检索结果-内蒙古大学图书馆

A robust ranking algorithm to spamming

EPL 2011年第4期94卷

作者： Zhou, Yan-Bo Lei, Ting Zhou, Tao Univ Fribourg Dept Phys CH-1700 Fribourg Switzerland Univ Elect Sci & Technol China Web Sci Ctr Chengdu 610054 Peoples R China

Ranking problem of web-based rating systems has attracted much attention. A good ranking algorithm should be robust against spammer attack. Here we proposed a correlation-based reputation algorithm to solve the ranking problem of such rating systems where user votes some objects with ratings. In this algorithm, the reputation of a user is iteratively determined by the correlation coefficient between his/her rating vector and the corresponding objects' weighted average rating vector. Comparing with iterative refinement (IR) and mean score algorithm, results for both artificial and real data indicate that the present algorithm shows a higher robustness against spammer attack. Copyright (C) EPLA, 2011

关键词： computer science and technology Social and economic systems World Wide Web, Internet

来源：评论

学校读者我要写书评

暂无评论

Effective privacy amplification for secure classical communications

引用

EPL 2011年第2期94卷

作者： Horvath, T. Kish, L. B. Scheuer, J. Univ Bonn Dept Comp Sci D-5300 Bonn Germany Fraunhofer IAIS D-53754 Schloss Birlinghoven Sankt Augustin Germany Texas A&M Univ Dept Elect & Comp Engn College Stn TX 77843 USA Tel Aviv Univ Sch Elect Engn Ramat Aviv Israel Tel Aviv Univ Ctr Nanosci & Nanotechnol Ramat Aviv Israel

We study the practical effectiveness of privacy amplification for classical key distribution schemes. We find that in contrast to quantum key distribution schemes, the high fidelity of the raw key generated in classical systems allow the users to always sift a secure shorter key if they have an upper bound on the eavesdropper probability to correctly guess the exchanged key bits. The number of privacy amplification iterations needed to achieve information leak of 10(-8) in existing classical communicators is 2 or 3 resulting in a corresponding slowdown 4 to 8. We analyze the inherent tradeoff between the number of iterations and the security of the raw key. This property which is unique to classical key distribution systems render them highly useful for practical, especially for noisy channels where sufficiently low quantum bit error ratios are difficult to achieve. Copyright (C) EPLA, 2011

关键词： Other topics in areas of applied and interdisciplinary physics (restricted to new topics in section 89) computer science and technology

来源：评论

学校读者我要写书评

暂无评论

Enabling a high throughput real time data pipeline for a large radio telescope array with GPUs

引用

computer PHYSICS COMMUNICATIONS 2010年第10期181卷 1707-1714页

作者： Edgar, R. G. Clark, M. A. Dale, K. Mitchell, D. A. Ord, S. M. Wayth, R. B. Pfister, H. Greenhill, L. J. Initiat Innovat Comp Cambridge MA 02138 USA Harvard Smithsonian Ctr Astrophys Cambridge MA 02138 USA Sch Engn & Appl Sci Cambridge MA 02138 USA

The Murchison Widefield Array (MWA) is a next-generation radio telescope currently under construction in the remote Western Australia Outback. Raw data will be generated continuously at 5 GiBs(-1), grouped into 8 s cadences. This high throughput motivates the development of on-site, real time processing and reduction in preference to archiving, transport and off-line processing. Each batch of 8 s data must be completely reduced before the next batch arrives. Maintaining real time operation will require a sustained performance of around 2.5 TFLOPs(-1) (including convolutions, FFTs, interpolations and matrix multiplications). We describe a scalable heterogeneous computing pipeline implementation, exploiting both the high computing density and FLOP-per-Watt ratio of modern GPUs. The architecture is highly parallel within and across nodes, with all major processing elements performed by GPUs. Necessary scatter-gather operations along the pipeline are loosely synchronized between the nodes hosting the GPUs. The MWA will be a frontier scientific instrument and a pathfinder for planned peta- and exa-scale facilities. (c) 2010 Elsevier B.V. All rights reserved.

关键词： Radio telescopes and instrumentation Heterodyne receivers Mathematical procedures and computer techniques computer science and technology

来源：评论

学校读者我要写书评

暂无评论

Prose and Poetry Classification and Boundary Detection Using Word Adjacency Network Analysis

引用

INTERNATIONAL JOURNAL OF MODERN PHYSICS C 2010年第4期21卷 513-522页

作者： Mrowinski, Maciej J. Kosinski, Robert A. Warsaw Univ Technol Fac Phys PL-00662 Warsaw Poland Natl Res Inst Cent Inst Labour Protect PL-00701 Warsaw Poland

Word adjacency networks constructed from written works reflect differences in the structure of prose and poetry. We present a method to disambiguate prose and poetry by analyzing network parameters of word adjacency networks, such as the clustering coefficient, average path length and average degree. We determine the relevant parameters for disambiguation using linear discriminant analysis (LDA) and the effect size criterion. The accuracy of the method is 74.9 +/- 2.9% for the training set and 73.7 +/- 6.4% for the test set which are greater than the acceptable classifier requirement of 67.3%. This approach is also useful in locating text boundaries within a single article which falls within a window size where the significant change in clustering coefficient is observed. Results indicate that an optimal window size of 75 words can detect the text boundaries.

关键词： Text genre classification word adjacency networks LDA Structures and organization in complex systems Complex systems computer science and technology

来源：评论

学校读者我要写书评

暂无评论

Solving the cold-start problem in recommender systems with social tags

引用

EPL 2010年第2期92卷

作者： Zhang, Zi-Ke Liu, Chuang Zhang, Yi-Cheng Zhou, Tao Univ Elect Sci & Technol China Web Sci Ctr Chengdu 610054 Peoples R China Univ Fribourg Dept Phys CH-1700 Fribourg Switzerland E China Univ Sci & Technol Sch Business Shanghai 200237 Peoples R China E China Univ Sci & Technol Engn Res Ctr Proc Syst Engn Minist Educ Shanghai 200237 Peoples R China Univ Sci & Technol China Dept Modern Phys Hefei 230026 Peoples R China

Based on the user-tag-object tripartite graphs, we propose a recommendation algorithm that makes use of social tags. Besides its low cost of computational time, the experimental results on two real-world data sets, *** and MovieLens, show that it can enhance the algorithmic accuracy and diversity. Especially, it provides more personalized recommendation when the assigned tags belong to more diverse topics. The proposed algorithm is particularly effective for small-degree objects, which reminds us of the well-known cold-start problem in recommender systems. Further empirical study shows that the proposed algorithm can significantly solve this problem in social tagging systems with heterogeneous object degree. Copyright (C) EPLA, 2010

关键词： computer science and technology Networks and genealogical trees Social and economic systems

来源：评论

学校读者我要写书评

暂无评论

WE-C-BRB-09: Volumetric Modulated Arc Therapy Based Total Marrow Irradiation and Dosimetry Verification

引用

Medical Physics 2011年第6PART32期38卷 3806-3806页

作者： Y Liang L Mell G Kim Center for Advanced Radiotherapy Technologies University of California San Diego La Jolla CA University of California San Diego La Jolla CA

Purpose: This study develops treatment planning and a comprehensive dosimetry verification procedure for volumetric modulated arc therapy(VMAT) based total marrow irradiation(TMI), a form of targeted total body irradiation(TBI). Methods: The simulation CT of 3 patients treated with TBI were used. Planning was done with Eclipse treatment planning system(Varian Medical Systems, CA). Planning volume(PTV) was defined as skeletal bone, rib, and sternum, with 3mm margin, from head to mid-femur. In total marrow and lymphoid irradiation(TMLI), PTV is expanded to include spleen and major lymph nodes. The mandible, maxillary bones and forearms were excluded. The dose prescription was 12Gy in 6 fractions. The PTV is divided into head-and-neck(H&N), chest and pelvis regions. Correspondingly, there is separate plan for each region, composed of 2∼3 arcs/fields with multiple isocenters along patient axial direction. The 2D dosimetry verification was conducted with EBT2 Gafchromic film(International Specialty Products, NJ) for gamma evaluation and ion chamber for absolute point dose measurement, using a IMRT phantom(computerized Imaging Reference Systems, VA) and RIT software(Radiological Imaging technology, CO), with emphasis of junction area between neighboring plans for hot/cold spots. We further conduct volumetric dose verification with electronic portal imaging devices and DosimetryCheck program(Math resolutions, MD). The gamma evaluation criteria were 5% absolute point dose difference and 3mm distance to agreement. Results: More than 90% of PTV is covered by 100% of prescribed dose. Compared to TBI, average dose reduction on critical organs are: lung(10%), kidney(53%), liver(48%), Eyes(69%), and heart(51%). Junction areas show average 98% gamma passing rate and 3% absolute dose difference; volumetric portal dosimetry show average 91% gamma passing rate and 2% absolute dose difference, compared to plan dose. Conclusions: Adequate target dose coverage and reduced normal organ d

关键词： Dosimetry Medical treatment planning Medical imaging Anatomy Computed tomography Ionization chambers computer science and technology Intensity modulated radiation therapy Therapeutics Ionic conduction

来源：评论

学校读者我要写书评

暂无评论

MO-D-BRB-02: Maximum Kinetic Energy Considerations in Coplanar Arc-Based Proton Stereotactic Radiosurgery

引用

Medical Physics 2011年第6PART25期38卷 3709-3709页

作者： E Sengbusch T Mackie University of Wisconsin Madison WI

Purpose: To determine the maximum proton kinetic energy required to treat a given percentage of patients eligible for stereotactic radiosurgery (SRS) with coplanar arc-based proton therapy, contingent upon the number and location of gantry angles used. Methods: Treatment plans from 100 consecutive patients treated with SRS at the University of Wisconsin Carbone Cancer Center between June of 2007 and March of 2010 were analyzed. For each target volume within each patient, in-house software was used to place proton pencil beam spots over the distal surface of the target volume from 51 equally spaced gantry angles over 360 degrees. For each beam spot, the radiological pathlength from the surface of the patient to the distal boundary of the target was then calculated along a ray from the gantry location to the location of the beam spot. This data was used to generate a maximum proton energy requirement for each patient as a function of the arc length that would be spanned by the gantry angles used in a given treatment. Results: If only a single treatment angle is required, 100 percent of the patients included in the study could be treated by a proton beam with a maximum kinetic energy of 118 MeV. As the length of the treatment arc is increased to 90, 180, 270, and 360 degrees, the maximum energy requirement increased to 127, 145, 156, and 179 MeV, respectively. Conclusions: A large percentage of SRS patients could be treated at relatively low proton energies if the gantry angles used in the treatment plan do not span a large treatment arc. Maximum proton kinetic energy requirements increase linearly with size of the treatment arc. A dedicated proton SRS system could cost much less than existing proton systems due to decreased energy requirements. This work was supported by the Department of Defense (DoD) through the National Defense science & Engineering Graduate Fellowship (NDSEG) Program and by a National science Foundation Graduate Fellowship. This work utilized the

关键词： Protons Radiosurgery Graduates Therapeutics Fellowships Signal generators Proton therapy Cancer computer software computer science and technology

来源：评论

学校读者我要写书评

暂无评论

TH-B-110-01: Informatics in Radiation Oncology

引用

Medical Physics 2011年第6PART34期38卷 3850-3850页

作者： R Siochi University Of Iowa Iowa City IA

Informatics covers not only the information technology (IT) and infrastructure required to support data collection and management but also the computer science concepts that turn data into knowledge. In radiation oncology, medical physicists need to be familiar with the basic IT infrastructure that makes it possible to transfer and transform data through clinical processes that ultimately control radiation treatment delivery. The application of informatics continues with patient outcomes. Typically, this happens through participation in national protocols (e.g. RTOG). While they provide a framework for evidence-based medicine, the data are often limited to parameters that were designed to test a pre-defined hypothesis. As the ability to acquire and distribute data increases, we may be able to adopt data mining approaches to discover knowledge, even without asking specific questions. While simple database queries can efficiently provide statistical information (e.g. the NCI Surveillance, Epidemiology and End Results, SEER), data mining seeks hidden patterns through clustering, classification, regression and association. These principles can be applied to large volumes of concisely described data sets, similar to what can be found in clinical trials. Researchers in radiation oncology informatics are developing the infrastructure to acquire large data sets. The Radiation Oncology Data Alliance (RODA) initiative aims to provide online aggregate de-identified data from participating users of the MOSAIQ EMR. Borrowing from the field of astronomy, researchers from Johns Hopkins used the SkyServer framework to build the OncoSpace project. The NCI caBIG (Cancer Bioinformatics Grid) also provides infrastructure support. Data analytics have also been developing in parallel, with researchers structuring the data collection phases to answer questions in Comparative Effectiveness Research (CER). While a majority of researchers look for links between treatment and outcome, others

关键词： Informatics Cancer Researchers Data mining Radiation treatment computer science and technology Radiation therapy Data sets Medical physicists computer aided diagnosis

来源：评论

学校读者我要写书评

暂无评论

TU-A-301-03: A Multi-Dimensional Description of Breast Anatomy Using Breast CT

引用

Medical Physics 2011年第6PART28期38卷 3745-3745页

作者： S Huang J Boone K Yang N Packard S McKenney N Prionas M Yaffe K Lindfors University of California Davis Davis CA Carestream Health Inc. Rochester NY University Toronto Toronto ON CA

Purpose: Accurate anatomical characterization of the breast is useful in breast phantom development, computer modeling of breast imaging technologies, and computer-aided diagnosis of various imaging tasks. Using the breast CT (bCT) data sets of women from a clinical trial, a number of two-dimensional (2D) and three-dimensional (3D) parameters which describe breast shape and composition are presented. Methods: The diameter, length, and volume of the pendant breast were measured for 219 bCT data sets, grouped by bra cup size. Segmented bCT data sets were used to determine the volume glandular fraction (VGF). VGF was found as a function of patient age, BIRADS density, and bra cup size. The glandular fraction was examined in coronal (GFcoronal and sagittal (GFsagittal) planes of the breast, and the radial distribution of breast glandular fraction (RGFn) within a coronal bCT image was examined for three breast regions. The areal glandular fraction (AGF) was estimated from 2D projections of the breast (simulated by linear integration of bCT data sets) and was compared to the corresponding VGF. A 3D probability map of fibroglandular distribution was simulated using the breast metrics found in this study. Results: Breast diameter, length, and volume increase with increasing bra cup size. VGF was lower among older women and those with larger bra cup size. For each increasing BIRADS category, VGF increased by 5.62% (p < 0.001). VGF was also found to increase with AGF following a power function. Most fibroglandular tissue was distributed mainly in the central portion of the breast. Conclusions: Breast anatomy was examined and a number of parameters were described. The reported data may provide useful information for breast modeling in various imaging or dosimetry tasks.

关键词： Medical imaging Data sets Computed tomography Anatomy computer science and technology computer modeling Tissues Dosimetry

来源：评论

学校读者我要写书评

暂无评论

SU-E-J-157: Investigation of Gated Cone-Beam CT to Reduce Respiratory Motion Blurring

引用

Medical Physics 2011年第6PART9期38卷 3479-3479页

作者： R Kincaid E Yorke A Rimner G Mageras Memorial Sloan-Kettering Cancer Center New York NY

Purpose: Respiration-correlated cone-beam CT (RC-CBCT) using slow continuous gantry rotation is commonly used to reduce respiratory motion blurring but image quality is limited by uneven projection spacing. This study investigates the efficacy of a novel gated CBCT technique (gantry motion and imaging only within gate) in reducing motion blur with improved image quality using a new type of computer-controlled linac (Varian TrueBeam).Methods: For gated CBCT, the linac is programmed to gate gantry rotation and kV image acquisition with approximately 25% duty cycle around end expiration. The two-part study examines images in phantom and prospectively in patients with thoracic and abdominal tumors. A motion phantom is programmed to follow a patient respiratory trace (1.4cm mean excursion) and CBCT scans are performed in standard “free-breathing”, RC-CBCT, and gated CBCT modes. A standard CBCT of the stationary phantom serves as ground truth. Evaluation of phantom image quality compares contrast-to-noise ratios (CNR) of spheres embedded in acrylic, delineated on the static image and aligned to the other images. In patient studies, image fidelity in standard free-breathing and gated CBCT is compared relative to a respiration-correlated CT (RCCT) on the same day, by computing a cross-correlation metric (CCM) in an ROI around the internal target volume following rigid ***: CNR in motion phantom for gated CBCT is nearly that for static phantom (ratio gated/static 0.95) and larger than for RC-CBCT (ratio 1.64) and standard CBCT (1.22). CCM of the tumor ROI in gated CBCT is larger than standard CBCT in all three thoracic cases thus far (ratio gated/standard mean 1.04 range 1.03–1.06), indicating higher congruence with the ground-truth RCCT Conclusions: Gated CBCT visibly reduces image blurring caused by respiratory motion. By exploiting recent computer-controlled linac technology, complete projection sets can be acquired within a gate, yielding improved recons

关键词： Cone beam computed tomography Medical imaging Medical image quality Linear accelerators Computed tomography Cancer Medical image noise Medical image reconstruction computer science and technology Digital image processing

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：