childhood benign and low-grade brain tumours

International Nuclear Information System (INIS)

Jalali, Rakesh; Budrukkar, Ashwini; Sarin, Rajiv; Sharma, Dayananda S.

2005-01-01

Background and purpose: To report local control and follow up outcome data of high precision conformal radiotherapy in childhood brain tumours. Materials and methods: Between December 1999 and December 2002, 26 children (17 boys and 9 girls, median age 11.5 years) with incompletely excised or recurrent benign and low-grade brain tumours [13 craniopharyngiomas, 11 low-grade gliomas (LGG) and 2 others] were treated with three-dimensional (3D) conformal radiotherapy (CRT) (12 patients) and stereotactic conformal radiotherapy (SCRT) (14 patients). Gross tumour volume (GTV) included neuro-imaging based visible tumour and/or resected tumour bed. Clinical target volume (CTV) consisted of GTV + 5 mm margin and planning target volume (PTV) consisted of additional 5 mm margin for CRT and 2 mm for SCRT. Treatment was delivered with 3-9 conformal fixed fields to a median dose of 54 Gy/30 fractions. Results: The actuarial 2 and 3 year disease free and overall survival was 96 and 100%, respectively (median follow up: 25 months, range 12-47 months). Radiological follow up available in 25 patients revealed complete response in 1, partial regression in 10, stable disease in 13 and progression in 1 patient (within the CTV). One patient with craniopharyngioma on a routine imaging revealed a mild asymptomatic cyst enlargement, which resolved with conservative management. A patient with chiasmatic glioma developed cystic degeneration and hydrocephalus 9 months after SCRT requiring cyst drainage and placement of a ventriculoperitoneal shunt. Conclusion: High-precision conformal techniques delivering irradiation to a computer generated target volume employing 7-10 mm 3D margins beyond the visible tumour and/or resected tumour bed appear to be safe in children with incompletely resected or recurrent benign and low-grade brain tumours, based on these data

Workers' marginal costs of commuting

DEFF Research Database (Denmark)

van Ommeren, Jos; Fosgerau, Mogens

2009-01-01

This paper applies a dynamic search model to estimate workers' marginal costs of commuting, including monetary and time costs. Using data on workers' job search activity as well as moving behaviour, for the Netherlands, we provide evidence that, on average, workers' marginal costs of one hour...

Meta-Analysis of Correlations Between Marginal Bone Resorption and High Insertion Torque of Dental Implants.

Science.gov (United States)

Li, Haoyan; Liang, Yongqiang; Zheng, Qiang

2015-01-01

To evaluate correlations between marginal bone resorption and high insertion torque value (> 50 Ncm) of dental implants and to assess the significance of immediate and early/conventional loading of implants under a certain range torque value. Specific inclusion and exclusion criteria were used to retrieve eligible articles from Ovid, PubMed, and EBSCO up to December 2013. Screening of eligible studies, quality assessment, and data extraction were conducted in duplicate. The results were expressed as random/fixed-effects models using weighted mean differences for continuous outcomes with 95% confidence intervals. Initially, 154 articles were selected (11 from Ovid, 112 from PubMed, and 31 from EBSCO). After exclusion of duplicate articles and articles that did not meet the inclusion criteria, six clinical studies were selected. Assessment of P values revealed that correlations between marginal bone resorption and high insertion torque were not statistically significant and that there was no difference between immediately versus early/conventionally loaded implants under a certain range of torque. None of the meta-analyses revealed any statistically significant differences between high insertion torque and conventional insertion torque in terms of effects on marginal bone resorption.

Pathology of nodal marginal zone lymphomas.

Science.gov (United States)

Pileri, Stefano; Ponzoni, Maurilio

Nodal marginal zone B cell lymphomas (NMZLs) are a rare group of lymphoid disorders part of the spectrum of marginal zone B-cell lymphomas, which encompass splenic marginal one B-cell lymphoma (SMZL) and extra nodal marginal zone of B-cell lymphoma (EMZL), often of MALT-type. Two clinicopathological forms of NMZL are recognized: adult-type and pediatric-type, respectively. NMZLs show overlapping features with other types of MZ, but distinctive features as well. In this review, we will focus on the salient distinguishing features of NMZL mostly under morphological/immunophenotypical/molecular perspectives in views of the recent acquisitions and forthcoming updated 2016 WHO classification of lymphoid malignancies. Copyright © 2016 Elsevier Ltd. All rights reserved.

An IGRT margin concept for pelvic lymph nodes in high-risk prostate cancer

Energy Technology Data Exchange (ETDEWEB)

Groher, M.; Kopp, P.; Deutschmann, H.; Sedlmayer, F.; Wolf, Frank [Paracelsus Medical University of Salzburg, Department of Radiation Oncology, St. Johanns-Spital, Salzburg (Austria); Drerup, M. [Paracelsus Medical University of Salzburg, Department of Urology, St. Johanns-Spital, Salzburg (Austria)

2017-09-15

Gold-marker-based image-guided radiation therapy (IGRT) of the prostate allows to correct for inter- and intrafraction motion and therefore to safely reduce margins for the prostate planning target volume (PTV). However, pelvic PTVs, when coadministered in a single plan (registered to gold markers [GM]), require reassessment of the margin concept since prostate movement is independent from the pelvic bony anatomy to which the lymphatics are usually referenced to. We have therefore revisited prostate translational movement relative to the bony anatomy to obtain adequate margins for the pelvic PTVs compensating mismatch resulting from referencing pelvic target volumes to GMs in the prostate. Prostate movement was analyzed in a set of 28 patients (25 fractions each, totaling in 684 fractions) and the required margins calculated for the pelvic PTVs according to Van Herk's margin formula M = 2.5 Σ + 1.64 (σ{sup '}-σ{sub p}). The overall mean prostate movement relative to bony anatomy was 0.9 ± 3.1, 0.6 ± 3.4, and 0.0 ± 0.7 mm in anterior/posterior (A/P), inferior/superior (I/S) and left/right (L/R) direction, respectively. Calculated margins to compensate for the resulting mismatch to bony anatomy were 9/9/2 mm in A/P, I/S, and L/R direction and 10/11/6 mm if an additional residual error of 2 mm was assumed. GM-based IGRT for pelvic PTVs is feasible if margins are adapted accordingly. Margins could be reduced further if systematic errors which are introduced during the planning CT were eliminated. (orig.) [German] Eine Goldmarker-(GM-)basierte, bildgefuehrte Radiotherapie der Prostata ermoeglicht inter- und intrafraktionelle Bewegungen auszugleichen und somit Sicherheitsraender der Planungszielvolumina (PTV) zu minimieren. Dies gilt jedoch nicht fuer Zielvolumina des pelvinen Lymphabflusses, wenn diese im Rahmen eines simultan integrierten Boost-Konzepts im selben Plan verabreicht werden. Da Bewegungen der Prostata und des Lymphabflusses unabhaengig

Biodiversity and agro-ecology in field margins.

Science.gov (United States)

De Cauwer, B; Reheul, D; Nijs, I; Milbau, A

2005-01-01

This multidisciplinary study investigates agro-ecological functions (nature conservation, agriculture, environment) and implications of newly created, mown sown and unsown field margin strips installed on ex-arable land to increase biodiversity. From conservational concern, the development of species rich field margin strips was not strongly affected by the installed type of margin strip since species diversity converged over time, whether strips were sown or not. Convergence between unsown and sown margin strips occurred also in terms of species composition: unsown and sown strips became similar over time. Mowing without removal of cuttings significantly reduced species richness, yielded more grassy margin strips and delayed similarity in species composition between sown and unsown margin strips. Species richness on the longer term was not significantly affected by light regime nor by disturbance despite significant temporary effects shortly after the disturbance event. On the contrary vegetation composition in terms of importance of functional groups changed after disturbance: the share of spontaneous species within functional groups increased resulting in higher similarity between the sown and unsown vegetation. Furthermore risk of invasion was highest in the disturbed unsown community on the unshaded side of a tree lane. A positive effect of botanical diversity on insect number and diversity was found. However the effects of botanical diversity on insect number was mediated by light regime. At high light availability differences between plant communities were more pronounced compared to low light availablilty. The abundance of some insect families was dependent on the vegetation composition. Furthermore light availability significantly influenced insect diversity as well as the spatial distribution of families. From agricultural concern, installing margin strips by sowing a species mixture and a mowing regime with removal of cuttings are good practices to

Population and patient-specific target margins for 4D adaptive radiotherapy to account for intra- and inter-fraction variation in lung tumour position

International Nuclear Information System (INIS)

Hugo, Geoffrey D; Di Yan; Jian Liang

2007-01-01

In this work, five 4D image-guidance strategies (two population, an offline adaptive and two online strategies) were evaluated that compensated for both inter- and intra-fraction variability such as changes to the baseline tumour position and respiratory pattern. None of the strategies required active motion compensation such as gating or tracking; all strategies simulated a free-breathing-based treatment technique. Online kilovoltage fluoroscopy was acquired for eight patients with lung tumours, and used to construct inter- and intra-fraction tumour position variability models. Planning was performed on a mid-ventilation image acquired from a respiration-correlated CT scan. The blurring effect of tumour position variability was included in the dose calculation by convolution. CTV to PTV margins were calculated for variability in the cranio-caudal direction. A population margin of 9.0 ± 0.7 mm was required to account for setup error and respiration in the study population without the use of image-guidance. The greatest mean margin reduction was introduced by the offline adaptive strategy. A daily online correction strategy produced a small reduction (1.6 mm) in the mean margin from the offline strategy. Adaptively correcting for an inter-fraction change in the respiratory pattern had little effect on margin size due to most patients having only small daily changes in the respiratory pattern. A daily online correction strategy would be useful for patients who exhibit large variations in the daily mean tumour position, while an offline adaptive strategy is more applicable to patients with less variation

Advancing Understanding of Earthquakes by Drilling an Eroding Convergent Margin

Science.gov (United States)

von Huene, R.; Vannucchi, P.; Ranero, C. R.

2010-12-01

perhaps geologically than the Nankai margin. The developing Central American countries do not have the resources to contribute to IODP but this should not deter acquiring the scientific insights proposed in CRISP considering the broader scientific benefits. Such benefits include the first sampling and instrumentation of an actively eroding plate interface and drilling near or into an earthquake asperity. Drilling an eroding margin should significantly advance understanding of subduction zone fault mechanisms and help improve assessment of future hazardous earthquakes and tsunamis.

Biomechanical Effect of Margin Convergence Techniques: Quantitative Assessment of Supraspinatus Muscle Stiffness.

Directory of Open Access Journals (Sweden)

Taku Hatta

Full Text Available Although the margin convergence (MC technique has been recognized as an option for rotator cuff repair, little is known about the biomechanical effect on repaired rotator cuff muscle, especially after supplemented footprint repair. The purpose of this study was to assess the passive stiffness changes of the supraspinatus (SSP muscle after MC techniques using shear wave elastography (SWE. A 30 × 40-mm U-shaped rotator cuff tear was created in 8 cadaveric shoulders. Each specimen was repaired with 6 types of MC technique (1-, 2-, 3-suture MC with/without footprint repair, in a random order at 30° glenohumeral abduction. Passive stiffness of four anatomical regions in the SSP muscle was measured based on an established SWE method. Data were obtained from the SSP muscle at 0° abduction under 8 different conditions: intact (before making a tear, torn, and postoperative conditions with 6 techniques. MC techniques using 1-, or 2-suture combined with footprint repair showed significantly higher stiffness values than the intact condition. Passive stiffness of the SSP muscle was highest after a 1-suture MC with footprint repair for all regions when compared among all repair procedures. There was no significant difference between the intact condition and a 3-suture MC with footprint repair. MC techniques with single stitch and subsequent footprint repair may have adverse effects on muscle properties and tensile loading on repair, increasing the risk of retear of repairs. Adding more MC stitches could reverse these adverse effects.

Optimal Patient Positioning (Prone Versus Supine) for VMAT in Gynecologic Cancer: A Dosimetric Study on the Effect of Different Margins

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Heijkoop, Sabrina T., E-mail: s.heijkoop@erasmusmc.nl [Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam (Netherlands); Westerveld, Henrike; Bijker, Nina [Department of Radiation Oncology, Academic Medical Center, Amsterdam (Netherlands); Feije, Raphael; Sharfo, Abdul W. [Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam (Netherlands); Wieringen, Niek van [Department of Radiation Oncology, Academic Medical Center, Amsterdam (Netherlands); Mens, Jan Willem M. [Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam (Netherlands); Stalpers, Lukas J.A. [Department of Radiation Oncology, Academic Medical Center, Amsterdam (Netherlands); Hoogeman, Mischa S. [Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam (Netherlands)

2016-10-01

Purpose/Objective: It is unknown whether the historically found dosimetric advantages of treating gynecologic cancer with the patient in a prone position with use of a small-bowel displacement device (belly-board) remain when volumetric arc therapy (VMAT) is used and whether these advantages depend on the necessary margin between clinical target volume (CTV) and planning target volume (PTV). The aim of this study is to determine the best patient position (prone or supine) in terms of sparing organs at risk (OAR) for various CTV-to-PTV margins and VMAT dose delivery. Methods and Materials: In an institutional review board—approved study, 26 patients with gynecologic cancer scheduled for primary (9) or postoperative (17) radiation therapy were scanned in a prone position on a belly-board and in a supine position on the same day. The primary tumor CTV, nodal CTV, bladder, bowel, and rectum were delineated on both scans. The PTVs were created each with a different margin for the primary tumor and nodal CTV. The VMAT plans were generated with our in-house system for automated treatment planning. For all margin combinations, the supine and prone plans were compared with consideration of all OAR dose-volume parameters but with highest priority given to bowel cavity V{sub 45Gy} (cm{sup 3}). Results: For both groups, the prone position reduced the bowel cavity V{sub 45Gy}, in particular for nodal margins ≥10 mm (ΔV{sub 45Gy} = 23.9 ± 10.6 cm{sup 3}). However, for smaller margins, the advantage was much less pronounced (ΔV{sub 45Gy} = 6.5 ± 3.0 cm{sup 3}) and did not reach statistical significance. The rectum mean dose (D{sub mean}) was significantly lower (ΔD{sub mean} = 2.5 ± 0.3 Gy) in the prone position for both patient groups and for all margins, and the bladder D{sub mean} was significantly lower in the supine position (ΔD{sub mean} = 2.6 ± 0.4 Gy) only for the postoperative group. The advantage of the prone position was not present if it

Daily Online Cone Beam Computed Tomography to Assess Interfractional Motion in Patients With Intact Cervical Cancer

International Nuclear Information System (INIS)

Tyagi, Neelam; Lewis, John H.; Yashar, Catheryn M.; Vo, Daniel; Jiang, Steve B.; Mundt, Arno J.; Mell, Loren K.

2011-01-01

Purpose: To quantify interfraction motion in patients with intact cervical cancer and assess implications for clinical target volume (CTV) coverage and required planning margins. Methods and Materials: We analyzed 10 patients undergoing external beam radiotherapy using online cone beam computed tomography (CBCT) before each fraction. CTVs were contoured on the planning CT and on each CBCT. Each CBCT was rigidly registered to the planning CT with respect to bony anatomy. The CTV from each CBCT was projected onto the planning CT and compared to the CTV from the planning CT. Uniform three-dimensional expansions were applied to the planning CTV to assess required planning margins. For each fraction, the minimum margin required to encompass the CTV was calculated, and the volume of CTV (on the CBCT) encompassed by the PTV was determined as a function of margin size. Results: A uniform CTV planning treatment volume margin of 15 mm would have failed to encompass the CTV in 32% of fractions. The mean volume of CTV missed, however, was small (4 cc). The mean planning margin (across patients and fractions) required to encompass the CTV was 15 mm. Variation in margin estimates was high, with interpatient variation being the predominant component. Increased rectal volume was associated with posterior (p < 0.0001) and superior (p = 0.0004) shifts in the CTV, whereas increased bladder volume was associated with superior shifts (p < 0.0001). Conclusions: Interfraction motion results in a high probability of missing the CTV using conventional planning margins, but the volume of CTV missed is small. Adaptive radiotherapy approaches are needed to improve treatment accuracy.

Account for uncertainties of control measurements in the assessment of design margin factors

International Nuclear Information System (INIS)

Dementiev, V. G.; Sidorenko, V. D.; Shishkov, L. K.

2011-01-01

The paper discusses the feasibility of accounting for uncertainties of control measurements in estimation of design margin factors. The feasibility is also taken into consideration proceeding from the fact how much the processed measured data were corrected by a priori calculated data of measurable parameters. The possibility and feasibility of such data correction is demonstrated by the authors with the help of Bayes theorem famous in mathematical statistics. (Authors)

[Planning of esthetic oral rehabilitation according to correlative analysis of clinical and morphological features of the marginal gingiva].

Science.gov (United States)

Stafeev, A A; Zinov'ev, G I; Drozdov, D D

2015-01-01

The orthopedic restoration and related to its clinical stages (preparation, gingival retraction, impression) is often associated with complications which arise from the marginal gingiva. The technology of indirect ceramic restoration requires an assessment of the clinical and morphological parameters of periodontal tissues. The study outlines correlation between the type of periodontal histhology and inflammatory and degenerative complications that has been established after the analysis of morphofunctional state of periodontal tissue. Results of clinical studies and correlation analysis of clinical and morphological parameters of marginal gingiva has shown that important parameter influencing the choice of manufacturing technology are the position of restoration margin relatively to marginal gingiva and periodontal morphotype.

Erosion and marginalization in Pahuatlán municipality, Puebla: A binomial of causality?

Directory of Open Access Journals (Sweden)

Rosalía Castelán Vega

2012-02-01

Full Text Available An understanding of the interaction between deterioration of the environment and marginalization of communities is essential in order to formulate public policies that will combine social and environmental objectives. The aim of the present study was to explore the relationship between erosion and marginalization in the municipality of Pahuatlán, Puebla, Mexico. The erosion was assessed by the methods developed by FAO and Ruiz et al. Marginalization was determined by the Consejo Nacional de Población (CONAPO method using Instituto Nacional de Estadística, Geografía e Informática (INEGI indicators. The relationship was established by a simple correspondence analysis and was confirmed by Pearson´s Chi-square test. Erosion could be assigned to one of three grades: moderate, severe and very severe. In the 32 towns that constitute the municipality, marginalization was moderate in 5, severe in 14 and very severe in 13. The correspondence analysis and the Chi-square test showed a causal relationship between erosion and marginalization, although it was not possible to detect with certainty which is the cause and which the effect. However, the results can contribute to the design of sustainable strategies for the municipality.

Implications of power uprates on safety margins of nuclear power plants. Report of a technical meeting

International Nuclear Information System (INIS)

2004-09-01

The safety of nuclear power plants (NPPs) is based on the defence in depth concept, which relies on successive physical barriers (fuel matrix, cladding, primary system pressure boundary and containment) and other provisions to control radioactive materials and on multiple levels of protection against damage to these barriers. Deterministic safety analysis is an important tool for conforming the adequacy and efficiency of provisions within the defence in depth concept and is used to predict the response of an NPP in predetermined operational states. This type of safety analysis applies a specific set of rules and specific acceptance criteria. Deterministic analysis is typically focused on neutronic, thermohydraulic, radiological and structural aspects, which are often analysed with different computational tools. The advanced computational tools developed for deterministic safety analysis are used for better establishment and utilization of licensing margins or safety margins in consideration of analysis results. At the same time, the existence of such margins ensures that NPPs operate safely in all modes of operation and at all times. To properly assess and address the existing margins and to be able to take advantage of unnecessary conservatisms, state of the art analytical tools intended for safety assessment have been developed. Progress made in the development and application of modern codes for safety analysis and better understanding of phenomena involved in plant design and operation enable the analysts to determine safety margins in consideration of analysis results (licensing margins) with higher precision. There is a general tendency for utilities to take advantage of unnecessarily large conservatisms in safety analyses and to utilize them for reactor power uprates, better utilization of nuclear fuel, higher operational flexibility and for justification of lifetime extension. The present publication sets forth the results of a Technical Meeting on the

Risk insights from seismic margin reviews

International Nuclear Information System (INIS)

Budnitz, R.J.

1990-01-01

This paper discusses the information that has been derived from the three seismic-margin reviews conducted so far, and the information that is potentially available from using the seismic-margin method more generally. There are two different methodologies for conducting seismic margin reviews of nuclear power plants, one developed under NRC sponsorship and one developed under sponsorship of the Electric Power Research Institute. Both methodologies will be covered in this paper. The paper begins with a summary of the steps necessary to complete a margin review, and will then outline the key technical difficulties that need to be addressed. After this introduction, the paper covers the safety and operational insights derived from the three seismic-margin reviews already completed: the NRC-sponsored review at Maine Yankee; the EPRI-sponsored review at Catawba; and the joint EPRI/NRC/utility effort at Hatch. The emphasis is on engineering insights, with attention to the aspects of the reviews that are easiest to perform and that provide the most readily available insights

Targeting incentives to reduce habitat fragmentation

Science.gov (United States)

David Lewis; Andrew Plantinga; Junjie Wu

2009-01-01

This article develops a theoretical model to analyze the spatial targeting of incentives for the restoration of forested landscapes when wildlife habitat can be enhanced by reducing fragmentation. The key theoretical result is that the marginal net benefits of increasing forest can be convex, in which case corner solutions--converting either none or all of the...

Exactly marginal deformations from exceptional generalised geometry

Energy Technology Data Exchange (ETDEWEB)

Ashmore, Anthony [Merton College, University of Oxford,Merton Street, Oxford, OX1 4JD (United Kingdom); Mathematical Institute, University of Oxford,Andrew Wiles Building, Woodstock Road, Oxford, OX2 6GG (United Kingdom); Gabella, Maxime [Institute for Advanced Study,Einstein Drive, Princeton, NJ 08540 (United States); Graña, Mariana [Institut de Physique Théorique, CEA/Saclay,91191 Gif-sur-Yvette (France); Petrini, Michela [Sorbonne Université, UPMC Paris 05, UMR 7589, LPTHE,75005 Paris (France); Waldram, Daniel [Department of Physics, Imperial College London,Prince Consort Road, London, SW7 2AZ (United Kingdom)

2017-01-27

We apply exceptional generalised geometry to the study of exactly marginal deformations of N=1 SCFTs that are dual to generic AdS{sub 5} flux backgrounds in type IIB or eleven-dimensional supergravity. In the gauge theory, marginal deformations are parametrised by the space of chiral primary operators of conformal dimension three, while exactly marginal deformations correspond to quotienting this space by the complexified global symmetry group. We show how the supergravity analysis gives a geometric interpretation of the gauge theory results. The marginal deformations arise from deformations of generalised structures that solve moment maps for the generalised diffeomorphism group and have the correct charge under the generalised Reeb vector, generating the R-symmetry. If this is the only symmetry of the background, all marginal deformations are exactly marginal. If the background possesses extra isometries, there are obstructions that come from fixed points of the moment maps. The exactly marginal deformations are then given by a further quotient by these extra isometries. Our analysis holds for any N=2 AdS{sub 5} flux background. Focussing on the particular case of type IIB Sasaki-Einstein backgrounds we recover the result that marginal deformations correspond to perturbing the solution by three-form flux at first order. In various explicit examples, we show that our expression for the three-form flux matches those in the literature and the obstruction conditions match the one-loop beta functions of the dual SCFT.

Clearing margin system in the futures markets—Applying the value-at-risk model to Taiwanese data

Science.gov (United States)

Chiu, Chien-Liang; Chiang, Shu-Mei; Hung, Jui-Cheng; Chen, Yu-Lung

2006-07-01

This article sets out to investigate if the TAIFEX has adequate clearing margin adjustment system via unconditional coverage, conditional coverage test and mean relative scaled bias to assess the performance of three value-at-risk (VaR) models (i.e., the TAIFEX, RiskMetrics and GARCH-t). For the same model, original and absolute returns are compared to explore which can accurately capture the true risk. For the same return, daily and tiered adjustment methods are examined to evaluate which corresponds to risk best. The results indicate that the clearing margin adjustment of the TAIFEX cannot reflect true risks. The adjustment rules, including the use of absolute return and tiered adjustment of the clearing margin, have distorted VaR-based margin requirements. Besides, the results suggest that the TAIFEX should use original return to compute VaR and daily adjustment system to set clearing margin. This approach would improve the funds operation efficiency and the liquidity of the futures markets.

Observations at convergent margins concerning sediment subduction, subduction erosion, and the growth of continental crust

Science.gov (United States)

von Huene, Roland E.; Scholl, D. W.

1991-01-01

subducted beneath the frontal accretionary body and its active buttress. In rounded figures the contemporary rate of solid-volume sediment subduction at convergent ocean margins (???43,500 km) is calculated to be 1.5 km3/yr. Correcting type 1 margins for high rates of terrigenous seafloor sedimentation during the past 30 m.y. or so sets the long-term rate of sediment subduction at 1.0 km3/yr. The bulk of the subducted material is derived directly or indirectly from continental denudation. Interstitial water currently expulsed from accreted and deeply subducted sediment and recycled to the ocean basins is estimated at 0.9 km3/yr. The thinning and truncation caused by subduction erosion of the margin's framework rock and overlying sedimentary deposits have been demonstrated at many convergent margins but only off northern Japan, central Peru, and northern Chile has sufficient information been collected to determine average or long-term rates, which range from 25 to 50 km3/m.y. per kilometer of margin. A conservative long-term rate applicable to many sectors of convergent margins is 30 km3/km/m.y. If applied to the length of type 2 margins, subduction erosion removes and transports approximately 0.6 km3/yr of upper plate material to greater depths. At various places, subduction erosion also affects sectors of type 1 margins bordered by small- to medium-sized accretionary prisms (for example, Japan and Peru), thus increasing the global rate by possibly 0.5 km3/yr to a total of 1.1 km3/yr. Little information is available to assess subduction erosion at margins bordered by large accretionary prisms. Mass balance calculations allow assessments to be made of the amount of subducted sediment that bypasses the prism and underthrusts the margin's rock framework. This subcrustally subducted sediment is estimated at 0.7 km3/yr. Combined with the range of terrestrial matter removed from the margin's rock framework by subduction erosion, the global volume of subcrustally subducted materia

RISK-INFORMED SAFETY MARGIN CHARACTERIZATION

International Nuclear Information System (INIS)

Dinh, Nam; Szilard, Ronaldo

2009-01-01

The concept of safety margins has served as a fundamental principle in the design and operation of commercial nuclear power plants (NPPs). Defined as the minimum distance between a system's 'loading' and its 'capacity', plant design and operation is predicated on ensuring an adequate safety margin for safety-significant parameters (e.g., fuel cladding temperature, containment pressure, etc.) is provided over the spectrum of anticipated plant operating, transient and accident conditions. To meet the anticipated challenges associated with extending the operational lifetimes of the current fleet of operating NPPs, the United States Department of Energy (USDOE), the Idaho National Laboratory (INL) and the Electric Power Research Institute (EPRI) have developed a collaboration to conduct coordinated research to identify and address the technological challenges and opportunities that likely would affect the safe and economic operation of the existing NPP fleet over the postulated long-term time horizons. In this paper we describe a framework for developing and implementing a Risk-Informed Safety Margin Characterization (RISMC) approach to evaluate and manage changes in plant safety margins over long time horizons

Pathologic margin involvement and the risk of recurrence in patients treated with breast-conserving therapy

International Nuclear Information System (INIS)

Gage, Irene; Nixon, Asa J.; Schnitt, Stuart J.; Recht, Abram; Gelman, Rebecca; Silver, Barbara; Connolly, James L.; Harris, Jay R.

1995-01-01

PURPOSE: To assess the relationship between microscopic margin status and recurrence after breast-conserving therapy for tumors with or without an extensive intraductal component (EIC). MATERIALS AND METHODS: During the years 1968 to 1986, 1865 women with unilateral clinical stage I or II breast cancer were treated with radiation therapy for breast conservation. Of these, 340 received ≥60 Gy to the tumor bed and had margins that were evaluable on review of their pathologic slides; these constitute the study population. The median follow-up was 109 months. All available slides were reviewed by one of the study pathologists (SS, JC). Final radial margins of excision were classified as negative >1 mm (no invasive or ductal carcinoma in-situ within 1 mm of the inked margin), negative ≤1 mm (any carcinoma ≤1 mm of the inked margin but not at ink) or positive (any carcinoma at the inked margin). A focally positive margin was defined as any invasive or in-situ carcinoma at the margin in ≤3 LPF. The extent of positivity was not evaluable in 2 patients and the distance of the tumor from the margin was not evaluable in 48 patients with a negative margin. Thirty-nine percent of EIC-negative and 46% of EIC-positive patients underwent a re-excision and, for these, the final margin analyzed was from the re-excised specimen. The median dose to the tumor bed was 63 Gy for patients with positive margins and 62 Gy for patients with negative margins. Recurrent disease was classified as ipsilateral breast recurrence (IBR) or distant metastasis/regional nodal failure (DM/RNF). RESULTS: Five year crude rates for the first site of recurrence were calculated for 340 patients evaluable at 5 years. Results were tabulated separately for all patients, EIC-negative and EIC-positive. All p-values tested for differences in the distribution of sites of first failure. CONCLUSIONS: The risk of ipsilateral breast recurrence is equally low for patients with close (≤1 mm) or negative (>1 mm

A phase-I trial of pre‐operative, margin intensive, stereotactic body radiation therapy for pancreatic cancer: the ‘SPARC’ trial protocol

International Nuclear Information System (INIS)

Holyoake, Daniel L. P.; Ward, Elizabeth; Grose, Derek; McIntosh, David; Sebag-Montefiore, David; Radhakrishna, Ganesh; Patel, Neel; Silva, Michael; Mukherjee, Somnath; Strauss, Victoria Y.; Odondi, Lang’o; Fokas, Emmanouil; Melcher, Alan; Hawkins, Maria A.

2016-01-01

Standard therapy for borderline-resectable pancreatic cancer in the UK is surgery with adjuvant chemotherapy, but rates of resection with clear margins are unsatisfactory and overall survival remains poor. Meta-analysis of single-arm studies shows the potential of neo-adjuvant chemo-radiotherapy but the relative radio-resistance of pancreatic cancer means the efficacy of conventional dose schedules is limited. Stereotactic radiotherapy achieves sufficient accuracy and precision to enable pre-operative margin-intensive dose escalation with the goal of increasing rates of clear resection margins and local disease control. SPARC is a “rolling-six” design single-arm study to establish the maximum tolerated dose for margin-intensive stereotactic radiotherapy before resection of pancreatic cancer at high risk of positive resection margins. Eligible patients will have histologically or cytologically proven pancreatic cancer defined as borderline-resectable per National Comprehensive Cancer Network criteria or operable tumour in contact with vessels increasing the risk of positive margin. Up to 24 patients will be recruited from up to 5 treating centres and a ‘rolling-six’ design is utilised to minimise delays and facilitate ongoing recruitment during dose-escalation. Radiotherapy will be delivered in 5 daily fractions and surgery, if appropriate, will take place 5–6 weeks after radiotherapy. The margin-intense radiotherapy concept includes a systematic method to define the target volume for a simultaneous integrated boost in the region of tumour-vessel infiltration, and up to 4 radiotherapy dose levels will be investigated. Maximum tolerated dose is defined as the highest dose at which no more than 1 of 6 patients or 0 of 3 patients experience a dose limiting toxicity. Secondary endpoints include resection rate, resection margin status, response rate, overall survival and progression free survival at 12 and 24 months. Translational work will involve exploratory

Targets for global climate policy : An overview

NARCIS (Netherlands)

Tol, Richard S.J.

A survey of the economic impact of climate change and the marginal damage costs shows that carbon dioxide emissions are a negative externality. The estimated Pigou tax and its growth rate are too low to justify the climate policy targets set by political leaders. A lower discount rate or greater

Marginal Cost Pricing in a World without Perfect Competition: Implications for Electricity Markets with High Shares of Low Marginal Cost Resources

Energy Technology Data Exchange (ETDEWEB)

Frew, Bethany A. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Clark, Kara [National Renewable Energy Lab. (NREL), Golden, CO (United States); Bloom, Aaron P. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Milligan, Michael [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2017-12-02

A common approach to regulating electricity is through auction-based competitive wholesale markets. The goal of this approach is to provide a reliable supply of power at the lowest reasonable cost to the consumer. This necessitates market structures and operating rules that ensure revenue sufficiency for all generators needed for resource adequacy purposes. Wholesale electricity markets employ marginal-cost pricing to provide cost-effective dispatch such that resources are compensated for their operational costs. However, marginal-cost pricing alone cannot guarantee cost recovery outside of perfect competition, and electricity markets have at least six attributes that preclude them from functioning as perfectly competitive markets. These attributes include market power, externalities, public good attributes, lack of storage, wholesale price caps, and ineffective demand curve. Until (and unless) these failures are ameliorated, some form of corrective action(s) will be necessary to improve market efficiency so that prices can correctly reflect the needed level of system reliability. Many of these options necessarily involve some form of administrative or out-of-market actions, such as scarcity pricing, capacity payments, bilateral or other out-of-market contracts, or some hybrid combination. A key focus with these options is to create a connection between the electricity market and long-term reliability/loss-of-load expectation targets, which are inherently disconnected in the native markets because of the aforementioned market failures. The addition of variable generation resources can exacerbate revenue sufficiency and resource adequacy concerns caused by these underlying market failures. Because variable generation resources have near-zero marginal costs, they effectively suppress energy prices and reduce the capacity factors of conventional generators through the merit-order effect in the simplest case of a convex market; non-convexities can also suppress prices.

Multiple Maneuvering Target Tracking by Improved Particle Filter Based on Multiscan JPDA

Directory of Open Access Journals (Sweden)

Jing Liu

2012-01-01

Full Text Available The multiple maneuvering target tracking algorithm based on a particle filter is addressed. The equivalent-noise approach is adopted, which uses a simple dynamic model consisting of target state and equivalent noise which accounts for the combined effects of the process noise and maneuvers. The equivalent-noise approach converts the problem of maneuvering target tracking to that of state estimation in the presence of nonstationary process noise with unknown statistics. A novel method for identifying the nonstationary process noise is proposed in the particle filter framework. Furthermore, a particle filter based multiscan Joint Probability Data Association (JPDA filter is proposed to deal with the data association problem in a multiple maneuvering target tracking. In the proposed multiscan JPDA algorithm, the distributions of interest are the marginal filtering distributions for each of the targets, and these distributions are approximated with particles. The multiscan JPDA algorithm examines the joint association events in a multiscan sliding window and calculates the marginal posterior probability based on the multiscan joint association events. The proposed algorithm is illustrated via an example involving the tracking of two highly maneuvering, at times closely spaced and crossed, targets, based on resolved measurements.

Professional Commitment and Professional Marginalism in Teachers

Directory of Open Access Journals (Sweden)

Kalashnikov A.I.

2017-11-01

Full Text Available The article reviews teachers' attitudes towards the teaching profession which can be expressed both in professional commitment and in professional marginalism. The dominance of professional marginalism could affect destructively the students as well as the teacher’s personality, hence the issues related to the content of personal position of a marginal and the rate of marginalism among teachers. It was suggested that marginalism could be revealed in the study of professional commitment. The study involved 81 teachers of Sverdlovsk secondary schools aged 21—60 years with work experience ranging from 1 month to 39 years. The Professional Commitment Questionnaire was used as the study technique. The results showed that negative emotional attitude towards the profession and reluctance to leave the profession were grouped as a separate factor. The dispersion factor was 12,5%. The factor loadings ranged from 0.42 to 0.84. The study proved that professional marginalism in teachers includes dissatisfaction with work, feelings of resentment against profession and an unwillingness to leave the profession.

A quantitative analysis of transtensional margin width

Science.gov (United States)

Jeanniot, Ludovic; Buiter, Susanne J. H.

2018-06-01

Continental rifted margins show variations between a few hundred to almost a thousand kilometres in their conjugated widths from the relatively undisturbed continent to the oceanic crust. Analogue and numerical modelling results suggest that the conjugated width of rifted margins may have a relationship to their obliquity of divergence, with narrower margins occurring for higher obliquity. We here test this prediction by analysing the obliquity and rift width for 26 segments of transtensional conjugate rifted margins in the Atlantic and Indian Oceans. We use the plate reconstruction software GPlates (http://www.gplates.org) for different plate rotation models to estimate the direction and magnitude of rifting from the initial phases of continental rifting until breakup. Our rift width corresponds to the distance between the onshore maximum topography and the last identified continental crust. We find a weak positive correlation between the obliquity of rifting and rift width. Highly oblique margins are narrower than orthogonal margins, as expected from analogue and numerical models. We find no relationships between rift obliquities and rift duration nor the presence or absence of Large Igneous Provinces (LIPs).

Using a Marginal Structural Model to Design a Theory-Based Mass Media Campaign.

Directory of Open Access Journals (Sweden)

Hiromu Nishiuchi

Full Text Available The essential first step in the development of mass media health campaigns is to identify specific beliefs of the target audience. The challenge is to prioritize suitable beliefs derived from behavioral theory. The purpose of this study was to identify suitable beliefs to target in a mass media campaign to change behavior using a new method to estimate the possible effect size of a small set of beliefs.Data were drawn from the 2010 Japanese Young Female Smoker Survey (n = 500, conducted by the Japanese Ministry of Health, Labor and Welfare. Survey measures included intention to quit smoking, psychological beliefs (attitude, norms, and perceived control based on the theory of planned behavior and socioeconomic status (age, education, household income, and marital status. To identify suitable candidate beliefs for a mass media health campaign, we estimated the possible effect size required to change the intention to quit smoking among the population of young Japanese women using the population attributable fraction from a marginal structural model.Thirteen percent of study participants intended to quit smoking. The marginal structural model estimated a population attributable fraction of 47 psychological beliefs (21 attitudes, 6 norms, and 19 perceived controls after controlling for socioeconomic status. The belief, "I could quit smoking if my husband or significant other recommended it" suggested a promising target for a mass media campaign (population attributable fraction = 0.12, 95% CI = 0.02-0.23. Messages targeting this belief could possibly improve intention rates by up to 12% among this population. The analysis also suggested the potential for regulatory action.This study proposed a method by which campaign planners can develop theory-based mass communication strategies to change health behaviors at the population level. This method might contribute to improving the quality of future mass health communication strategies and further

Using a Marginal Structural Model to Design a Theory-Based Mass Media Campaign.

Science.gov (United States)

Nishiuchi, Hiromu; Taguri, Masataka; Ishikawa, Yoshiki

2016-01-01

The essential first step in the development of mass media health campaigns is to identify specific beliefs of the target audience. The challenge is to prioritize suitable beliefs derived from behavioral theory. The purpose of this study was to identify suitable beliefs to target in a mass media campaign to change behavior using a new method to estimate the possible effect size of a small set of beliefs. Data were drawn from the 2010 Japanese Young Female Smoker Survey (n = 500), conducted by the Japanese Ministry of Health, Labor and Welfare. Survey measures included intention to quit smoking, psychological beliefs (attitude, norms, and perceived control) based on the theory of planned behavior and socioeconomic status (age, education, household income, and marital status). To identify suitable candidate beliefs for a mass media health campaign, we estimated the possible effect size required to change the intention to quit smoking among the population of young Japanese women using the population attributable fraction from a marginal structural model. Thirteen percent of study participants intended to quit smoking. The marginal structural model estimated a population attributable fraction of 47 psychological beliefs (21 attitudes, 6 norms, and 19 perceived controls) after controlling for socioeconomic status. The belief, "I could quit smoking if my husband or significant other recommended it" suggested a promising target for a mass media campaign (population attributable fraction = 0.12, 95% CI = 0.02-0.23). Messages targeting this belief could possibly improve intention rates by up to 12% among this population. The analysis also suggested the potential for regulatory action. This study proposed a method by which campaign planners can develop theory-based mass communication strategies to change health behaviors at the population level. This method might contribute to improving the quality of future mass health communication strategies and further research is needed.

Marginal overweight operating scenario for DOE's initiative I highway casks

International Nuclear Information System (INIS)

Hill, C.V.; Loud, G.C.; Heitzman, A.C.

1993-01-01

This paper assesses the potential transport of high-capacity Initiative I highway casks under development by the Office of Civilian Radioactive Waste Management (OCRWM) as permitted marginal overweight shipments that: exceed a gross vehicle weight (gvw) limit of 80,000, but weight less than 96,000 pounds; follow axle and axle group weight limits adopted by the Surface Transportation Assistance Act (STAA) of 1982; conform to dimensional restrictions to operate on most major highways; and comply with the Federal Bridge Formula. The marginal overweight tractor-trailer would operate in normal open-quotes over-the-roadclose quotes mode and comply with all laws and regulations. The vehicle would have a sleeper berth and two drivers - one to drive while the other provides escort and communications services and accumulates required off-duty time

Comparison of 2D and 3D algorithms for adding a margin to the gross tumor volume in the conformal radiotherapy planning of prostate cancer

International Nuclear Information System (INIS)

Khoo, Vincent S.; Bedford, James L.; Webb, Steve; Dearnaley, David P.

1998-01-01

Purpose: To evaluate the adequacy of tumor volume coverage using a three-dimensional (3D) margin-growing algorithm compared to a two-dimensional (2D) margin-growing algorithm in the conformal radiotherapy planning of prostate cancer. Methods and Materials: Two gross tumor volumes (GTV) were segmented in each of 10 patients with localized prostate cancer; prostate gland only (PO) and prostate with seminal vesicles (PSV). A predetermined margin of 10 mm was applied to these two groups (PO and PSV) using both 2D and 3D margin-growing algorithms. The 2D algorithm added a transaxial margin to each GTV slice, whereas the 3D algorithm added a volumetric margin all around the GTV. The true planning target volume (PTV) was defined as the region delineated by the 3D algorithm. The adequacy of geometric coverage of the GTV by the two algorithms was examined in a series of transaxial planes throughout the target volume. Results: The 2D margin-growing algorithm underestimated the PTV by 17% (range 12-20) in the PO group and by 20% (range 13-28) for the PSV group when compared to the 3D-margin algorithm. For the PO group, the mean transaxial difference between the 2D and 3D algorithm was 3.8 mm inferiorly (range 0-20), 1.8 mm centrally (range 0-9), and 4.4 mm superiorly (range 0-22). Considering all of these regions, the mean discrepancy anteriorly was 5.1 mm (range 0-22), posteriorly 2.2 (range 0-20), right border 2.8 mm (range 0-14), and left border 3.1 mm (range 0-12). For the PSV group, the mean discrepancy in the inferior region was 3.8 mm (range 0-20), central region of the prostate was 1.8 mm ( range 0-9), the junction region of the prostate and the seminal vesicles was 5.5 mm (range 0-30), and the superior region of the seminal vesicles was 4.2 mm (range 0-55). When the different borders were considered in the PSV group, the mean discrepancies for the anterior, posterior, right, and left borders were 6.4 mm (range 0-55), 2.5 mm (range 0-20), 2.6 mm (range 0-14), and 3

On the evaluation of marginal expected shortfall

DEFF Research Database (Denmark)

Caporin, Massimiliano; Santucci de Magistris, Paolo

2012-01-01

In the analysis of systemic risk, Marginal Expected Shortfall may be considered to evaluate the marginal impact of a single stock on the market Expected Shortfall. These quantities are generally computed using log-returns, in particular when there is also a focus on returns conditional distribution....... In this case, the market log-return is only approximately equal to the weighed sum of equities log-returns. We show that the approximation error is large during turbulent market phases, with a subsequent impact on Marginal Expected Shortfall. We then suggest how to improve the evaluation of Marginal Expected...

[Resection margins in conservative breast cancer surgery].

Science.gov (United States)

Medina Fernández, Francisco Javier; Ayllón Terán, María Dolores; Lombardo Galera, María Sagrario; Rioja Torres, Pilar; Bascuñana Estudillo, Guillermo; Rufián Peña, Sebastián

2013-01-01

Conservative breast cancer surgery is facing a new problem: the potential tumour involvement of resection margins. This eventuality has been closely and negatively associated with disease-free survival. Various factors may influence the likelihood of margins being affected, mostly related to the characteristics of the tumour, patient or surgical technique. In the last decade, many studies have attempted to find predictive factors for margin involvement. However, it is currently the new techniques used in the study of margins and tumour localisation that are significantly reducing reoperations in conservative breast cancer surgery. Copyright © 2012 AEC. Published by Elsevier Espana. All rights reserved.

Label-free optical imaging technologies for rapid translation and use during intraoperative surgical and tumor margin assessment

Science.gov (United States)

Boppart, Stephen A.; Brown, J. Quincy; Farah, Camile S.; Kho, Esther; Marcu, Laura; Saunders, Christobel M.; Sterenborg, Henricus J. C. M.

2018-02-01

The biannual International Conference on Biophotonics was recently held on April 30 to May 1, 2017, in Fremantle, Western Australia. This continuing conference series brought together key opinion leaders in biophotonics to present their latest results and, importantly, to participate in discussions on the future of the field and what opportunities exist when we collectively work together for using biophotonics for biological discovery and medical applications. One session in this conference, entitled "Tumor Margin Identification: Critiquing Technologies," challenged invited speakers and attendees to review and critique representative label-free optical imaging technologies and their application for intraoperative assessment and guidance in surgical oncology. We are pleased to share a summary in this outlook paper, with the intent to motivate more research inquiry and investigations, to challenge these and other optical imaging modalities to evaluate and improve performance, to spur translation and adoption, and ultimately, to improve the care and outcomes of patients.

Ferritin associates with marginal band microtubules

International Nuclear Information System (INIS)

Infante, Anthony A.; Infante, Dzintra; Chan, M.-C.; How, P.-C.; Kutschera, Waltraud; Linhartova, Irena; Muellner, Ernst W.; Wiche, Gerhard; Propst, Friedrich

2007-01-01

We characterized chicken erythrocyte and human platelet ferritin by biochemical studies and immunofluorescence. Erythrocyte ferritin was found to be a homopolymer of H-ferritin subunits, resistant to proteinase K digestion, heat stable, and contained iron. In mature chicken erythrocytes and human platelets, ferritin was localized at the marginal band, a ring-shaped peripheral microtubule bundle, and displayed properties of bona fide microtubule-associated proteins such as tau. Red blood cell ferritin association with the marginal band was confirmed by temperature-induced disassembly-reassembly of microtubules. During erythrocyte differentiation, ferritin co-localized with coalescing microtubules during marginal band formation. In addition, ferritin was found in the nuclei of mature erythrocytes, but was not detectable in those of bone marrow erythrocyte precursors. These results suggest that ferritin has a function in marginal band formation and possibly in protection of the marginal band from damaging effects of reactive oxygen species by sequestering iron in the mature erythrocyte. Moreover, our data suggest that ferritin and syncolin, a previously identified erythrocyte microtubule-associated protein, are identical. Nuclear ferritin might contribute to transcriptional silencing or, alternatively, constitute a ferritin reservoir

Limitations of ''margin'' in qualification tests

International Nuclear Information System (INIS)

Clough, R.L.; Gillen, K.T.

1984-01-01

We have carried out investigations of polymer radiation degradation behaviors which have brought to light a number of reasons why this concept of margin can break down. First of all, we have found that dose-rate effects vary greatly in magnitude. Thus, based on high dose-rate testing, poor materials with large dose-rate effects may be selected over better materials with small effects. Also, in certain cases, material properties have been found to level out (as with PVC) or reverse trend (as with buna-n) at high doses, so that ''margin'' may be ineffective, misleading, or counterproductive. For Viton, the material properties were found to change in opposite directions at high and low dose rates, making ''margin'' inappropriate. The underlying problem with the concept of ''margin'' is that differences in aging conditions can lead to fundamental differences in degradation mechanisms

Silenced, Silence, Silent: Motherhood in the Margins

Science.gov (United States)

Carpenter, Lorelei; Austin, Helena

2007-01-01

This project explores the experiences of women who mother children with ADHD. The authors use the metaphor of the text and the margin. The text is the "motherhood myth" that describes a particular sort of "good" mothering. The margin is the space beyond that text. This marginal space is inhabited by some or all of the mothers they spoke with, some…

Seismic margins and calibration of piping systems

International Nuclear Information System (INIS)

Shieh, L.C.; Tsai, N.C.; Yang, M.S.; Wong, W.L.

1985-01-01

The Seismic Safety Margins Research Program (SSMRP) is a US Nuclear Regulatory Commission-funded, multiyear program conducted by Lawrence Livermore National Laboratory (LLNL). Its objective is to develop a complete, fully coupled analysis procedure for estimating the risk of earthquake-induced radioactive release from a commercial nuclear power plant and to determine major contributors to the state-of-the-art seismic and systems analysis process and explicitly includes the uncertainties in such a process. The results will be used to improve seismic licensing requirements for nuclear power plants. In Phase I of SSMRP, the overall seismic risk assessment methodology was developed and assembled. The application of this methodology to the seismic PRA (Probabilistic Risk Assessment) at the Zion Nuclear Power Plant has been documented. This report documents the method deriving response factors. The response factors, which relate design calculated responses to best estimate values, were used in the seismic response determination of piping systems for a simplified seismic probablistic risk assessment. 13 references, 31 figures, 25 tables

Assessment of margins with respect to pressurized thermal shock for the 3 loop plants of the French program

International Nuclear Information System (INIS)

Buchalet, C.; Haussaire, P.; Houssin, B.; Vagner, J.

1983-08-01

Presentation of the FRAMATOME and EDF program on pressurized thermal shock which objectives are to demonstrate that present and older French reactor vessels have adequate safety margins and to provide recommendations of feasible plant specific modifications, both technically and economically. Phase I consists in a thorough analysis of pressure and temperature transients that the R.P.V. beltine could undergo during plant operations; phase II is the fracture mechanics analysis; phase III estimates the safety margins available during normal, upset, emergency and faulted conditions

Effect of MLC Leaf Width and PTV Margin on the Treatment Planning of Intensity-Modulated Stereotactic Radiosurgery (IMSRS) or Radiotherapy (IMSRT)

International Nuclear Information System (INIS)

Chang Jenghwa; Yenice, Kamil M.; Jiang Kailiu; Hunt, Margie; Narayana, Ashwatha

2009-01-01

We studied the effect of MLC (multileaf collimator) leaf width and PTV (planning target volume) margin on treatment planning of intensity modulated stereotactic radiosurgery (IMSRS) or radiotherapy (IMSRT). Twelve patients previously treated with IMSRS/IMSRT were retrospectively planned with 5- and 3-mm MLC leaf widths and 3- and 2-mm PTV margins using the already contoured clinical target volume and critical structures. The same beam arrangement, planning parameters, and optimization method were used in each of the 4 plans for a given patient. Each plan was normalized so that the prescription dose covered at least 99% of the PTV. Plan indices - D mean (mean dose), conformity index (CI), V 70 (volume receiving ≥ 70% of the prescription dose), and V 50 (volume receiving ≥ 50% of the prescription dose) - were calculated from the dose-volume histograms (DVHs) of the PTV, normal tissue, and organs at risk (OARs). Hypothesis testing was performed on the mean ratios of plan indices to determine the statistical significance of the relative differences. The PTV was well covered for all plans, as no significant differences were observed for D 95 , V 95 , D max , D min , and D mean of the PTV. The irradiated volume was ∼23% smaller when 2-mm instead of 3-mm PTV margin was used, but it was only reduced by ∼6% when the MLC leaf width was reduced from 5 mm to 3 mm. For normal tissue and brainstem, V 70 , V 50 , and D mean were reduced more effectively by a decrease in MLC width, while D mean of optic nerve and chiasm were more sensitive to a change in PTV margin. The DVH statistics for the PTV and normal structures from the treatment plan with 5-mm MLC and 2-mm PTV margin were equal to those with 3-mm MLC and 3-mm PTV margin. PTV margin reduction is more effective in sparing the normal tissue and OARs than a reduction in MLC leaf width. For IMSRS, where highly accurate setup and small PTV margins are routinely employed, the use of 5-mm MLC is therefore less desirable.

Assessing the Response to Targeted Therapies in Renal Cell Carcinoma: Technical Insights and Practical Considerations

NARCIS (Netherlands)

Bex, A.; Fournier, L.; Lassau, N.; Mulders, P.F.A.; Nathan, P.; Oyen, W.J.G.; Powles, T.

2014-01-01

CONTEXT: The introduction of targeted agents for the treatment of renal cell carcinoma (RCC) has resulted in new challenges for assessing response to therapy, and conventional response criteria using computed tomography (CT) are limited. It is widely recognised that targeted therapies may lead to

Influence of margin status and radiation on recurrence after radical hysterectomy in Stage IB cervical cancer

International Nuclear Information System (INIS)

Viswanathan, Akila N.; Lee, Hang; Hanson, Emily; Berkowitz, Ross S.; Crum, Christopher P.

2006-01-01

Purpose: To examine the relationship between margin status and local recurrence (LR) or any recurrence after radical hysterectomy (RH) in women treated with or without radiotherapy (RT) for Stage IB cervical carcinoma. Methods and Materials: This study included 284 patients after RH with assessable margins between 1980 and 2000. Each margin was scored as negative (≥1 cm), close (>0 and <1 cm), or positive. The outcomes measured were any recurrence, LR, and relapse-free survival. Results: The crude rate for any recurrence was 11%, 20%, and 38% for patients with negative, close, and positive margins, respectively. The crude rate for LR was 10%, 11%, and 38%, respectively. Postoperative RT decreased the rate of LR from 10% to 0% for negative, 17% to 0% for close, and 50% to 25% for positive margins. The significant predictors of decreased relapse-free survival on univariate analysis were the depth of tumor invasion (hazard ratio [HR] 2.14/cm increase, p = 0.007), positive margins (HR 3.92, p = 0.02), tumor size (HR 1.3/cm increase, p = 0.02), lymphovascular invasion (HR 2.19, p = 0.03), and margin status (HR 0.002/increasing millimeter from cancer for those with close margins, p = 0.03). Long-term side effects occurred in 8% after RH and 19% after RH and RT. Conclusion: The use of postoperative RT may decrease the risk of LR in patients with close paracervical margins. Patients with other adverse prognostic factors and close margins may also benefit from the use of postoperative RT. However, RT after RH may increase the risk of long-term side effects

Assessment of Submarine Slope Stability on the Continental Margin off SW Taiwan

Science.gov (United States)

Hsu, Huai-Houh; Dong, Jia-Jyun; Cheng, Win-Bin; Su, Chih-Chieh

2017-04-01

The abundant gas hydrate reservoirs are distributed in the southwest (SW) off Taiwan. To explore this new energy, geological methods were systematically used and mainly emphasized on the storage potential evaluation. On the other hand, the correlation between gas hydrate dissociation and submarine slope stability is also an important issue. In this study, three submarine profiles on the active and passive continental margin were selected and assessed their slope stabilities by considering two influence factors (seismic forces and number of sedimentary layers). The gravity corers obtained from these three sites (Xiaoliuqiu, Yuan-An Ridge, and Pointer Ridge) to conduct soil laboratory tests. The physical property tests and isotropically consolidated undrained (CIU) triaxial tests were carried out to establish reference properties and shear strength parameters. Before the stability analysis is performed, it is also necessary to construct the seabed profile. For each submarine profile, data from P-waves and from S-waves generated by P-S conversion on reflection from airgun shots recorded along one line of ocean bottom seismometers were used to construct 2-D velocity sections. The seabed strata could be simplified to be only one sedimentary layer or to be multilayer in accordance with the velocity structure profile. Results show the safety factors (FS) of stability analysis are obviously different in considering the number of sedimentary layers, especially for a very thin layer of sediments on a steep slope. The simplified strata condition which treated all seabed strata as only one sedimentary layer might result in the FS lower than 1 and the slope was in an unstable state. On the contrary, the FS could be higher than 10 in a multilayer condition.

Aspects of marginal expenditures in energy sector

International Nuclear Information System (INIS)

Stojchev, D.; Kynev, K.

1994-01-01

Technical and economical problems of marginal analysis methodology, its application procedure in energy sector and marginal expenditures determination are outlined. A comparative characteristics of the application is made for different periods of time. The differences in calculation of the marginal expenditures and prices are discussed. The operational costs, investments and inflation are analyzed. The mechanism of application of this approach in different planing horizon is outlined. The role of the change in the costs in time, the time unit, volume, the scope of application, etc. are determined. The areas of transition from one to other form of marginal expenditures are shown. 4 refs. (orig.)

Characterizing entanglement with global and marginal entropic measures

International Nuclear Information System (INIS)

Adesso, Gerardo; Illuminati, Fabrizio; De Siena, Silvio

2003-01-01

We qualify the entanglement of arbitrary mixed states of bipartite quantum systems by comparing global and marginal mixednesses quantified by different entropic measures. For systems of two qubits we discriminate the class of maximally entangled states with fixed marginal mixednesses, and determine an analytical upper bound relating the entanglement of formation to the marginal linear entropies. This result partially generalizes to mixed states the quantification of entanglement with marginal mixednesses holding for pure states. We identify a class of entangled states that, for fixed marginals, are globally more mixed than product states when measured by the linear entropy. Such states cannot be discriminated by the majorization criterion

Steel Industry Marginal Opportunity Analysis

Energy Technology Data Exchange (ETDEWEB)

none,

2005-09-01

The Steel Industry Marginal Opportunity Analysis (PDF 347 KB) identifies opportunities for developing advanced technologies and estimates both the necessary funding and the potential payoff. This analysis determines what portion of the energy bandwidth can be captured through the adoption of state-of-the-art technology and practices. R&D opportunities for addressing the remainder of the bandwidth are characterized and plotted on a marginal opportunity curve.

Steep microbial boundstone-dominated plaform margins

NARCIS (Netherlands)

Kenter, J.A.M.; Harris, P.M.; Della Porta, G.P.

2005-01-01

Seaward progradation of several kilometers has been documented mostly for leeward margin low-angle carbonate slope systems with a dominant platform top sediment source. However, steep and high-relief margins fronting deep basins can also prograde and as such are somewhat perplexing. Characteristics

Comparative analysis of intraoral radiographs with variation of tube angulation to detect insufficient crown margins.

Science.gov (United States)

Sailer, Benjamin F; Geibel, Margrit-Ann

2013-01-01

Variations in angulation of the x-ray tube affect the appearance of insufficient approximal crown margins on intraoral radiographs. This study examines the impact of such angular variation on the assessment of digital radiographs using three different X-ray tubes--Heliodent DS (Sirona), Gendex Expert DC (KaVo Dental) and Focus (KaVo Dental)--as well as the Gendex Visualix eHD CCD sensor (KaVo Dental). The test specimens, crowned teeth 46 from two mandibles provided by the Institute of Anatomy and Cell Biology, were examined with each tube. The results indicate great differences in the angles indicative of insufficient crown margins on X-ray images. Because of beam divergence and the crown marginal gap, the length and width of which frequently varies, it is difficult to infer any optimum angle from the data. This leads to the conclusion that at present, it is not possible to establish ideal angles for visualization of insufficient approximal crown margins.

Safety margins and retrofit. The technical calculation perspective; Sicherheitsmargen durch Nachruestung aus Sicht der technischen Berechnung

Energy Technology Data Exchange (ETDEWEB)

Daichendt, Matthias [Kraftanlagen Heidelberg GmbH, Heidelberg (Germany). Systemtechnik - Technische Berechnungen

2016-01-15

Safety margins are an essential factor of the safety philosophy for nuclear power plants. They support to cover future requirements even today. The basic safety concept is one key topic as also aspects of process engineering, the dimensioning and mechanical analysis of systems and ageing management. Calculations with today's capabilities are an integral part of the determination of safety margins. They can be used to analyse and to assess retrofit measures.

Target volume definition for external beam partial breast radiotherapy: Clinical, pathological and technical studies informing current approaches

International Nuclear Information System (INIS)

Kirby, Anna M.; Coles, Charlotte E.; Yarnold, John R.

2010-01-01

Partial breast irradiation (PBI) is currently under investigation in several phase III trials and, following a recent consensus statement, its use off-study may increase despite ongoing uncertainty regarding optimal target volume definition. We review the clinical, pathological and technical evidence for target volume definition in external beam partial breast irradiation (EB-PBI). The optimal method of tumour bed (TB) delineation requires X-ray CT imaging of implanted excision cavity wall markers. The definition of clinical target volume (CTV) as TB plus concentric 15 mm margins is based on the anatomical distribution of multifocal and multicentric disease around the primary tumour in mastectomy specimens, and the clinical locations of local tumour relapse (LR) after breast conservation surgery. If the majority of LR originate from foci of residual invasive and/or intraduct disease in the vicinity of the TB after complete microscopic resection, CTV margin logically takes account of the position of primary tumour within the surgical resection specimen. The uncertain significance of independent primary tumours as sources of preventable LR, and of wound healing responses in stimulating LR, increases the difficulties in defining optimal CTV. These uncertainties may resolve after long-term follow-up of current PBI trials. By contrast, a commonly used 10 mm clinical to planning target volume (PTV) margin has a stronger evidence base, although departmental set-up errors need to be confirmed locally. A CTV-PTV margin >10 mm may be required in women with larger breasts and/or large seromas, whilst the role of image-guided radiotherapy with or without TB markers in reducing CTV-PTV margins needs to be explored.

Higher US crop prices trigger little area expansion so marginal land for biofuel crops is limited

International Nuclear Information System (INIS)

Swinton, Scott M.; Babcock, Bruce A.; James, Laura K.; Bandaru, Varaprasad

2011-01-01

By expanding energy biomass production on marginal lands that are not currently used for crops, food prices increase and indirect climate change effects can be mitigated. Studies of the availability of marginal lands for dedicated bioenergy crops have focused on biophysical land traits, ignoring the human role in decisions to convert marginal land to bioenergy crops. Recent history offers insights about farmer willingness to put non-crop land into crop production. The 2006-09 leap in field crop prices and the attendant 64% gain in typical profitability led to only a 2% increase in crop planted area, mostly in the prairie states. At this rate, a doubling of expected profitability from biomass crops would expand cropland supply by only 3.2%. Yet targets for cellulosic ethanol production in the US Energy Independence and Security Act imply boosting US planted area by 10% or more with perennial biomass crops. Given landowner reluctance to expand crop area with familiar crops in the short run, large scale expansion of the area in dedicated bioenergy crops will likely be difficult and costly to achieve. - Highlights: → Biofuel crops on cropland can displace food crops, reducing food supply and triggering indirect land use. → Growing biofuel crops on non-crop marginal land avoids these problems. → But US farmers expanded cropland by only 2% when crop profitability jumped 64% during 2006-09. → So medium-term availability of marginal lands for biofuel crops is limited and costly.

Conference Report: The New Discovery of Margins: Theory-Based Excursions in Marginal Social Fields

OpenAIRE

Kirchner, Babette; Lorenzen, Jule-Marie; Striffler, Christine

2014-01-01

At this year's spring conference of the Sociology of Knowledge Section of the German Sociological Association, a diverse range of theoretical concepts and multiple empirical insights into different marginal social fields were presented. As in everyday life, drawing a line between center and margin can be seen as an important challenge that must equally be faced in sociology. The socially constructed borderline appears to be highly variable. Therefore it has to be delineated or fixed somehow. ...

Outcome of wide local excision in dermatofibrosarcoma protuberans and use of radiotherapy for margin-positive disease

Directory of Open Access Journals (Sweden)

Raashid Hamid

2013-01-01

Full Text Available Purpose: Wide local excision (WLE is the preferred treatment of dermatofibrosarcoma protuberans (DFSP. The aim is to achieve negtive margins. We followed the impact of radiotherapy used postoperatively for both margin-negative and margin-positive DFSP tumors. Materials and Methods: Outcome of treatment of 36 patients of DFSP treated at our hospital was assessed. Thirty patients received radiotherapy postoperatively and six patients received radiotherapy alone. The maximum dimension of the lesion was 15 cm 2 . Patients were followed up for varying periods of time for any recurrence. Results: 10-year actuarial local control rate was determined. Local control was realized in six patients who were treated with radiotherapy alone. 30 patients were treated by radiotherapy and surgery. Out of these 30 patients, there were 6 local failures (failure rate 10%. Actuarial control rate was 82%. The failures were among patients who had positive margins. Conclusion: Radiotherapy is effective, and it decreases the recurrence rate in the treatment of DFSP. It is especially helpful in margin-positive disease. This appears true for patients treated with radiotherapy alone or radiotherapy used postoperatively.

Evaluating the marginal utility principle for long-term hydropower scheduling

International Nuclear Information System (INIS)

Zhao, Tongtiegang; Zhao, Jianshi; Liu, Pan; Lei, Xiaohui

2015-01-01

Highlights: • Analysis of one-, two- and multi-period hydropower scheduling. • Derivation of marginal cost and marginal return of carry-over storage. • Evaluation of the marginal utility principle in a case study of the Three Gorges Reservoir. - Abstract: The conversion of the potential energy of dammed water into hydropower depends on both reservoir storage and release, which are the major difficulties in hydropower reservoir operation. This study evaluates the marginal utility principle, which determines the optimal carry-over storage between periods, for long-term hydropower scheduling. Increasing marginal cost and decreasing marginal return are two important characteristics that determine the marginal utility principle in water supply. However, the notion of decreasing marginal return is inapplicable in hydropower scheduling. Instead, the carry-over storage from one period has an increasing marginal contribution to the power generation in the next period. Although carry-over storage incurs an increasing marginal cost to the power generation in the current period, the marginal return is higher than the marginal cost. The marginal return from the carry-over storage further increases in the multi-period case. These findings suggest saving as much carry-over storage as possible, which is bounded by the operational constraints of storage capacity, environmental flow, and installed capacity in actual hydropower scheduling. The marginal utility principle is evaluated for a case study of the Three Gorges Reservoir, and the effects of the constraints are discussed. Results confirm the theoretical findings and show that the marginal return from carry-over storage is larger than the marginal cost. The operational constraints help determine the optimal carry-over storage.

Toddler foods, children's foods: assessing sodium in packaged supermarket foods targeted at children.

Science.gov (United States)

Elliott, Charlene D; Conlon, Martin J

2011-03-01

To critically examine child-oriented packaged food products sold in Canada for their sodium content, and to assess them light of intake recommendations, the current policy context and suggested targets. Baby/toddler foods (n 186) and child-oriented packaged foods (n 354) were coded for various attributes (including sodium). Summary statistics were created for sodium, then the children's food products were compared with the UK Food Standards Agency (FSA) 'targets' for sodium in packaged foods. Also assessed were the products' per-serving sodium levels were assessed in light of the US Institute of Medicine's dietary reference intakes and Canada's Food Guide. Calgary, Alberta, Canada. None. Twenty per cent of products could be classified as having high sodium levels. Certain sub-categories of food (i.e. toddler entrées, children's packaged lunches, soups and canned pastas) were problematic. Significantly, when scaled in according to Schedule M or viewed in light of the serving sizes on the Nutrition Facts table, the sodium level in various dry goods products generally fell within, and below, the Adequate Intake (AI)/Tolerable Upper Intake Level (UL) band for sodium. When scaled in accordance with the UK FSA targets, however, none of the (same) products met the targets. In light of AI/UL thresholds based on age and per-serving cut-offs, packaged foodstuffs for youngsters fare relatively well, with the exception of some problematic areas. 'Stealth sodium' and 'subtle sodium' are important considerations; so is use of the FSA's scaling method to evaluate sodium content, because it is highly sensitive to the difference between the reference amount and the actual real-world serving size for the product being considered.

Assessing the relationship between child sexual abuse and marginal living conditions on HIV/AIDS-related risk behavior among women prisoners.

Science.gov (United States)

Mullings, J L; Marquart, J W; Brewer, V E

2000-05-01

There were two aims in this research. First, to examine the relationships between childhood sexual abuse and HIV drug and sexual risk taking behaviors among female prisoners, and second, to examine the relationship between a marginal adult living context and HIV drug and sexual risk taking behavior among female prisoners. The data were collected through face-to-face interviews with a random sample of 500 women at admission to prison in 1994. Differences between women who were sexually abused while growing up (n = 130) were compared to women who reported no sexual abuse (n = 370) along various demographic, and HIV drug and sexual risk taking dimensions. A history of sexual abuse while growing up was associated with increased sexual risk taking behaviors in adulthood. A marginal adult living situation also emerged as an important factor increasing the risk for HIV infection. Examining the co-occurrence of both childhood sexual abuse and adult marginal living context revealed a strong relationship between these two factors and HIV risk taking activities. The findings indicate that childhood sexual abuse may be a predictor for HIV sexual risk taking behaviors among incarcerated women. The marginal and chaotic adult living style of these women was also associated the extent of their HIV drug and sexual risk taking behaviors. Our research suggests that the co-occurrence of sexual victimization and marginality is a stronger predictor of HIV risk than each variable alone.

Improvement of CT-based treatment planning models of abdominal targets using static exhale imaging

International Nuclear Information System (INIS)

Ten Haken, R.K.; Balter, J.M.; Lam, K.L.; McGinn, C.J.; Lawrence, T.S.

1996-01-01

PURPOSE: CT based models of the patient that do not account for the motion of ventilation may not accurately predict the shape and position of critical abdominal structures. Without knowledge of the patient's ventilatory status during the CT scan, a planning target volume margin for the entire range of ventilation is required both inferior and superior to abdominal target volumes to ensure coverage. Also, dose-volume histograms and normal tissue complication probability (NTCP) estimates may be uncertain. Respiratory gating technology for imaging and treatment is not yet widely available. The purpose of the current study is to explore an intermediate step to improve the veracity of the patient model and reduce the treated volume by acquiring the CT data with the patients holding their breath at normal exhale. MATERIALS AND METHODS: The ventilatory time courses of diaphragm movement for 15 patients (with no special breathing instructions) were measured using digitized movies from the fluoroscope during simulation. On repeat simulations, the reproducibility of the diaphragm position at exhale was determined. A clinical protocol was developed for treatment based on exhale CT models. CT scans were acquired at normal exhale using a spiral scanner. Typical volumes were acquired using 5 mm slice thickness and a 1:1 pitch. The scan volume was divided into 2-3 segments, to allow the patient to breathe in between. Margins were placed about intrahepatic target volumes based on the ventilatory excursion inferior to the target, and on only the reproducibility of exhale position superior to the target. RESULTS: The average patient's diaphragm was located within 2 mm of the average exhale position for 50% of the typical ventilatory cycle. For inhale, this value was reduced to 10%, and for mid ventilation, 15%. The reproducibility of exhale position over multiple breathing cycles was 2 mm (2σ), as opposed to 4 mm for inhale. Combining the variation of exhale position and the

Advancements in understanding the aeromagnetic expressions of basin-margin faults—An example from San Luis Basin, Colorado

Science.gov (United States)

Grauch, V. J.; Bedrosian, Paul A.; Drenth, Benjamin J.

2013-01-01

Advancements in aeromagnetic acquisition technology over the past few decades have led to greater resolution of shallow geologic sources with low magnetization, such as intrasedimentary faults and paleochannels. Detection and mapping of intrasedimentary faults in particular can be important for understanding the overall structural setting of an area, even if exploration targets are much deeper. Aeromagnetic methods are especially useful for mapping structures in mountain-piedmont areas at the margins of structural basins, where mineral exploration and seismic-hazard studies may be focused, and where logistical or data-quality issues encumber seismic methods. Understanding if the sources of aeromagnetic anomalies in this context originate from sedimentary units or bedrock is important for evaluating basin structure and/or depth to shallow exploration targets. Advancements in aeromagnetic acquisition technology over the past few decades have led to greater resolution of shallow geologic sources with low magnetization, such as intrasedimentary faults and paleochannels. Detection and mapping of intrasedimentary faults in particular can be important for understanding the overall structural setting of an area, even if exploration targets are much deeper. Aeromagnetic methods are especially useful for mapping structures in mountain-piedmont areas at the margins of structural basins, where mineral exploration and seismic-hazard studies may be focused, and where logistical or data-quality issues encumber seismic methods. Understanding if the sources of aeromagnetic anomalies in this context originate from sedimentary units or bedrock is important for evaluating basin structure and/or depth to shallow exploration targets.

Marginal and internal fit of nano-composite CAD/CAM restorations

Directory of Open Access Journals (Sweden)

So-Hyun Park

2016-02-01

Full Text Available Objectives The purpose of this study was to compare the marginal and internal fit of nano-composite CAD-CAM restorations. Materials and Methods A full veneer crown and an mesio-occluso-distal (MOD inlay cavity, which were prepared on extracted human molars, were used as templates of epoxy resin replicas. The prepared teeth were scanned and CAD-CAM restorations were milled using Lava Ultimate (LU and experimental nano-composite CAD/CAM blocks (EB under the same milling parameters. To assess the marginal and internal fit, the restorations were cemented to replicas and were embedded in an acrylic mold for sectioning at 0.5 mm intervals. The measured gap data were pooled according to the block types and measuring points for statistical analysis. Results Both the block type and measuring point significantly affected gap values, and their interaction was significant (p = 0.000. In crowns and inlays made from the two blocks, gap values were significantly larger in the occlusal area than in the axial area, while gap values in the marginal area were smallest (p < 0.001. Among the blocks, the restorations milled from EB had a significantly larger gap at all measuring points than those milled from LU (p = 0.000. Conclusions The marginal and internal gaps of the two nano-composite CAD/CAM blocks differed according to the measuring points. Among the internal area of the two nano-composite CAD/CAM restorations, occlusal gap data were significantly larger than axial gap data. The EB crowns and inlays had significantly larger gaps than LU restorations.

Margination of Fluorescent Polylactic Acid–Polyaspartamide based Nanoparticles in Microcapillaries In Vitro: the Effect of Hematocrit and Pressure

Directory of Open Access Journals (Sweden)

Emanuela Fabiola Craparo

2017-10-01

Full Text Available The last decade has seen the emergence of vascular-targeted drug delivery systems as a promising approach for the treatment of many diseases, such as cardiovascular diseases and cancer. In this field, one of the major challenges is carrier margination propensity (i.e., particle migration from blood flow to vessel walls; indeed, binding of these particles to targeted cells and tissues is only possible if there is direct carrier–wall interaction. Here, a microfluidic system mimicking the hydrodynamic conditions of human microcirculation in vitro is used to investigate the effect of red blood cells (RBCs on a carrier margination in relation to RBC concentration (hematocrit and pressure drop. As model drug carriers, fluorescent polymeric nanoparticles (FNPs were chosen, which were obtained by using as starting material a pegylated polylactic acid–polyaspartamide copolymer. The latter was synthesized by derivatization of α,β-poly(N-2-hydroxyethyl-d,l-aspartamide (PHEA with Rhodamine (RhB, polylactic acid (PLA and then poly(ethyleneglycol (PEG chains. It was found that the carrier concentration near the wall increases with increasing pressure drop, independently of RBC concentration, and that the tendency for FNP margination decreases with increasing hematocrit. This work highlights the importance of taking into account RBC–drug carrier interactions and physiological conditions in microcirculation when planning a drug delivery strategy based on systemically administered carriers.

From Borders to Margins

DEFF Research Database (Denmark)

Parker, Noel

2009-01-01

of entities that are ever open to identity shifts.  The concept of the margin possesses a much wider reach than borders, and focuses continual attention on the meetings and interactions between a range of indeterminate entities whose interactions may determine both themselves and the types of entity...... upon Deleuze's philosophy to set out an ontology in which the continual reformulation of entities in play in ‘post-international' society can be grasped.  This entails a strategic shift from speaking about the ‘borders' between sovereign states to referring instead to the ‘margins' between a plethora...

Mental Depreciation and Marginal Decision Making

Science.gov (United States)

Heath; Fennema

1996-11-01

We propose that individuals practice "mental depreciation," that is, they implicitly spread the fixed costs of their expenses over time or use. Two studies explore how people spread fixed costs on durable goods. A third study shows that depreciation can lead to two distinct errors in marginal decisions: First, people sometimes invest too much effort to get their money's worth from an expense (e.g., they may use a product a lot to spread the fixed expense across more uses). Second, people sometimes invest too little effort to get their money's worth: When people add a portion of the fixed cost to the current costs, their perceived marginal (i.e., incremental) costs exceed their true marginal costs. In response, they may stop investing because their perceived costs surpass the marginal benefits they are receiving. The latter effect is supported by two field studies that explore real board plan decisions by university students.

Marginal and Interaction Effects in Ordered Response Models

OpenAIRE

Debdulal Mallick

2009-01-01

In discrete choice models the marginal effect of a variable of interest that is interacted with another variable differs from the marginal effect of a variable that is not interacted with any variable. The magnitude of the interaction effect is also not equal to the marginal effect of the interaction term. I present consistent estimators of both marginal and interaction effects in ordered response models. This procedure is general and can easily be extended to other discrete choice models. I ...

Novel targeted agents for gastric cancer

Directory of Open Access Journals (Sweden)

Liu Lian

2012-06-01

Full Text Available Abstract Contemporary advancements have had little impact on the treatment of gastric cancer (GC, the world’s second highest cause of cancer death. Agents targeting human epidermal growth factor receptor mediated pathways have been a common topic of contemporary cancer research, including monoclonal antibodies (mAbs and receptor tyrosine kinase inhibitors (TKIs. Trastuzumab is the first target agent evidencing improvements in overall survival in HER2-positive (human epidermal growth factor receptor 2 gastric cancer patients. Agents targeting vascular epithelial growth factor (VEGF, mammalian target of rapamycin (mTOR, and other biological pathways are also undergoing clinical trials, with some marginally positive results. Effective targeted therapy requires patient selection based on predictive molecular biomarkers. Most phase III clinical trials are carried out without patient selection; therefore, it is hard to achieve personalized treatment and to monitor patient outcome individually. The trend for future clinical trials requires patient selection methods based on current understanding of GC biology with the application of biomarkers.

Recycling issues facing target and RTL materials of inertial fusion designs

International Nuclear Information System (INIS)

El-Guebaly, L.; Wilson, P.; Sawan, M.; Henderson, D.; Varuttamaseni, A.

2005-01-01

Designers of heavy ion (HI) and Z-pinch inertial fusion power plants have explored the potential of recycling the target and recyclable transmission line (RTL) materials as an alternate option to disposal in a geological repository. This work represents the first time a comprehensive recycling assessment was performed on both machines with an exact pulse history. Our results offer two divergent conclusions on the recycling issue. For the HI concept, target recycling is not a 'must' requirement and the preferred option is the one-shot use scenario as target materials represent a small waste stream, less than 1% of the total nuclear island waste. We recommend using low-cost hohlraum materials once-through and then disposing of them instead of recycling expensive materials such as Au and Gd. On the contrary, RTL recycling is a 'must' requirement for the Z-pinch concept in order to minimize the RTL inventory and enhance the economics. The RTLs meet the low level waste and recycling dose requirements with a wide margin when recycled for the entire plant life even without a cooling period. While recycling offers advantages to the Z-pinch system, it adds complexity and cost to the HI designs

The AEROPATH project targeting Pseudomonas aeruginosa: crystallographic studies for assessment of potential targets in early-stage drug discovery

International Nuclear Information System (INIS)

Moynie, Lucille; Schnell, Robert; McMahon, Stephen A.; Sandalova, Tatyana; Boulkerou, Wassila Abdelli; Schmidberger, Jason W.; Alphey, Magnus; Cukier, Cyprian; Duthie, Fraser; Kopec, Jolanta; Liu, Huanting; Jacewicz, Agata; Hunter, William N.; Naismith, James H.; Schneider, Gunter

2012-01-01

A focused strategy has been directed towards the structural characterization of selected proteins from the bacterial pathogen P. aeruginosa. The objective is to exploit the resulting structural data, in combination with ligand-binding studies, and to assess the potential of these proteins for early-stage antimicrobial drug discovery. Bacterial infections are increasingly difficult to treat owing to the spread of antibiotic resistance. A major concern is Gram-negative bacteria, for which the discovery of new antimicrobial drugs has been particularly scarce. In an effort to accelerate early steps in drug discovery, the EU-funded AEROPATH project aims to identify novel targets in the opportunistic pathogen Pseudomonas aeruginosa by applying a multidisciplinary approach encompassing target validation, structural characterization, assay development and hit identification from small-molecule libraries. Here, the strategies used for target selection are described and progress in protein production and structure analysis is reported. Of the 102 selected targets, 84 could be produced in soluble form and the de novo structures of 39 proteins have been determined. The crystal structures of eight of these targets, ranging from hypothetical unknown proteins to metabolic enzymes from different functional classes (PA1645, PA1648, PA2169, PA3770, PA4098, PA4485, PA4992 and PA5259), are reported here. The structural information is expected to provide a firm basis for the improvement of hit compounds identified from fragment-based and high-throughput screening campaigns

Genotypic Resistance Tests Sequences Reveal the Role of Marginalized Populations in HIV-1 Transmission in Switzerland.

Science.gov (United States)

Shilaih, Mohaned; Marzel, Alex; Yang, Wan Lin; Scherrer, Alexandra U; Schüpbach, Jörg; Böni, Jürg; Yerly, Sabine; Hirsch, Hans H; Aubert, Vincent; Cavassini, Matthias; Klimkait, Thomas; Vernazza, Pietro L; Bernasconi, Enos; Furrer, Hansjakob; Günthard, Huldrych F; Kouyos, Roger

2016-06-14

Targeting hard-to-reach/marginalized populations is essential for preventing HIV-transmission. A unique opportunity to identify such populations in Switzerland is provided by a database of all genotypic-resistance-tests from Switzerland, including both sequences from the Swiss HIV Cohort Study (SHCS) and non-cohort sequences. A phylogenetic tree was built using 11,127 SHCS and 2,875 Swiss non-SHCS sequences. Demographics were imputed for non-SHCS patients using a phylogenetic proximity approach. Factors associated with non-cohort outbreaks were determined using logistic regression. Non-B subtype (univariable odds-ratio (OR): 1.9; 95% confidence interval (CI): 1.8-2.1), female gender (OR: 1.6; 95% CI: 1.4-1.7), black ethnicity (OR: 1.9; 95% CI: 1.7-2.1) and heterosexual transmission group (OR:1.8; 95% CI: 1.6-2.0), were all associated with underrepresentation in the SHCS. We found 344 purely non-SHCS transmission clusters, however, these outbreaks were small (median 2, maximum 7 patients) with a strong overlap with the SHCS'. 65% of non-SHCS sequences were part of clusters composed of >= 50% SHCS sequences. Our data suggests that marginalized-populations are underrepresented in the SHCS. However, the limited size of outbreaks among non-SHCS patients in-care implies that no major HIV outbreak in Switzerland was missed by the SHCS surveillance. This study demonstrates the potential of sequence data to assess and extend the scope of infectious-disease surveillance.

Sealing of minimally invasive Class II fillings (slot) using an adhesive patch: sealant margin extension for prevention.

Science.gov (United States)

Schmidlin, Patrick R; Seemann, Rainer; Filli, Tilla; Attin, Thomas; Imfeld, Thomas

2007-01-01

A laboratory study was performed to assess the potential of an adhesive patch to seal small, unbeveled, Class II, box-only (slot) composite fillings. After minimal access cavity preparation with an 80 pm diamond bur, 40 box-only Class II cavities were prepared mesially and distally in 20 extracted human molars using a u-shaped PCS insert (EMS). One cavity per tooth was adhesively filled with a hybrid composite material in one increment. A patch, acting as an adhesive matrice, was applied to the other cavity of each tooth to seal the restoration. The margin of the patch was located in areas easily accessible to oral hygiene measures and self-cleaning. All the teeth were subjected to thermo-mechanical stress in a computer-controlled masticator device. In 10 teeth, caries was induced in a microbial-based artificial mouth model and quantitatively determined by confocal laser scanning microscopy. Microleakage was assessed in the other 10 teeth in two planar sections after immersion in 0.5% basic fuchsin solution. The results showed no demineralization at the filling margins protected with the patch. Microleakage was observed in one sample only and was limited to the enamel. In contrast, the margins of fillings without the patch application showed a mean demineralization depth of 146 +/- 42 microm and dye penetration into the dentin in five sections. This innovative approach to sealing restorative margins with an adhesive patch results in less leakage and filling margin demineralization and merits further investigation.

Advancing optical imaging for breast margin assessment: an analysis of excisional time, cautery, and patent blue dye on underlying sources of contrast.

Directory of Open Access Journals (Sweden)

Torre M Bydlon

Full Text Available Breast conserving surgery (BCS is a recommended treatment for breast cancer patients where the goal is to remove the tumor and a surrounding rim of normal tissue. Unfortunately, a high percentage of patients return for additional surgeries to remove all of the cancer. Post-operative pathology is the gold standard for evaluating BCS margins but is limited due to the amount of tissue that can be sampled. Frozen section analysis and touch-preparation cytology have been proposed to address the surgical needs but also have sampling limitations. These issues represent an unmet clinical need for guidance in resecting malignant tissue intra-operatively and for pathological sampling. We have developed a quantitative spectral imaging device to examine margins intra-operatively. The context in which this technology is applied (intra-operative or post-operative setting is influenced by time after excision and surgical factors including cautery and the presence of patent blue dye (specifically Lymphazurin™, used for sentinel lymph node mapping. Optical endpoints of hemoglobin ([THb], fat ([β-carotene], and fibroglandular content via light scattering ( measurements were quantified from diffuse reflectance spectra of lumpectomy and mastectomy specimens using a Monte Carlo model. A linear longitudinal mixed-effects model was used to fit the optical endpoints for the cautery and kinetics studies. Monte Carlo simulations and tissue mimicking phantoms were used for the patent blue dye experiments. [THb], [β-carotene], and were affected by , and [β-carotene]/ was 40%. [β-carotene] and [β-carotene]/ were the only parameters not affected by cautery. This work demonstrates the importance of understanding the post-excision kinetics of ex-vivo tissue and the presence of cautery and patent blue dye for breast tumor margin assessment, to accurately interpret data and exploit underling sources of contrast.

Maximum margin semi-supervised learning with irrelevant data.

Science.gov (United States)

Yang, Haiqin; Huang, Kaizhu; King, Irwin; Lyu, Michael R

2015-10-01

Semi-supervised learning (SSL) is a typical learning paradigms training a model from both labeled and unlabeled data. The traditional SSL models usually assume unlabeled data are relevant to the labeled data, i.e., following the same distributions of the targeted labeled data. In this paper, we address a different, yet formidable scenario in semi-supervised classification, where the unlabeled data may contain irrelevant data to the labeled data. To tackle this problem, we develop a maximum margin model, named tri-class support vector machine (3C-SVM), to utilize the available training data, while seeking a hyperplane for separating the targeted data well. Our 3C-SVM exhibits several characteristics and advantages. First, it does not need any prior knowledge and explicit assumption on the data relatedness. On the contrary, it can relieve the effect of irrelevant unlabeled data based on the logistic principle and maximum entropy principle. That is, 3C-SVM approaches an ideal classifier. This classifier relies heavily on labeled data and is confident on the relevant data lying far away from the decision hyperplane, while maximally ignoring the irrelevant data, which are hardly distinguished. Second, theoretical analysis is provided to prove that in what condition, the irrelevant data can help to seek the hyperplane. Third, 3C-SVM is a generalized model that unifies several popular maximum margin models, including standard SVMs, Semi-supervised SVMs (S(3)VMs), and SVMs learned from the universum (U-SVMs) as its special cases. More importantly, we deploy a concave-convex produce to solve the proposed 3C-SVM, transforming the original mixed integer programming, to a semi-definite programming relaxation, and finally to a sequence of quadratic programming subproblems, which yields the same worst case time complexity as that of S(3)VMs. Finally, we demonstrate the effectiveness and efficiency of our proposed 3C-SVM through systematical experimental comparisons. Copyright �

Number of fragments, margin status and thermal artifacts of conized specimens from LLETZ surgery to treat cervical intraepithelial neoplasia.

Science.gov (United States)

Bittencourt, Dulcimary Dias; Zanine, Rita Maira; Sebastião, Ana Martins; Taha, Nabiha Saadi; Speck, Neila Góis; Ribalta, Julisa Chamorro Lascasas

2012-01-01

Large loop excision of the transformation zone (LLETZ) is a nontraumatic cut and coagulation method with several advantages, but it induces thermal artifacts in the cut region. The aim here was to assess the correlations of age, number of fragments, lesion grade and degree of thermal artifacts with margin quality in conized specimens from LLETZ for cervical intraepithelial neoplasia (CIN). Cross-sectional study at Universidade Federal de São Paulo (Unifesp). The records and histopathology findings of 118 women who underwent LLETZ between 1999 and 2007 were reviewed. Age, number of fragments, lesion grade, degree of thermal artifacts and margin quality were assessed. The patients' mean age was 27.14 years; 63.6% had been diagnosed with CIN II and 36.4% with CIN III. The lesion was removed as a single fragment in 79.6% of the cases. The margins were free from intraepithelial neoplasia in 85.6% and compromised in the endocervical margin in 6.8%. Fragment damage due to artifacts occurred in 2.5%. Severe artifacts occurred in 22.8%. Women aged 30 years or over presented more cases of CIN III (P < 0.0004). Neoplastic compromising of surgical margins and severe artifacts occurred more often in cases in which two or more fragments were removed, and in patients aged 30 years or over. CIN III in women aged 30 or over, when removed in two or more fragments during LLETZ, presented a greater number of compromised margins and greater severity of thermal artifacts.

Setup uncertainties in linear accelerator based stereotactic radiosurgery and a derivation of the corresponding setup margin for treatment planning.

Science.gov (United States)

Zhang, Mutian; Zhang, Qinghui; Gan, Hua; Li, Sicong; Zhou, Su-min

2016-02-01

In the present study, clinical stereotactic radiosurgery (SRS) setup uncertainties from image-guidance data are analyzed, and the corresponding setup margin is estimated for treatment planning purposes. Patients undergoing single-fraction SRS at our institution were localized using invasive head ring or non-invasive thermoplastic masks. Setup discrepancies were obtained from an in-room x-ray patient position monitoring system. Post treatment re-planning using the measured setup errors was performed in order to estimate the individual target margins sufficient to compensate for the actual setup errors. The formula of setup margin for a general SRS patient population was derived by proposing a correlation between the three-dimensional setup error and the required minimal margin. Setup errors of 104 brain lesions were analyzed, in which 81 lesions were treated using an invasive head ring, and 23 were treated using non-invasive masks. In the mask cases with image guidance, the translational setup uncertainties achieved the same level as those in the head ring cases. Re-planning results showed that the margins for individual patients could be smaller than the clinical three-dimensional setup errors. The derivation of setup margin adequate to address the patient setup errors was demonstrated by using the arbitrary planning goal of treating 95% of the lesions with sufficient doses. With image guidance, the patient setup accuracy of mask cases can be comparable to that of invasive head rings. The SRS setup margin can be derived for a patient population with the proposed margin formula to compensate for the institution-specific setup errors. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Exploring the Margin Recipe for Online Adaptive Radiation Therapy for Intermediate-Risk Prostate Cancer: An Intrafractional Seminal Vesicles Motion Analysis

Energy Technology Data Exchange (ETDEWEB)

Sheng, Yang, E-mail: Yang.Sheng@duke.edu [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States); Medical Physics Graduate Program, Duke University, Durham, North Carolina (United States); Li, Taoran [Medical Physics Graduate Program, Duke University, Durham, North Carolina (United States); Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, Pennsylvania (United States); Lee, W. Robert [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States); Yin, Fang-Fang; Wu, Q. Jackie [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States); Medical Physics Graduate Program, Duke University, Durham, North Carolina (United States)

2017-06-01

Purpose: To provide a benchmark for seminal vesicle (SV) margin selection to account for intrafractional motion and to investigate the effectiveness of 2 motion surrogates in predicting intrafractional SV coverage. Methods and Materials: Fifteen prostate patients were studied. Each patient had 5 pairs (1 patient had 4 pairs) of pretreatment and posttreatment cone beam CTs (CBCTs). Each pair of CBCTs was registered on the basis of prostate fiducial markers. All pretreatment SVs were expanded with 1-, 2-, 3-, 4-, 5-, and 8-mm isotropic margins to form a series of planning target volumes, and their intrafractional coverage to the posttreatment SV determined the “ground truth” for exact coverage. Two motion surrogates, the center of mass (COM) and the border of contour, were evaluated by the use of Pearson product-moment correlation coefficient and exponential fitting for predicting SV underdosage. Action threshold of each surrogate was calculated. The margin for each surrogate was calculated according to a traditional margin recipe. Results: Ninety-five percent posttreatment SV coverage was achieved in 9%, 53%, 73%, 86%, 95%, and 97% of fractions with 1-, 2-, 3-, 4-, 5-, and 8-mm margins, respectively. The 5-mm margins provided 95% intrafractional SV coverage in over 90% of fractions. The correlation between the COM and border was weak, moderate, and strong in the left-right (L-R), anterior-posterior (A-P), and superior-inferior (S-I) directions, respectively. Exponential fitting gave the underdosage threshold of 4.5 and 7.0 mm for the COM and border. The Van Herk margin recipe recommended 0-, 0.5-, and 0.8-mm margins in the L-R, A-P, and S-I directions based on the COM, and 1.2-, 3.9-, and 2.5-mm margins based on the border. Conclusions: Five-millimeter isotropic margins for the SV constitute the minimum required to mitigate the intrafractional motion. Both the COM and the border are acceptable predictors for SV underdosage with 4.5- and 7.0-mm action threshold

Positive Surgical Margins in Favorable-Stage Differentiated Thyroid Cancer.

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Mercado, Catherine E; Drew, Peter A; Morris, Christopher G; Dziegielewski, Peter T; Mendenhall, William M; Amdur, Robert J

2018-04-16

The significance of positive margin in favorable-stage well-differentiated thyroid cancer is controversial. We report outcomes of positive-margin patients with a matched-pair comparison to a negative-margin group. A total of 25 patients with classic-histology papillary or follicular carcinoma, total thyroidectomy +/- node dissection, stage T1-3N0-1bM0, positive surgical margin at primary site, adjuvant radioactive iodine (I-131), and age older than 18 years were treated between 2003 and 2013. Endpoints were clinical and biochemical (thyroglobulin-only) recurrence-free survival. Matched-pair analysis involved a 1:1 match with negative-margin cases matched for overall stage and I-131 dose. Recurrence-free survival in positive-margin patients was 71% at 10 years. No patient was successfully salvaged with additional treatment. Only 1 patient died of thyroid cancer. Recurrence-free survival at 10 years was worse with a positive (71%) versus negative (90%) margin (P=0.140). Cure with a microscopically positive margin was suboptimal (71%) despite patients having classic-histology papillary and follicular carcinoma, favorable stage, and moderate-dose I-131 therapy.

Learning Convex Inference of Marginals

OpenAIRE

Domke, Justin

2012-01-01

Graphical models trained using maximum likelihood are a common tool for probabilistic inference of marginal distributions. However, this approach suffers difficulties when either the inference process or the model is approximate. In this paper, the inference process is first defined to be the minimization of a convex function, inspired by free energy approximations. Learning is then done directly in terms of the performance of the inference process at univariate marginal prediction. The main ...

Determination of acrylamide levels in potato crisps and other snacks and exposure risk assessment through a Margin of Exposure approach.

Science.gov (United States)

Esposito, Francesco; Nardone, Antonio; Fasano, Evelina; Triassi, Maria; Cirillo, Teresa

2017-10-01

Potato crisps, corn-based extruded snacks and other savoury snacks are very popular products especially among younger generations. These products could be a potential source of acrylamide (AA), a toxic compound which could develop during frying and baking processes. The purpose of this study was the assessment of the dietary intake to AA across six groups of consumers divided according to age through the consumption of potato crisps and other snacks, in order to eventually evaluate the margin of exposure (MOE) related to neurotoxic and carcinogenic critical endpoints. Different brands of potato crisps and other popular snacks were analyzed through a matrix solid-phase dispersion method followed by a bromination step and GC-MS quantification. The concentration of detected AA ranged from 21 to 3444 ng g - 1 and the highest level occurred in potato crisps samples which showed a median value of 968 ng g - 1 . The risk characterization through MOE assessment revealed that five out of six consumers groups showed higher exposure values associated with an augmented carcinogenic risk. Copyright © 2017 Elsevier Ltd. All rights reserved.

Marginal adaptation and CAD-CAM technology: A systematic review of restorative material and fabrication techniques.

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Papadiochou, Sofia; Pissiotis, Argirios L

2018-04-01

The comparative assessment of computer-aided design and computer-aided manufacturing (CAD-CAM) technology and other fabrication techniques pertaining to marginal adaptation should be documented. Limited evidence exists on the effect of restorative material on the performance of a CAD-CAM system relative to marginal adaptation. The purpose of this systematic review was to investigate whether the marginal adaptation of CAD-CAM single crowns, fixed dental prostheses, and implant-retained fixed dental prostheses or their infrastructures differs from that obtained by other fabrication techniques using a similar restorative material and whether it depends on the type of restorative material. An electronic search of English-language literature published between January 1, 2000, and June 30, 2016, was conducted of the Medline/PubMed database. Of the 55 included comparative studies, 28 compared CAD-CAM technology with conventional fabrication techniques, 12 contrasted CAD-CAM technology and copy milling, 4 compared CAD-CAM milling with direct metal laser sintering (DMLS), and 22 investigated the performance of a CAD-CAM system regarding marginal adaptation in restorations/infrastructures produced with different restorative materials. Most of the CAD-CAM restorations/infrastructures were within the clinically acceptable marginal discrepancy (MD) range. The performance of a CAD-CAM system relative to marginal adaptation is influenced by the restorative material. Compared with CAD-CAM, most of the heat-pressed lithium disilicate crowns displayed equal or smaller MD values. Slip-casting crowns exhibited similar or better marginal accuracy than those fabricated with CAD-CAM. Cobalt-chromium and titanium implant infrastructures produced using a CAD-CAM system elicited smaller MD values than zirconia. The majority of cobalt-chromium restorations/infrastructures produced by DMLS displayed better marginal accuracy than those fabricated with the casting technique. Compared with copy

Spectrum estimation method based on marginal spectrum

International Nuclear Information System (INIS)

Cai Jianhua; Hu Weiwen; Wang Xianchun

2011-01-01

FFT method can not meet the basic requirements of power spectrum for non-stationary signal and short signal. A new spectrum estimation method based on marginal spectrum from Hilbert-Huang transform (HHT) was proposed. The procession of obtaining marginal spectrum in HHT method was given and the linear property of marginal spectrum was demonstrated. Compared with the FFT method, the physical meaning and the frequency resolution of marginal spectrum were further analyzed. Then the Hilbert spectrum estimation algorithm was discussed in detail, and the simulation results were given at last. The theory and simulation shows that under the condition of short data signal and non-stationary signal, the frequency resolution and estimation precision of HHT method is better than that of FFT method. (authors)

Systematic Identification and Assessment of Therapeutic Targets for Breast Cancer Based on Genome-Wide RNA Interference Transcriptomes

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Yang Liu

2017-02-01

Full Text Available With accumulating public omics data, great efforts have been made to characterize the genetic heterogeneity of breast cancer. However, identifying novel targets and selecting the best from the sizeable lists of candidate targets is still a key challenge for targeted therapy, largely owing to the lack of economical, efficient and systematic discovery and assessment to prioritize potential therapeutic targets. Here, we describe an approach that combines the computational evaluation and objective, multifaceted assessment to systematically identify and prioritize targets for biological validation and therapeutic exploration. We first establish the reference gene expression profiles from breast cancer cell line MCF7 upon genome-wide RNA interference (RNAi of a total of 3689 genes, and the breast cancer query signatures using RNA-seq data generated from tissue samples of clinical breast cancer patients in the Cancer Genome Atlas (TCGA. Based on gene set enrichment analysis, we identified a set of 510 genes that when knocked down could significantly reverse the transcriptome of breast cancer state. We then perform multifaceted assessment to analyze the gene set to prioritize potential targets for gene therapy. We also propose drug repurposing opportunities and identify potentially druggable proteins that have been poorly explored with regard to the discovery of small-molecule modulators. Finally, we obtained a small list of candidate therapeutic targets for four major breast cancer subtypes, i.e., luminal A, luminal B, HER2+ and triple negative breast cancer. This RNAi transcriptome-based approach can be a helpful paradigm for relevant researches to identify and prioritize candidate targets for experimental validation.

Potential for Conservation Agriculture in the Dry Marginal Zone of Central Syria: A Preliminary Assessment

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Baqir Lalani

2018-02-01

Full Text Available This paper reports on early soil related outcomes from conservation agriculture (CA benchmark sites located within the marginal rainfed environment of agro-ecological zone 4 (annual rainfall: 200–250 mm in pre-conflict central Syria. The outcomes reported are specifically those that relate to beneficial soil quality and water retention attributes relative to conventional tillage-based soil management practices applied to the fodder barley–livestock system, the dominant system in the zone. On-farm operational research was established to examine the impact of a barley (Hordeum vulgare and vetch (Vicia sativa rotation intercropped with atriplex (Atriplex halimus and salsola (Salsola collina, under CA and conventional tillage agriculture, on the soil quality parameters and crop productivity. Preliminary results showed that CA had a positive effect on the soil quality parameters and crop performance. The soil moisture and hydraulic conductivity were higher under CA (p < 0.05, combined with improved productivity (grain and above-ground biomass under specific crop mixes. The results suggest that despite the marginal nature of the zone, the use of CA is a viable option for the future of farmers’ livelihoods within similar localities and agro-climates, given the benefits for soil moisture and grain and straw productivity. In addition, it is likely to positively impact those in marginal environments where both pastoralism and agro-pastoralism production systems co-exist and compete for crop biomass as a main source of livestock feed. The increase in grain and straw yields vis-à-vis improvements in biophysical parameters in the CA system relative to tillage agriculture does suggest, however, that the competition with livestock for biomass is likely to reduce over time, and farmers would be able to return increased levels of straw (as stubble and residue as mulch, given improved biomass yields.

Thermal margin model for transition core of KSNP

International Nuclear Information System (INIS)

Nahm, Kee Yil; Lim, Jong Seon; Park, Sung Kew; Chun, Chong Kuk; Hwang, Sun Tack

2004-01-01

The PLUS7 fuel was developed with mixing vane grids for KSNP. For the transition core partly loaded with the PLUS7 fuels, the procedure to set up the optimum thermal margin model of the transition core was suggested by introducing AOPM concept into the screening method which determines the limiting assembly. According to the procedure, the optimum thermal margin model of the first transition core was set up by using a part of nuclear data for the first transition and the homogeneous core with PLUS7 fuels. The generic thermal margin model of PLUS7 fuel was generated with the AOPM of 138%. The overpower penalties on the first transition core were calculated to be 1.0 and 0.98 on the limiting assembly and the generic thermal margin model, respectively. It is not usual case to impose the overpower penalty on reload cores. It is considered that the lack of channel flow due to the difference of pressure drop between PLUS7 and STD fuels results in the decrease of DNBR. The AOPM of the first transition core is evaluated to be about 135% by using the optimum generic thermal margin model which involves the generic thermal margin model and the total overpower penalty. The STD fuel is not included among limiting assembly candidates in the second transition core, because they have much lower pin power than PLUS7 fuels. The reduced number of STD fuels near the limiting assembly candidates the flow from the limiting assembly to increase the thermal margin for the second transition core. It is expected that cycle specific overpower penalties increase the thermal margin for the transition core. Using the procedure to set up the optimum thermal margin model makes sure that the enhanced thermal margin of PLUS7 fuel can be sufficiently applied to not only the homogeneous core but also the transition core

Reconstructing Rodinia by Fitting Neoproterozoic Continental Margins

Science.gov (United States)

Stewart, John H.

2009-01-01

Reconstructions of Phanerozoic tectonic plates can be closely constrained by lithologic correlations across conjugate margins by paleontologic information, by correlation of orogenic belts, by paleomagnetic location of continents, and by ocean floor magmatic stripes. In contrast, Proterozoic reconstructions are hindered by the lack of some of these tools or the lack of their precision. To overcome some of these difficulties, this report focuses on a different method of reconstruction, namely the use of the shape of continents to assemble the supercontinent of Rodinia, much like a jigsaw puzzle. Compared to the vast amount of information available for Phanerozoic systems, such a limited approach for Proterozoic rocks, may seem suspect. However, using the assembly of the southern continents (South America, Africa, India, Arabia, Antarctica, and Australia) as an example, a very tight fit of the continents is apparent and illustrates the power of the jigsaw puzzle method. This report focuses on Neoproterozoic rocks, which are shown on two new detailed geologic maps that constitute the backbone of the study. The report also describes the Neoproterozoic, but younger or older rocks are not discussed or not discussed in detail. The Neoproterozoic continents and continental margins are identified based on the distribution of continental-margin sedimentary and magmatic rocks that define the break-up margins of Rodinia. These Neoproterozoic continental exposures, as well as critical Neo- and Meso-Neoproterozoic tectonic features shown on the two new map compilations, are used to reconstruct the Mesoproterozoic supercontinent of Rodinia. This approach differs from the common approach of using fold belts to define structural features deemed important in the Rodinian reconstruction. Fold belts are difficult to date, and many are significantly younger than the time frame considered here (1,200 to 850 Ma). Identifying Neoproterozoic continental margins, which are primarily

High efficiency diffusion molecular retention tumor targeting.

Directory of Open Access Journals (Sweden)

Yanyan Guo

Full Text Available Here we introduce diffusion molecular retention (DMR tumor targeting, a technique that employs PEG-fluorochrome shielded probes that, after a peritumoral (PT injection, undergo slow vascular uptake and extensive interstitial diffusion, with tumor retention only through integrin molecular recognition. To demonstrate DMR, RGD (integrin binding and RAD (control probes were synthesized bearing DOTA (for (111 In(3+, a NIR fluorochrome, and 5 kDa PEG that endows probes with a protein-like volume of 25 kDa and decreases non-specific interactions. With a GFP-BT-20 breast carcinoma model, tumor targeting by the DMR or i.v. methods was assessed by surface fluorescence, biodistribution of [(111In] RGD and [(111In] RAD probes, and whole animal SPECT. After a PT injection, both probes rapidly diffused through the normal and tumor interstitium, with retention of the RGD probe due to integrin interactions. With PT injection and the [(111In] RGD probe, SPECT indicated a highly tumor specific uptake at 24 h post injection, with 352%ID/g tumor obtained by DMR (vs 4.14%ID/g by i.v.. The high efficiency molecular targeting of DMR employed low probe doses (e.g. 25 ng as RGD peptide, which minimizes toxicity risks and facilitates clinical translation. DMR applications include the delivery of fluorochromes for intraoperative tumor margin delineation, the delivery of radioisotopes (e.g. toxic, short range alpha emitters for radiotherapy, or the delivery of photosensitizers to tumors accessible to light.

The effects of photodynamic laser therapy in the treatment of marginal chronic periodontitis

Science.gov (United States)

Chifor, Radu; Badea, Iulia; Avram, Ramona; Chifor, Ioana; Badea, Mîndra Eugenia

2016-03-01

The aim of this study was to assess the effects of the antimicrobial photodynamic laser therapy performed during the treatment of deep periodontal disease by using 40 MHz high frequency ultrasonography. The periodontal data recorded during the clinical examination before each treatment session were compared with volumetric changes of the gingiva measured on periodontal ultrasound images. The results show a significant decrease of gingival tissue inflammation proved both by a significant decrease of bleeding on probing as well as by a decrease of the gingival tissues volume on sites where the laser therapy was performed. Periodontal tissues that benefit of laser therapy besides classical non-surgical treatment showed a significant clinical improvement of periodontal status. Based on these findings we were able to conclude that the antimicrobial photodynamic laser therapy applied on marginal periodontium has important anti-inflamatory effect. The periodontal ultrasonography is a method which can provide useful data for assessing the volume changes of gingival tissues, allowing a precise monitoring of marginal periodontitis.

Does IGRT ensure target dose coverage of head and neck IMRT patients?

International Nuclear Information System (INIS)

Graff, Pierre; Hu Weigang; Yom, Sue S.; Pouliot, Jean

2012-01-01

Purpose: To determine if image-guided radiotherapy (IGRT) ensures dose coverage to the target, and to assess the dosimetric impact of anatomic changes using megavoltage cone-beam CT (MVCBCT) for patient positioning during head and neck IMRT. Methods and materials: Forty-eight MVCBCT from 10 head and neck IMRT/IGRT patients were analyzed off-line. Target volumes and organs at risk (OARs) contours delineated on CT were transferred and adjusted on MVCBCT images. Each MVCBCT was processed to allow dose recalculation, resulting in 469 dose–volume histograms (DVHs). The concept of dosimetric latitude was introduced to provide a clinical perspective. Results: MVCBCT target DVHs showed a moderate level of difference in D95 (dose to ⩾95% of volume), generally less than a 5% difference from the planned dose. Delivered-dose increases to the spinal cord and brainstem showed no apparent time trend. The 4 mm margin around OARs was a useful precaution to prevent exceeding critical dose thresholds. The parotid glands showed progressive increases in mean dose related to shrinkage of the external contours. Conclusion: IGRT repositioning ensured target volume coverage, but significant dose variations were observed for OARs. The dosimetric impact of anatomic changes during radiotherapy was of lesser importance than the effects of IGRT repositioning.

Margins in breast conserving surgery: The financial cost & potential savings associated with the new margin guidelines.

Science.gov (United States)

Singer, Lauren; Brown, Eric; Lanni, Thomas

2016-08-01

In this study, we compare the indications for re-excision, the findings of additional tumor in the re-excision specimen as they relate to margin status, and costs associated with re-excision based on recent new consensus statements. A retrospective analysis was performed on 462 patients with invasive breast carcinoma who underwent at least one lumpectomy between January 2011 and December 2013. Postoperative data was analyzed based on where additional disease was found, as it relates to the margin status of the initial lumpectomy and the additional direct costs associated with additional procedures. Of the 462 patients sampled, 149 underwent a re-excision surgery (32.2%). Four patients underwent mastectomy as their second operation. In the 40 patients with additional disease found on re-excision, 36 (90.0%) of them had a positive margin on their initial lumpectomy. None of the four mastectomy patients had residual disease. The mean cost of the initial lumpectomy for all 462 patients was $2118.01 plus an additional $1801.92 for those who underwent re-excision. A positive margin was most predictive of finding residual tumor on re-excision as would be expected. Using old criteria only 0.07% (4/61) of patients who had undergone re-excision with a 'clear' margin, had additional tumor found, at a total cost of $106,354.11. Thus, the new consensus guidelines will lead to less overall cost, at no clinical risk to patients while reducing a patient's surgical risk and essentially eliminating delays in adjuvant care. Copyright © 2016 Elsevier Ltd. All rights reserved.

Splenic marginal zone lymphoma: from genetics to management.

Science.gov (United States)

Arcaini, Luca; Rossi, Davide; Paulli, Marco

2016-04-28

Splenic marginal zone lymphoma (SMZL) is a rare B-cell malignancy involving the spleen, bone marrow, and frequently the blood. SMZL lymphomagenesis involves antigen and/or superantigen stimulation and molecular deregulation of genes (NOTCH2 and KLF2) involved in the physiological differentiation of spleen marginal zone B cells. Diagnosis requires either spleen histology or, alternatively, the documentation of a typical cell morphology and immunophenotype on blood cells coupled with the detection of intrasinusoidal infiltration by CD20(+) cells in the bone marrow. Among B-cell tumors, deletion of 7q and NOTCH2 mutations are almost specific lesions of SMZL, thus representing promising diagnostic biomarkers of this lymphoma. Although the majority of SMZLs show an indolent course with a median survival of approximately 10 years, nearly 30% of patients experience a poor outcome. No randomized trials are reported for SMZL, and few prospective trials are available. A watch-and-wait approach is advisable for asymptomatic patients. Treatment options for symptomatic patients ranges from splenectomy to rituximab alone or combined with chemotherapy. In some geographic areas, a subset of patients with SMZL associates with hepatitis C virus infection, prompting virus eradication as an effective lymphoma treatment. It would be worthwhile to explore deregulated cellular programs of SMZL as therapeutic targets in the future; improved clinical and biological prognostication will be essential for identifying patients who may benefit from novel approaches. © 2016 by The American Society of Hematology.

Clinical variability of target volume description and treatment plans in conformal radiotherapy in muscle invasive bladder cancer

International Nuclear Information System (INIS)

Logue, John P; Sharrock, Carole L; Cowan, Richard A.; Read, Graham; Marrs, Julie; Mott, David

1996-01-01

Purpose/Objective: The delineation of tumor and the production of a treatment plan to encompass this is the prime step in radiotherapy planning. Conformal radiotherapy is developing rapidly and although plentiful research has addressed the implementation of the radiotherapy prescription, scant attention has been made to the fundamental step of production, by the clinician, of an appropriate target volume. As part of an ongoing randomized trial of conformal radiotherapy, in bladder cancer, we have therefore assessed the interphysician variability of radiologists and radiation oncologists (RO) in assessing Gross Tumor Volume(GTV) (ICRU 50) and the adherence of the radiation oncologists to the study protocol of producing a Planning Target Volume (PTV). Materials and Methods: Four patients with T3 carcinoma of bladder who had been entered into the trial were identified. The clinical details, MR scans and CT scans were made available. Eight RO and 3 dedicated diagnostic oncology radiologists were invited to directly outline the GTV onto CT images on a planning computer consul. The RO in addition created a PTV following the trial protocol of 15mm margin around the GTV. Three RO sub-specialized in Urological radiotherapy; all RO had completed training. Volumes were produced, for each clinician, and comparison of these volumes and their isocenters were analyzed. In addition the margins allowed were measured and compared. Results: There was a maximum variation ratio (largest to smallest volume outlined) of the GTV in the four cases of 1.74 among radiologists and 3.74 among oncologists. There was a significant difference (p=0.01) in mean GTV between RO and the radiologists. The mean GTV of the RO exceeded the radiologists by a factor of 1.29 with a mean difference of 13.4 cm 3 The between observer variance within speciality comprised only 9.9% of the total variance in the data having accounted for case and observers speciality. The variation ratio in PTV among oncologists

Plasticity margin recovery during annealing after cold deformation

International Nuclear Information System (INIS)

Bogatov, A.A.; Smirnov, S.V.; Kolmogorov, V.L.

1978-01-01

Restoration of the plasticity margin in steel 20 after cold deformation and annealing at 550 - 750 C and soaking for 5 - 300 min was investigated. The conditions of cold deformation under which the metal acquires microdefects unhealed by subsequent annealing were determined. It was established that if the degree of utilization of the plasticity margin is psi < 0.5, the plasticity margin in steel 20 can be completely restored by annealing. A mathematical model of restoration of the plasticity margin by annealing after cold deformation was constructed. A statistical analysis showed good agreement between model and experiment

A gene signature in histologically normal surgical margins is predictive of oral carcinoma recurrence

International Nuclear Information System (INIS)

Reis, Patricia P; Simpson, Colleen; Goldstein, David; Brown, Dale; Gilbert, Ralph; Gullane, Patrick; Irish, Jonathan; Jurisica, Igor; Kamel-Reid, Suzanne; Waldron, Levi; Perez-Ordonez, Bayardo; Pintilie, Melania; Galloni, Natalie Naranjo; Xuan, Yali; Cervigne, Nilva K; Warner, Giles C; Makitie, Antti A

2011-01-01

Oral Squamous Cell Carcinoma (OSCC) is a major cause of cancer death worldwide, which is mainly due to recurrence leading to treatment failure and patient death. Histological status of surgical margins is a currently available assessment for recurrence risk in OSCC; however histological status does not predict recurrence, even in patients with histologically negative margins. Therefore, molecular analysis of histologically normal resection margins and the corresponding OSCC may aid in identifying a gene signature predictive of recurrence. We used a meta-analysis of 199 samples (OSCCs and normal oral tissues) from five public microarray datasets, in addition to our microarray analysis of 96 OSCCs and histologically normal margins from 24 patients, to train a gene signature for recurrence. Validation was performed by quantitative real-time PCR using 136 samples from an independent cohort of 30 patients. We identified 138 significantly over-expressed genes (> 2-fold, false discovery rate of 0.01) in OSCC. By penalized likelihood Cox regression, we identified a 4-gene signature with prognostic value for recurrence in our training set. This signature comprised the invasion-related genes MMP1, COL4A1, P4HA2, and THBS2. Over-expression of this 4-gene signature in histologically normal margins was associated with recurrence in our training cohort (p = 0.0003, logrank test) and in our independent validation cohort (p = 0.04, HR = 6.8, logrank test). Gene expression alterations occur in histologically normal margins in OSCC. Over-expression of the 4-gene signature in histologically normal surgical margins was validated and highly predictive of recurrence in an independent patient cohort. Our findings may be applied to develop a molecular test, which would be clinically useful to help predict which patients are at a higher risk of local recurrence

Preliminary study of the internal margin of the gross tumor volume in thoracic esophageal cancer

International Nuclear Information System (INIS)

Li, Jiancheng; Pan, Jianji; Wang, Linhua; Zhao, Yunhui; Liu, Di; Chen, Cheng; Zhang, He Ping; Wang, Xiaoliang

2012-01-01

Purpose. - To measure the displacement of the tumor of the gross tumor volume (GTV) of thoracic esophageal cancer in the calm states of end-inspiration and end-expiration for determining the internal margin of the GTV (IGTV). Methods. - Twenty-two patients with thoracic esophageal cancer who were unable to undergo surgery were identified in our hospital. The patients received radiotherapy. By using 16-slice spiral computed tomography (CT), we acquired the calm states of end-inspiration and end-expiration. The displacement and volume changes in tumor target volume were measured, and the changes were analyzed to determine if these were associated with the tidal volume and the location and length of the target volume V. In the end, we analyzed the displacement of tumor target volume and calculated the internal margin of the GTV by empirical formula. Results. - The average tidal volume was 463.6 ml. The average GTV at end-inspiration was 33.3 ml and at end-expiration was 33.35 ml. Three was not any significant between two groups (T -0.034, P > 0.05). The IGTV (X-axis direction) was 3.09 mm for the right sector and 4.08 mm for the left border; the IGTV (Z-axis direction) was 3.96 mm for the anterior border and 2.83 mm for the posterior border; and the IGTV (Y-axis direction) was 7.31 mm for the upper boundary (head direction) and 10.16 mm for the lower boundary (feet direction). The motion of the GTV showed no significant correlation with the tidal volume of patients and the length of the tumor, but in relation to the tumor location, the displacement of the lower thoracic and the middle thoracic target volumes occurred in the direction of the anterior and right, which were not significantly different (T = 0.859, 0.229, P > 0.05) The significant differences were observed for the other directions (P < 0.05). Conclusions. - Because of respiratory and organ movements, the displacement of the tumor target volume was different in all directions. Therefore, we recommend that

Prediction of Marginal Mass Required for Successful Islet Transplantation

Science.gov (United States)

Papas, Klearchos K.; Colton, Clark K.; Qipo, Andi; Wu, Haiyan; Nelson, Rebecca A.; Hering, Bernhard J.; Weir, Gordon C.; Koulmanda, Maria

2013-01-01

Islet quality assessment methods for predicting diabetes reversal (DR) following transplantation are needed. We investigated two islet parameters, oxygen consumption rate (OCR) and OCR per DNA content, to predict transplantation outcome and explored the impact of islet quality on marginal islet mass for DR. Outcomes in immunosuppressed diabetic mice were evaluated by transplanting mixtures of healthy and purposely damaged rat islets for systematic variation of OCR/DNA over a wide range. The probability of DR increased with increasing transplanted OCR and OCR/DNA. On coordinates of OCR versus OCR/DNA, data fell into regions in which DR occurred in all, some, or none of the animals with a sharp threshold of around 150-nmol/min mg DNA. A model incorporating both parameters predicted transplantation outcome with sensitivity and specificity of 93% and 94%, respectively. Marginal mass was not constant, depended on OCR/DNA, and increased from 2,800 to over 100,000 islet equivalents/kg body weight as OCR/DNA decreased. We conclude that measurements of OCR and OCR/DNA are useful for predicting transplantation outcome in this model system, and OCR/DNA can be used to estimate the marginal mass required for reversing diabetes. Because human clinical islet preparations in a previous study had OCR/DNA values in the range of 100–150-nmol/min mg DNA, our findings suggest that substantial improvement in transplantation outcome may accompany increasedOCR/DNAin clinical islet preparations. PMID:20233002

Daily targeting of intrahepatic tumors for radiotherapy

International Nuclear Information System (INIS)

Balter, James M.; Brock, Kristy K.; Litzenberg, Dale W.; McShan, Daniel L.; Lawrence, Theodore S.; Haken, Randall Ten; McGinn, Cornelius J.; Lam, Kwok L.; Dawson, Laura A.

2002-01-01

Introduction: A system has been developed for daily targeting of intrahepatic tumors using a combination of ventilatory immobilization, in-room diagnostic imaging, and on-line setup adjustment. By reducing geometric position uncertainty, as well as organ movement, this system permits reduction of margins and thus potentially higher treatment doses. This paper reports our initial experience treating 8 patients with focal liver tumors using this system. Methods and Materials: The system includes diagnostic X-ray tubes mounted on the wall and ceiling of a treatment room, an active matrix flat panel imager, in-room control for image acquisition and setup adjustment, and a ventilatory immobilization system via active breathing control (ABC). Eight patients participated in the study, two using an early prototype ABC unit, and the remaining six with a commercial ABC system and improved setup measurement tools. Treatment margins were reduced, and dose consequently increased because of increased confidence in target position under this protocol. After daily setup via skin marks, orthogonal radiographs were acquired at suspended ventilation. The images were aligned to the CT model using the diaphragm for inferior-superior (IS) alignment, and the skeleton for left-right (LR) and anterior-posterior (AP) alignment. Adjustments were made for positioning errors greater than a threshold (3 or 5 mm). After treatment, retrospective analysis determined the final setup accuracy, as well as the error in initial setup measurement performed before setup adjustment. Results: Two hundred sixty-two treatment fractions were delivered on eight patients, with 171 treatments requiring repositioning. Typical treatment times were 25-30 min. Patients were able to tolerate ABC throughout the course of treatment. Breath holds up to 35 s long were used for treatment. The use of on-line imaging and setup adjustment reduced setup errors (σ) from 4.0 mm (LR), 6.7 mm (IS), and 3.8 mm (AP) to 2.1 mm (LR

Optimizing Collimator Margins for Isotoxically Dose-Escalated Conformal Radiation Therapy of Non-Small Cell Lung Cancer

Energy Technology Data Exchange (ETDEWEB)

Warren, Samantha, E-mail: Samantha.warren@oncology.ox.ac.uk [Department of Oncology, Gray Institute of Radiation Oncology and Biology, University of Oxford, Oxford (United Kingdom); Oxford Cancer Centre, Oxford University Hospitals, Oxford (United Kingdom); Panettieri, Vanessa [William Buckland Radiotherapy Centre, Alfred Hospital, Commercial Road, Melbourne (Australia); Panakis, Niki; Bates, Nicholas [Oxford Cancer Centre, Oxford University Hospitals, Oxford (United Kingdom); Lester, Jason F. [Velindre Cancer Centre, Velindre Road, Whitchurch, Cardiff (United Kingdom); Jain, Pooja [Clatterbridge Cancer Centre, Clatterbridge Road, Wirral (United Kingdom); Landau, David B. [Department of Radiotherapy, Guy' s and St. Thomas' NHS Foundation Trust, London (United Kingdom); Nahum, Alan E.; Mayles, W. Philip M. [Clatterbridge Cancer Centre, Clatterbridge Road, Wirral (United Kingdom); Fenwick, John D. [Department of Oncology, Gray Institute of Radiation Oncology and Biology, University of Oxford, Oxford (United Kingdom); Oxford Cancer Centre, Oxford University Hospitals, Oxford (United Kingdom)

2014-04-01

Purpose: Isotoxic dose escalation schedules such as IDEAL-CRT [isotoxic dose escalation and acceleration in lung cancer chemoradiation therapy] (ISRCTN12155469) individualize doses prescribed to lung tumors, generating a fixed modeled risk of radiation pneumonitis. Because the beam penumbra is broadened in lung, the choice of collimator margin is an important element of the optimization of isotoxic conformal radiation therapy for lung cancer. Methods and Materials: Twelve patients with stage I-III non-small cell lung cancer (NSCLC) were replanned retrospectively using a range of collimator margins. For each plan, the prescribed dose was calculated according to the IDEAL-CRT isotoxic prescription method, and the absolute dose (D{sub 99}) delivered to 99% of the planning target volume (PTV) was determined. Results: Reducing the multileaf collimator margin from the widely used 7 mm to a value of 2 mm produced gains of 2.1 to 15.6 Gy in absolute PTV D{sub 99}, with a mean gain ± 1 standard error of the mean of 6.2 ± 1.1 Gy (2-sided P<.001). Conclusions: For NSCLC patients treated with conformal radiation therapy and an isotoxic dose prescription, absolute doses in the PTV may be increased by using smaller collimator margins, reductions in relative coverage being offset by increases in prescribed dose.

Radiotherapy beyond cancer: Target localization in real-time MRI and treatment planning for cardiac radiosurgery

International Nuclear Information System (INIS)

Ipsen, S.; Blanck, O.; Rades, D.; Oborn, B.; Bode, F.; Liney, G.; Hunold, P.; Schweikard, A.; Keall, P. J.

2014-01-01

Purpose: Atrial fibrillation (AFib) is the most common cardiac arrhythmia that affects millions of patients world-wide. AFib is usually treated with minimally invasive, time consuming catheter ablation techniques. While recently noninvasive radiosurgery to the pulmonary vein antrum (PVA) in the left atrium has been proposed for AFib treatment, precise target location during treatment is challenging due to complex respiratory and cardiac motion. A MRI linear accelerator (MRI-Linac) could solve the problems of motion tracking and compensation using real-time image guidance. In this study, the authors quantified target motion ranges on cardiac magnetic resonance imaging (MRI) and analyzed the dosimetric benefits of margin reduction assuming real-time motion compensation was applied. Methods: For the imaging study, six human subjects underwent real-time cardiac MRI under free breathing. The target motion was analyzed retrospectively using a template matching algorithm. The planning study was conducted on a CT of an AFib patient with a centrally located esophagus undergoing catheter ablation, representing an ideal case for cardiac radiosurgery. The target definition was similar to the ablation lesions at the PVA created during catheter treatment. Safety margins of 0 mm (perfect tracking) to 8 mm (untracked respiratory motion) were added to the target, defining the planning target volume (PTV). For each margin, a 30 Gy single fraction IMRT plan was generated. Additionally, the influence of 1 and 3 T magnetic fields on the treatment beam delivery was simulated using Monte Carlo calculations to determine the dosimetric impact of MRI guidance for two different Linac positions. Results: Real-time cardiac MRI showed mean respiratory target motion of 10.2 mm (superior–inferior), 2.4 mm (anterior–posterior), and 2 mm (left–right). The planning study showed that increasing safety margins to encompass untracked respiratory motion leads to overlapping structures even in the

Radiotherapy beyond cancer: Target localization in real-time MRI and treatment planning for cardiac radiosurgery

Energy Technology Data Exchange (ETDEWEB)

Ipsen, S. [Radiation Physics Laboratory, Sydney Medical School, The University of Sydney, Sydney, New South Wales 2006, Australia and Institute for Robotics and Cognitive Systems, University of Luebeck, Luebeck 23562 (Germany); Blanck, O.; Rades, D. [Department of Radiation Oncology, University of Luebeck and University Medical Center Schleswig-Holstein, Campus Luebeck, Luebeck 23562 (Germany); Oborn, B. [Illawarra Cancer Care Centre (ICCC), Wollongong, New South Wales 2500, Australia and Centre for Medical Radiation Physics (CMRP), University of Wollongong, Wollongong, New South Wales 2500 (Australia); Bode, F. [Medical Department II, University of Luebeck and University Medical Center Schleswig-Holstein, Campus Luebeck, Luebeck 23562 (Germany); Liney, G. [Ingham Institute for Applied Medical Research, Liverpool Hospital, Liverpool, New South Wales 2170 (Australia); Hunold, P. [Department of Radiology and Nuclear Medicine, University of Luebeck and University Medical Center Schleswig-Holstein, Campus Luebeck, Luebeck 23562 (Germany); Schweikard, A. [Institute for Robotics and Cognitive Systems, University of Luebeck, Luebeck 23562 (Germany); Keall, P. J., E-mail: paul.keall@sydney.edu.au [Radiation Physics Laboratory, Sydney Medical School, The University of Sydney, Sydney, New South Wales 2006 (Australia)

2014-12-15

Purpose: Atrial fibrillation (AFib) is the most common cardiac arrhythmia that affects millions of patients world-wide. AFib is usually treated with minimally invasive, time consuming catheter ablation techniques. While recently noninvasive radiosurgery to the pulmonary vein antrum (PVA) in the left atrium has been proposed for AFib treatment, precise target location during treatment is challenging due to complex respiratory and cardiac motion. A MRI linear accelerator (MRI-Linac) could solve the problems of motion tracking and compensation using real-time image guidance. In this study, the authors quantified target motion ranges on cardiac magnetic resonance imaging (MRI) and analyzed the dosimetric benefits of margin reduction assuming real-time motion compensation was applied. Methods: For the imaging study, six human subjects underwent real-time cardiac MRI under free breathing. The target motion was analyzed retrospectively using a template matching algorithm. The planning study was conducted on a CT of an AFib patient with a centrally located esophagus undergoing catheter ablation, representing an ideal case for cardiac radiosurgery. The target definition was similar to the ablation lesions at the PVA created during catheter treatment. Safety margins of 0 mm (perfect tracking) to 8 mm (untracked respiratory motion) were added to the target, defining the planning target volume (PTV). For each margin, a 30 Gy single fraction IMRT plan was generated. Additionally, the influence of 1 and 3 T magnetic fields on the treatment beam delivery was simulated using Monte Carlo calculations to determine the dosimetric impact of MRI guidance for two different Linac positions. Results: Real-time cardiac MRI showed mean respiratory target motion of 10.2 mm (superior–inferior), 2.4 mm (anterior–posterior), and 2 mm (left–right). The planning study showed that increasing safety margins to encompass untracked respiratory motion leads to overlapping structures even in the

Radiotherapy beyond cancer: target localization in real-time MRI and treatment planning for cardiac radiosurgery.

Science.gov (United States)

Ipsen, S; Blanck, O; Oborn, B; Bode, F; Liney, G; Hunold, P; Rades, D; Schweikard, A; Keall, P J

2014-12-01

Atrial fibrillation (AFib) is the most common cardiac arrhythmia that affects millions of patients world-wide. AFib is usually treated with minimally invasive, time consuming catheter ablation techniques. While recently noninvasive radiosurgery to the pulmonary vein antrum (PVA) in the left atrium has been proposed for AFib treatment, precise target location during treatment is challenging due to complex respiratory and cardiac motion. A MRI linear accelerator (MRI-Linac) could solve the problems of motion tracking and compensation using real-time image guidance. In this study, the authors quantified target motion ranges on cardiac magnetic resonance imaging (MRI) and analyzed the dosimetric benefits of margin reduction assuming real-time motion compensation was applied. For the imaging study, six human subjects underwent real-time cardiac MRI under free breathing. The target motion was analyzed retrospectively using a template matching algorithm. The planning study was conducted on a CT of an AFib patient with a centrally located esophagus undergoing catheter ablation, representing an ideal case for cardiac radiosurgery. The target definition was similar to the ablation lesions at the PVA created during catheter treatment. Safety margins of 0 mm (perfect tracking) to 8 mm (untracked respiratory motion) were added to the target, defining the planning target volume (PTV). For each margin, a 30 Gy single fraction IMRT plan was generated. Additionally, the influence of 1 and 3 T magnetic fields on the treatment beam delivery was simulated using Monte Carlo calculations to determine the dosimetric impact of MRI guidance for two different Linac positions. Real-time cardiac MRI showed mean respiratory target motion of 10.2 mm (superior-inferior), 2.4 mm (anterior-posterior), and 2 mm (left-right). The planning study showed that increasing safety margins to encompass untracked respiratory motion leads to overlapping structures even in the ideal scenario, compromising

Effect of posterior crown margin placement on gingival health.

Science.gov (United States)

Reitemeier, Bernd; Hänsel, Kristina; Walter, Michael H; Kastner, Christian; Toutenburg, Helge

2002-02-01

The clinical impact of posterior crown margin placement on gingival health has not been thoroughly quantified. This study evaluated the effect of posterior crown margin placement with multivariate analysis. Ten general dentists reviewed 240 patients with 480 metal-ceramic crowns in a prospective clinical trial. The alloy was randomly selected from 2 high gold, 1 low gold, and 1 palladium alloy. Variables were the alloy used, oral hygiene index score before treatment, location of crown margins at baseline, and plaque index and sulcus bleeding index scores recorded for restored and control teeth after 1 year. The effect of crown margin placement on sulcular bleeding and plaque accumulation was analyzed with regression models (Prisk of bleeding at intrasulcular posterior crown margins was approximately twice that at supragingival margins. Poor oral hygiene before treatment and plaque also were associated with sulcular bleeding. Facial sites exhibited a lower probability of sulcular bleeding than lingual surfaces. Type of alloy did not influence sulcular bleeding. In this study, placement of crown margins was one of several parameters that affected gingival health.

Retail margins and the effects of an integrated Nordic end user market for electricity

Energy Technology Data Exchange (ETDEWEB)

Damsgaard, Niclas; Roempoetti, Marie

2007-09-15

impact of these effects on the customers' total price has not been assessed. Furthermore, it is possible that the customers can gain from receiving offers that are more adapted to their needs since a larger market provides better possibilities for market segmentation. The starting point for this project is an assumption that the customers can gain from a common Nordic market through reduced prices (or reduced margins). The question is thus: Can we expect that an integrated Nordic retail market for electricity will decrease the retail margins? In order to answer this question we study the existing retail margins and try to explain the differences in margins. We then analyse and assess whether an integrated Nordic market is likely to affect these margins. The main assumption is than that the reduced margins would come from an increased competitive pressure. In addition to reduced margins, there are several other possible benefits for the customers, e.g. improved competition and services, reduced costs, improvements in regulations and a better functioning wholesale market. This is discussed qualitatively in an adjacent report (Elforsk report 07:48). We find that it is not likely that an integrated Nordic retail market will increase the competitive pressure and in that way substantially reduce the retail margins. There might be some possibilities for reduced margins, at least in some countries and for some customer segments but the margins are generally relatively small. More importantly, the national retail markets are not very concentrated and a Nordic retail market will not dilute market power in the same way as is the case for the wholesale market. The price benefits for the customers can thus be expected to be modest. This conclusion does however not imply that our recommendation is not to pursue an integrated Nordic end-user market for electricity, but only that reduced retail margins probably is not a particularly strong argument for this

Colorado Basin Structure and Rifting, Argentine passive margin

Science.gov (United States)

Autin, Julia; Scheck-Wenderoth, Magdalena; Loegering, Markus; Anka, Zahie; Vallejo, Eduardo; Rodriguez, Jorge; Marchal, Denis; Reichert, Christian; di Primio, Rolando

2010-05-01

The Argentine margin presents a strong segmentation with considerable strike-slip movements along the fracture zones. We focus on the volcanic segment (between the Salado and Colorado transfer zones), which is characterized by seaward dipping reflectors (SDR) all along the ocean-continent transition [e.g. Franke et al., 2006; Gladczenko et al., 1997; Hinz et al., 1999]. The segment is structured by E-W trending basins, which differs from the South African margin basins and cannot be explained by classical models of rifting. Thus the study of the relationship between the basins and the Argentine margin itself will allow the understanding of their contemporary development. Moreover the comparison of the conjugate margins suggests a particular evolution of rifting and break-up. We firstly focus on the Colorado Basin, which is thought to be the conjugate of the well studied Orange Basin [Hirsch et al., 2009] at the South African margin [e.g. Franke et al., 2006]. This work presents results of a combined approach using seismic interpretation and structural, isostatic and thermal modelling highlighting the structure of the crust. The seismic interpretation shows two rift-related discordances: one intra syn-rift and the break-up unconformity. The overlying sediments of the sag phase are less deformed (no sedimentary wedges) and accumulated before the generation of oceanic crust. The axis of the Colorado Basin trends E-W in the western part, where the deepest pre-rift series are preserved. In contrast, the basin axis turns to a NW-SE direction in its eastern part, where mainly post-rift sediments accumulated. The most distal part reaches the margin slope and opens into the oceanic basin. The general basin direction is almost orthogonal to the present-day margin trend. The most frequent hypothesis explaining this geometry is that the Colorado Basin is an aborted rift resulting from a previous RRR triple junction [e.g. Franke et al., 2002]. The structural interpretation

Safety margins of operating reactors. Analysis of uncertainties and implications for decision making

International Nuclear Information System (INIS)

2003-01-01

Maintaining safety in the design and operation of nuclear power plants (NPPs) is a very important task under the conditions of a challenging environment, affected by the deregulated electricity market and implementation of risk informed regulations. In Member States, advanced computer codes are widely used as safety analysis tools in the framework of licensing of new NPP projects, safety upgrading programmes of existing NPPs, periodic safety reviews, renewal of operating licences, use of the safety margins for reactor power uprating, better utilization of nuclear fuel and higher operational flexibility, for justification of lifetime extensions, development of new emergency operating procedures, analysis of operational events, and development of accident management programmes. The issue of inadequate quality of safety analysis is becoming important due to a general tendency to use advanced tools for better establishment and utilization of safety margins, while the existence of such margins assure that NPPs operate safely in all modes of operation and at all times. The most important safety margins relate to physical barriers against release of radioactive material, such as fuel matrix and fuel cladding, reactor coolant system boundary, and the containment. Typically, safety margins are determined with use of computational tools for safety analysis. Advanced best estimate computer codes are suggested e.g. in the IAEA Safety Guide on Safety Assessment and Verification for Nuclear Power Plants to be used for current safety analysis. Such computer codes require their careful application to avoid unjustified reduction in robustness of the reactor safety. The issue of uncertainties in safety analyses and their impact on evaluation of safety margins is addressed in a number of IAEA guidance documents, in particular in the Safety Report on Accident Analysis for Nuclear Power Plants. It is also discussed in various technical meetings and workshops devoted to this area. The

Histopathological Validation of the Surface-Intermediate-Base Margin Score for Standardized Reporting of Resection Technique during Nephron Sparing Surgery.

Science.gov (United States)

Minervini, Andrea; Campi, Riccardo; Kutikov, Alexander; Montagnani, Ilaria; Sessa, Francesco; Serni, Sergio; Raspollini, Maria Rosaria; Carini, Marco

2015-10-01

The surface-intermediate-base margin score is a novel standardized reporting system of resection techniques during nephron sparing surgery. We validated the surgeon assessed surface-intermediate-base score with microscopic histopathological assessment of partial nephrectomy specimens. Between June and August 2014 data were prospectively collected from 40 consecutive patients undergoing nephron sparing surgery. The surface-intermediate-base score was assigned to all cases. The score specific areas were color coded with tissue margin ink and sectioned for histological evaluation of healthy renal margin thickness. Maximum, minimum and mean thickness of healthy renal margin for each score specific area grade (surface [S] = 0, S = 1 ; intermediate [I] or base [B] = 0, I or B = 1, I or B = 2) was reported. The Mann-Whitney U and Kruskal-Wallis tests were used to compare the thickness of healthy renal margin in S = 0 vs 1 and I or B = 0 vs 1 vs 2 grades, respectively. Maximum, minimum and mean thickness of healthy renal margin was significantly different among score specific area grades S = 0 vs 1, and I or B = 0 vs 1, 0 vs 2 and 1 vs 2 (p <0.001). The main limitations of the study are the low number of the I or B = 1 and I or B = 2 samples and the assumption that each microscopic slide reflects the entire score specific area for histological analysis. The surface-intermediate-base scoring method can be readily harnessed in real-world clinical practice and accurately mirrors histopathological analysis for quantification and reporting of healthy renal margin thickness removed during tumor excision. Copyright © 2015 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Deep inspiration breath-hold technique for lung tumors: the potential value of target immobilization and reduced lung density in dose escalation

International Nuclear Information System (INIS)

Hanley, J.; Debois, M.M.; Raben, A.; Mageras, G.S.; Lutz, W.R.; Mychalczak, B.; Schwartz, L.H.; Gloeggler, P.J.; Leibel, S.A.; Fuks, Z.; Kutcher, G.J.

1996-01-01

compared to assess the improvement due to target immobilization and reduced lung density. To estimate the role of target immobilization alone, an additional plan is generated using the DIBH PTV, but with the assumption it is surrounded by free-breathing, not deep inspiration, density lung. Results: The results of the study suggest that the DIBH technique can reduce the mass of lung irradiated to high dose, so that the possibility for dose escalation is increased. The relative contribution of reduced lung density and reduced margin for motion vary depending on the tumor size, level of DIBH and extent of tumor motion in free-breathing. An example treatment plan comparison for a typical patient is shown in the figure, which is a cumulative dose mass histogram (DMH) depicting the mass of normal lung tissue receiving at least a certain dose. The lung DMHs shown are for three plans: (A) Free-breathing; (B) Target immobilization only; (C) Target immobilization plus reduced lung density. It is observed that the mass of lung tissue treated to high doses is less for cases B and C. For example, the mass receiving >24.5 Gy is 235 g for free-breathing (A), 180 g for immobilization alone (B) and 150 g for DIBH (C). For this patient, target immobilization alone would allow a dose escalation from 75.6 Gy to 95 Gy for the same level of NTCP as the free-breathing plan, the added effect of reduced density would then enable a further escalation from 95 Gy to 110 Gy. For this study, the measured tumor motions ranged from 5 to 12 mm for free-breathing and 1 to 3 mm for DIBH. For the example shown in the figure the tumor motion was 10 mm and DIBH reproducibility was 3 mm. Additional details on the DIBH technique and results for a group of patients will be presented. Conclusions: Compared to conventional free-breathing treatment the DIBH technique benefits from reduced margins, as a result of the suppressed target motion, as well as a decreased lung density - both contribute to moving normal lung

The Seismicity of Two Hyperextended Margins

Science.gov (United States)

Redfield, Tim; Terje Osmundsen, Per

2013-04-01

A seismic belt marks the outermost edge of Scandinavia's proximal margin, inboard of and roughly parallel to the Taper Break. A similar near- to onshore seismic belt runs along its inner edge, roughly parallel to and outboard of the asymmetric, seaward-facing escarpment. The belts converge at both the northern and southern ends of Scandinavia, where crustal taper is sharp and the proximal margin is narrow. Very few seismic events have been recorded on the intervening, gently-tapering Trøndelag Platform. Norway's distribution of seismicity is systematically ordered with respect to 1) the structural templates of high-beta extension that shaped the thinning gradient during Late Jurassic or Early Cretaceous time, and 2) the topographically resurgent Cretaceous-Cenozoic "accommodation phase" family of escarpments that approximate the innermost limit of crustal thinning [See Redfield and Osmundsen (2012) for diagrams, definitions, discussion, and supporting citations.] Landwards from the belt of earthquake epicenters that mark the Taper Break the crust consistently thickens, and large fault arrays tend to sole out at mid crustal levels. Towards the sea the crystalline continental crust is hyperextended, pervasively faulted, and generally very thin. Also, faulting and serpentinization may have affected the uppermost parts of the distal margin's lithospheric mantle. Such contrasting structural conditions may generate a contrasting stiffness: for a given stress, more strain can be accommodated in the distal margin than in the less faulted proximal margin. By way of comparison, inboard of the Taper Break on the gently-tapered Trøndelag Platform, faulting was not penetrative. There, similar structural conditions prevail and proximal margin seismicity is negligible. Because stress concentration can occur where material properties undergo significant contrast, the necking zone may constitute a natural localization point for post-thinning phase earthquakes. In Scandinavia

The Marginal Source of Finance

OpenAIRE

Lindhe, Tobias

2002-01-01

This paper addresses the ongoingdebate on which view of equity, traditional or new, that best describes firm behavior. According to the traditional view, the marginal source of finance is new equity, whereas under to the new view, marginal financing comes from retained earnings. In the theoretical part, we set up a model where the firm faces a cost of adjusting the dividend level because of an aggravated free cash flow problem. The existence of such a cost - which has been used in arguing the...

Negative predictive value of ultrasound in predicting tumor-free margins in specimen sonography

International Nuclear Information System (INIS)

Naz, S.; Hafeez, S.; Hussain, Z.; Hilal, K.

2017-01-01

Objective: To evaluate the success of ultrasound in post-excision specimen visualization, and negative predictive value of ultrasound for estimation of tumor-free margins using histopathology as the gold standard. Study Design: Cross-sectional analytical study. Place and Duration of Study: The Aga Khan University Hospital, Karachi, Pakistan, from May 2010 till January 2013. Methodology: Sonography of all breast nodules was done before and after exicision by two female radiologists with at least five years clinical experience. All surgeries were performed by the same referring breast surgeons. All nodules were non-palpable and had histopathology as well as specimen sonography performed at AKUH. Subjects were excluded, if histopathology was not available, post-procedure sonogram not done or done in another hospital and nodules that were not seen on ultrasound. After needle localization in 47 patients using ultrasound and in 7 patients using mammogram was done, sonogram was conducted in all 54 lesions. These were then assessed by ultrasound for detection of lesion and tumor-free margins in malignant lesion. Post-excision ultrasound was performed for the evaluation of lesion whether visualized or absent with localizing needle in situ, lesion dimensions, depth measurement between the superior margin of the lesion and its edge. Results: All 54 lesions were present on post-exicison scan, out of which 28 were documented as malignant and 26 as benign. Ultrasound declared all specimens as tumor-free. On histopathology, two lesions were documented as having tumor-positive margins and were proven to be invasive lobular carcinoma. Therefore, the negative predictive value of the specimen sonography for margin detection was 26/28 (92.8%). Conclusion: Ultrasound of the excised breast tumor specimen is a simple and reliable technique for confirmation of the tumor-free margins in non-palpable breast lesions. (author)

Quantifying the margin sharpness of lesions on radiological images for content-based image retrieval

International Nuclear Information System (INIS)

Xu Jiajing; Napel, Sandy; Greenspan, Hayit; Beaulieu, Christopher F.; Agrawal, Neeraj; Rubin, Daniel

2012-01-01

. Equivalence across deformations was assessed using Schuirmann's paired two one-sided tests. Results: In simulated images, the concordance correlation between measured gradient and actual gradient was 0.994. The mean (s.d.) and standard deviation NDCG score for the retrieval of K images, K = 5, 10, and 15, were 84% (8%), 85% (7%), and 85% (7%) for CT images containing liver lesions, and 82% (7%), 84% (6%), and 85% (4%) for CT images containing lung nodules, respectively. The authors’ proposed method outperformed the two existing margin characterization methods in average NDCG scores over all K, by 1.5% and 3% in datasets containing liver lesion, and 4.5% and 5% in datasets containing lung nodules. Equivalence testing showed that the authors’ feature is more robust across all margin deformations (p < 0.05) than the two existing methods for margin sharpness characterization in both simulated and clinical datasets. Conclusions: The authors have described a new image feature to quantify the margin sharpness of lesions. It has strong correlation with known margin sharpness in simulated images and in clinical CT images containing liver lesions and lung nodules. This image feature has excellent performance for retrieving images with similar margin characteristics, suggesting potential utility, in conjunction with other lesion features, for content-based image retrieval applications.

The use of active breathing control (ABC) to reduce margin for breathing motion

International Nuclear Information System (INIS)

Wong, John W.; Sharpe, Michael B.; Jaffray, David A.; Kini, Vijay R.; Robertson, John M.; Stromberg, Jannifer S.; Martinez, Alavro A.

1999-01-01

. The variation of the organ positions and volumes for the different scans were quantified and compared. Results: The ABC procedure was well tolerated in the 12 patients. When ABC was applied near the end of normal expiration, the minimal duration of active breath-hold was 15 s for 1 patient with lung cancer, and 20 s or more for all other patients. The duration was greater than 40 s for 2 patients with Hodgkin's disease when ABC was applied during deep inspiration. Scan artifacts associated with normal breathing motion were not observed in the ABC scans. The analysis of the small set of intrafraction scan data indicated that with ABC, the liver volumes were reproducible at about 1%, and lung volumes to within 6%. The excursions of a 'center of target' parameter for the livers were less than 1 mm at the same respiratory phase, but were larger than 4 mm at the extremes of the breathing cycle. The inter-fraction scan study indicated that daily setup variation contributed to the uncertainty in assessing the reproducibility of organ immobilization with ABC between treatment fractions. Conclusion: The results were encouraging; ABC provides a simple means to minimize breathing motion. When applied for CT scanning and treatment, the ABC procedure requires no more than standard operation of the CT scanner or the medical accelerator. The ABC scans are void of motion artifacts commonly seen on fast spiral CT scans. When acquired at different points in the breathing cycle, these ABC scans show organ motion in three-dimension (3D) that can be used to enhance treatment planning. Reproducibility of organ immobilization with ABC throughout the course of treatment must be quantified before the procedure can be applied to reduce margin for conformal treatment

The availability and economic analyses of using marginal land for bioenergy production in China

Science.gov (United States)

Yuqi, Chen; Xudong, Guo; Chunyan, Lv

2017-04-01

In recent years, China has witnessed rapid increase in the dependence of foreign oil import. In 2015, the primary energy consumption of China is 543 million tons, of which 328 million tons was imported. The total amount of imported foreign oil increased from 49.8% in 2008 to 60.41% in 2016. To address the national energy security and GHG emission reduction, China has made considerable progress in expanding renewable energy portfolio, especially liquid biofuels. However, under the pressure of high population and vulnerable food security, China's National Development and Reform Commission (NDRC) ruled that bioenergy is only allowed to be produced using non-cereal feedstock. In addition, the energy crops can only be planted on marginal land, which is the land not suitable for growing field crops due to edaphic and/or climatic limitations, and other environmental risks. Although there have been a number of studies about estimating the marginal land for energy plants' cultivation in China, as to the different definition of marginal land and land use data, the results are quite different. Furthermore, even if there is enough marginal land suitable for energy plants' cultivation, economic viability of cultivating energy plants on marginal land is critical. In order to analyze the availability and economic analyses of the marginal land for bioenergy production strategy, firstly, by using of the latest and most authoritative land use data, this study focused on the assessment of marginal land resources and bioenergy potential by planting five species of energy plants including Cassava, Jatropha curcas, Helianthus tuberous L, Pistacia chinensis, Xanthoceras sorbifolia Bunge. The results indicate that there are 289.71 million ha marginal land can be used for these five energy plants' cultivation, which can produce 24.45 million tons bioethanol and 8.77 million tons of biodiesel. Secondly, based on field survey data and literature reviews, we found that, from the farmers

Biosafety research for non-target organism risk assessment of RNAi-based GE plants

Science.gov (United States)

Roberts, Andrew F.; Devos, Yann; Lemgo, Godwin N. Y.; Zhou, Xuguo

2015-01-01

RNA interference, or RNAi, refers to a set of biological processes that make use of conserved cellular machinery to silence genes. Although there are several variations in the source and mechanism, they are all triggered by double stranded RNA (dsRNA) which is processed by a protein complex into small, single stranded RNA, referred to as small interfering RNAs (siRNA) with complementarity to sequences in genes targeted for silencing. The use of the RNAi mechanism to develop new traits in plants has fueled a discussion about the environmental safety of the technology for these applications, and this was the subject of a symposium session at the 13th ISBGMO in Cape Town, South Africa. This paper continues that discussion by proposing research areas that may be beneficial for future environmental risk assessments of RNAi-based genetically modified plants, with a particular focus on non-target organism assessment. PMID:26594220

Tumor-related markers in histologically normal margins correlate with locally recurrent oral squamous cell carcinoma: a retrospective study.

Science.gov (United States)

Wang, Xinhong; Chen, Si; Chen, Xinming; Zhang, Cuicui; Liang, Xueyi

2016-02-01

Oral squamous cell carcinoma (OSCC) is characterized by a high rate of local recurrence (LR) even when the surgical margins are considered histopathologically 'normal'. The aim of our study was to determine the relationship between early tumor-related markers detected in histologically normal margins (HNM) and LR as well as disease-free survival in OSCC. The loss of heterozygosity (LOH) of markers on 9p21 (D9s1747, RPS6, D9s162) and 17p13 (TP53) and the immunostaining results of the corresponding mutant P53, P14, P15, and P16 proteins were assessed and correlated with LR and disease-free survival in 71 OSCC patients who had HNM. Fifteen of 71 patients with HNM developed LR. The presence of the following molecular markers in surgical margins was significantly correlated with the development of LR: LOH on chromosome 9p21 (D9s1747 + RPS6 + D9s162), any LOH, P16, and P53 (chi-square test, P tumor-related markers in histologically 'normal' resection margins may be a useful method for assessing LR in OSCC patients. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Risk factors for and consequences of inadequate surgical margins in oral squamous cell carcinoma

DEFF Research Database (Denmark)

Lawaetz, Mads; Homøe, Preben

2014-01-01

OBJECTIVE: The purpose of this study was to examine which factors are associated with inadequate surgical margins and to assess the postoperative consequences. STUDY DESIGN: A retrospective cohort of 110 patients with oral squamous cell carcinoma treated with surgery during a 2-year period...

Feasibility of Using the Marginal Blood Vessels as Reference Landmarks for CT Colonography

Science.gov (United States)

Wei, Zhuoshi; Yao, Jianhua; Wang, Shijun; Liu, Jiamin; Dwyer, Andrew J.; Pickhardt, Perry J.; Nowinski, Wieslaw L.; Summers, Ronald M.

2015-01-01

OBJECTIVE The purpose of this study was to show the spatial relationship of the colonic marginal blood vessels and the teniae coli on CT colonography (CTC) and the use of the marginal blood vessels for supine-prone registration of polyps and for determination of proper connectivity of collapsed colonic segments. MATERIALS AND METHODS We manually labeled the marginal blood vessels on 15 CTC examinations. Colon segmentation, centerline extraction, teniae detection, and teniae identification were automatically performed. For assessment of their spatial relationships, the distances from the marginal blood vessels to the three teniae coli and to the colon were measured. Student t tests (paired, two-tailed) were performed to evaluate the differences among these distances. To evaluate the reliability of the marginal vessels as reference points for polyp correlation, we analyzed 20 polyps from 20 additional patients who underwent supine and prone CTC. The average difference of the circumferential polyp position on the supine and prone scans was computed. Student t tests (paired, two-tailed) were performed to evaluate the supine-prone differences of the distance. We performed a study on 10 CTC studies from 10 patients with collapsed colonic segments by manually tracing the marginal blood vessels near the collapsed regions to resolve the ambiguity of the colon path. RESULTS The average distances (± SD) from the marginal blood vessels to the tenia mesocolica, tenia omentalis, and tenia libera were 20.1 ± 3.1 mm (95% CI, 18.5–21.6 mm), 39.5 ± 4.8 mm (37.1–42.0 mm), and 36.9 ± 4.2 mm (34.8–39.1 mm), respectively. Pairwise comparison showed that these distances to the tenia libera and tenia omentalis were significantly different from the distance to the tenia mesocolica (p marginal blood vessels to the colon wall was 15.3 ± 2.0 mm (14.2–16.3 mm). For polyp localization, the average difference of the circumferential polyp position on the supine and prone scans was 9

Influence of Different Implant Geometry in Clinical Longevity and Maintenance of Marginal Bone: A Systematic Review.

Science.gov (United States)

Lovatto, Sabrina Telles; Bassani, Rafaela; Sarkis-Onofre, Rafael; Dos Santos, Mateus Bertolini Fernandes

2018-03-26

To assess, through a systematic review, the influence of different implant geometries on clinical longevity and maintenance of marginal bone tissue. An electronic search was conducted in MEDLINE, Scopus, and Web of Science databases, limited to studies written in English from 1996 to 2017 using specific search strategies. Only randomized controlled trials (RCTs) that compared dental implants and their geometries were included. Two reviewers independently selected studies, extracted data, and assessed the risk of bias of included studies. From the 4006 references identified by the search, 24 were considered eligible for full-text analysis, after which 10 studies were included in this review. A similar behavior of marginal bone loss between tapered and cylindrical geometries was observed; however, implants that had micro-threads in the neck presented a slight decrease of marginal bone loss compared to implants with straight or smooth neck. Success and survival rates were high, with cylindrical implants presenting higher success and survival rates than tapered ones. Implant geometry seems to have little influence on marginal bone loss (MBL) and survival and success rates after 1 year of implant placement; however, the evidence in this systematic review was classified as very low due to limitations such as study design, sample size, and publication bias. Thus, more well-designed RCTs should be conducted to provide evidence regarding the influence of implant geometry on MBL and survival and success rates after 1 year of implant placement. © 2018 by the American College of Prosthodontists.

Additional safety assessments. Report by the Nuclear Safety Authority - December 2011

International Nuclear Information System (INIS)

2011-12-01

The first part of this voluminous report proposes an assessment of targeted audits performed in French nuclear installations (water pressurized reactors on the one hand, laboratories, factories and waste and dismantling installations on the other hand) on issues related to the Fukushima accident. The examined issues were the protection against flooding and against earthquake, and the loss of electricity supplies and of cooling sources. The second part addresses the additional safety assessments of the reactors and the European resistance tests: presentation of the French electronuclear stock, earthquake, flooding and natural hazards (installation sizing, safety margin assessment), loss of electricity supplies and cooling systems, management of severe accidents, subcontracting conditions. The third part addresses the same issues for nuclear installations other than nuclear power reactors

Time path of marginal cost for measures against global warming toward the greenhouse gas concentration target. Analytic solution and case study of the electric power sector; Onshitsu koka gas nodo mokuhyoka deno ondanka taisaku genkai hiyo no jikan keiro. Kaisekikai to denryoku bumon no case study

Energy Technology Data Exchange (ETDEWEB)

Nagano, K.; Sugiyama, H.; Takahashi, M. [Central Research Institute of Electric Power Industry, Tokyo (Japan)

1997-01-30

The United Nations Framework Convention on Climate Change is studied from the viewpoint of implementing costs. As far as the global warming issue is concerned, the factor to affect the environment is not the emitted volume but the concentration in the air. The ultimate target is the stabilization of greenhouse gas concentration at a level not to impose serious artificial damage on the ecosystem. Accordingly, various time paths are considered, including one in which much emission is allowed at the beginning and suppression is enforced acceleratedly in the later stage. In this study, a path demanding but the minimal cost in the period up to the target time point is discussed, using as the tool the marginal cost for measure implementation. In a reasonable emission control strategy, the emission control marginal cost follows a time path that is dependent upon an increase function to be determined by the discount rate and survival rate (time constant) in the atmosphere. In the industrial branch, instead of imposing short-term and rigid emission volume control limits, a longer-term target may be set for reduction in the loads responsible for concentration acceleration, concrete emission controls under the given conditions may be implemented at the discretion of the implementing organizations, and reduction in cost may be realized by time distribution with the environmental impacts kept at approximately equal levels. 5 refs., 2 figs., 3 tabs.

Can FDG-PET assist in radiotherapy target volume definition of metastatic lymph nodes in head-and-neck cancer?

International Nuclear Information System (INIS)

Schinagl, Dominic A.X.; Hoffmann, Aswin L.; Vogel, Wouter V.; Dalen, Jorn A. van; Verstappen, Suzan M.M.; Oyen, Wim J.G.; Kaanders, Johannes H.A.M.

2009-01-01

Background and purpose: The role of FDG-PET in radiotherapy target volume definition of the neck was evaluated by comparing eight methods of FDG-PET segmentation to the current CT-based practice of lymph node assessment in head-and-neck cancer patients. Materials and methods: Seventy-eight head-and-neck cancer patients underwent coregistered CT- and FDG-PET scans. Lymph nodes were classified as 'enlarged' if the shortest axial diameter on CT was ≥10 mm, and as 'marginally enlarged' if it was 7-10 mm. Subsequently, lymph nodes were assessed on FDG-PET applying eight segmentation methods: visual interpretation (PET VIS ), applying fixed thresholds at a standardized uptake value (SUV) of 2.5 and at 40% and 50% of the maximum signal intensity of the primary tumor (PET SUV , PET 40% , PET 50% ) and applying a variable threshold based on the signal-to-background ratio (PET SBR ). Finally, PET 40%N , PET 50%N and PET SBRN were acquired using the signal of the lymph node as the threshold reference. Results: Of 108 nodes classified as 'enlarged' on CT, 75% were also identified by PET VIS , 59% by PET 40% , 43% by PET 50% and 43% by PET SBR . Of 100 nodes classified as 'marginally enlarged', only a minority were visualized by FDG-PET. The respective numbers were 26%, 10%, 7% and 8% for PET VIS , PET 40% , PET 50% and PET SBR . PET 40%N , PET 50%N and PET SBRN , respectively, identified 66%, 82% and 96% of the PET VIS -positive nodes. Conclusions: Many lymph nodes that are enlarged and considered metastatic by standard CT-based criteria appear to be negative on FDG-PET scan. Alternately, a small proportion of marginally enlarged nodes are positive on FDG-PET scan. However, the results are largely dependent on the PET segmentation tool used, and until proper validation FDG-PET is not recommended for target volume definition of metastatic lymph nodes in routine practice.

Breast MR imaging for the assessment of residual disease following initial surgery for breast cancer with positive margins

Energy Technology Data Exchange (ETDEWEB)

Krammer, Julia [University Medical Center Mannheim, Medical Faculty Mannheim, University of Heidelberg, Institute of Clinical Radiology and Nuclear Medicine, Mannheim (Germany); Memorial Sloan-Kettering Cancer Center, Breast Imaging Section, Department of Radiology, New York, NY (United States); Price, Elissa R. [University of California, San Francisco, Department of Radiology and Biomedical Imaging, Division of Women' s Imaging, San Francisco, CA (United States); Jochelson, Maxine S.; Watson, Elizabeth; Morris, Elizabeth A. [Memorial Sloan-Kettering Cancer Center, Breast Imaging Section, Department of Radiology, New York, NY (United States); Murray, Melissa P. [Memorial Sloan-Kettering Cancer Center, Department of Pathology, New York, NY (United States); Schoenberg, Stefan O. [University Medical Center Mannheim, Medical Faculty Mannheim, University of Heidelberg, Institute of Clinical Radiology and Nuclear Medicine, Mannheim (Germany)

2017-11-15

To determine the accuracy of post-operative MR in predicting residual disease in women with positive margins, emphasizing the size thresholds at which residual disease can be confidently identified. This IRB-approved HIPAA-compliant retrospective study included 175 patients with MR after positive margins following initial surgery for breast cancer. Two expert readers independently re-evaluated MR images for evidence of residual disease at the surgical cavity and multifocal/multicentric disease. All patients underwent definitive surgery and MR findings were correlated to histopathology. 139/175 (79.4%) patients had residual disease at surgery. Average overall sensitivity, specificity, PPV and NPV for residual disease at the surgical cavity were 73%, 72%, 91% and 45%, respectively. The readers identified 42/45 (93%, reader 1) and 43/45 (95%, reader 2) patients with residual invasive disease at the cavity of ≥5 mm and 22/22 (100%, both readers) patients with disease ≥10 mm. Average sensitivity, specificity, PPV and NPV for unknown multifocal/multicentric disease were 90%, 96%, 93% and 86%, respectively. Post-operative breast MR can accurately depict ≥5-mm residual disease at the surgical cavity and unsuspected multifocal/multicentric disease. These findings have the potential to lead to more appropriate selection of second surgical procedures in women with positive margins. (orig.)