Ovarian-adnexal reporting and data system ultrasound evaluation and pathological characteristics of ovarian collision tumor

BACKGROUND Collision tumor are neoplasms,including two histologically distinct tumors that coexist in the same mass without histological admixture.The incidence of collision tumor is low and is rare clinically.AIM To investigate ultrasound images and application of ovarian-adnexal reporting and data system(O-RADS)to evaluate the risk and pathological characteristics of ovarian collision tumor.METHODS This study retrospectively analyzed 17 cases of ovarian collision tumor diagnosed pathologically from January 2020 to December 2023.All clinical features,ultrasound images and histopathological features were collected and analyzed.The O-RADS score was used for classification.The O-RADS score was determined by two senior doctors in the gynecological ultrasound group.Lesions with O-RADS score of 1-3 were classified as benign tumors,and lesions with O-RADS score of 4 or 5 were classified as malignant tumors.RESULTS There were 17 collision tumors detected in 16 of 6274 patients who underwent gynecological surgery.The average age of 17 women with ovarian collision tumor was 36.7 years(range 20-68 years),in whom,one occurred bilaterally and the rest occurred unilaterally.The average tumor diameter was 10 cm,of which three were 2-5 cm,11 were 5-10 cm,and three were>10 cm.Five(29.4%)tumors with O-RADS score 3 were endometriotic cysts with fibroma/serous cystadenoma,and unilocular or multilocular cysts contained a small number of parenchymal components.Eleven(64.7%)tumors had an O-RADS score of 4,including two in category 4A,six in category 4B,and three in category 4C;all of which were multilocular cystic tumors with solid components or multiple papillary components.One(5.9%)tumor had an O-RADS score of 5.This case was a solid mass,and a small amount of pelvic effusion was detected under ultrasound.The pathology was high-grade serous cystic cancer combined with cystic mature teratoma.There were nine(52.9%)tumors with elevated serum carbohydrate antigen(CA)125 and two(11.8%)with elevated serum CA19-9.Histological and pathological results showed that epithelial-cell-derived tumors combined with other tumors were the most common,which was different from previous results.CONCLUSION The ultrasound images of ovarian collision tumor have certain specificity,but diagnosis by preoperative ultrasound is difficult.The combination of epithelial and mesenchymal cell tumors is one of the most common types of ovarian collision tumor.The O-RADS score of ovarian collision tumor is mostly≥4,which can sensitively detect malignant tumors.

Hepatocellular carcinoma Liver Imaging Reporting and Data Systems treatment response assessment: Lessons learned and future directions

Hepatocellular carcinoma(HCC)is a leading cause of morbidity and mortality worldwide,with rising clinical and economic burden as incidence increases.There are a multitude of evolving treatment options,including locoregional therapies which can be used alone,in combination with each other,or in combination with systemic therapy.These treatment options have shown to be effective in achieving remission,controlling tumor progression,improving disease free and overall survival in patients who cannot undergo resection and providing a bridge to transplant by debulking tumor burden to downstage patients.Following locoregional therapy(LRT),it is crucial to provide treatment response assessment to guide management and liver transplant candidacy.Therefore,Liver Imaging Reporting and Data Systems(LI-RADS)Treatment Response Algorithm(TRA)was created to provide a standardized assessment of HCC following LRT.LIRADS TRA provides a step by step approach to evaluate each lesion independently for accurate tumor assessment.In this review,we provide an overview of different locoregional therapies for HCC,describe the expected post treatment imaging appearance following treatment,and review the LI-RADS TRA with guidance for its application in clinical practice.Unique to other publications,we will also review emerging literature supporting the use of LI-RADS for assessment of HCC treatment response after LRT.

Reliable transmission of consultative committee for space data systems file delivery protocol in deep space communication

In consultative committee for space data systems（CCSDS） file delivery protocol（CFDP） recommendation of reliable transmission,there are no detail transmission procedure and delay calculation of prompted negative acknowledge and asynchronous negative acknowledge models.CFDP is designed to provide data and storage management,story and forward,custody transfer and reliable end-to-end delivery over deep space characterized by huge latency,intermittent link,asymmetric bandwidth and big bit error rate（BER）.Four reliable transmission models are analyzed and an expected file-delivery time is calculated with different trans-mission rates,numbers and sizes of packet data units,BERs and frequencies of external events,etc.By comparison of four CFDP models,the requirement of BER for typical missions in deep space is obtained and rules of choosing CFDP models under different uplink state informations are given,which provides references for protocol models selection,utilization and modification.

Contrast-enhanced ultrasound Liver Imaging Reporting and Data System:Lights and shadows in hepatocellular carcinoma and cholangiocellular carcinoma diagnosis

BACKGROUND Contrast-enhanced ultrasound(CEUS)is considered a secondary examination compared to computed tomography(CT)and magnetic resonance imaging(MRI)in the diagnosis of hepatocellular carcinoma(HCC),due to the risk of misdiagnosing intrahepatic cholangiocarcinoma(ICC).The introduction of CEUS Liver Imaging Reporting and Data System(CEUS LI-RADS)might overcome this limitation.Even though data from the literature seems promising,its reliability in real-life context has not been well-established yet.AIM To test the accuracy of CEUS LI-RADS for correctly diagnosing HCC and ICC in cirrhosis.METHODS CEUS LI-RADS class was retrospectively assigned to 511 nodules identified in 269 patients suffering from liver cirrhosis.The diagnostic standard for all nodules was either biopsy(102 nodules)or CT/MRI(409 nodules).Common diagnostic accuracy indexes such as sensitivity,specificity,positive predictive value(PPV),and negative predictive value(NPV)were assessed for the following associations:CEUS LR-5 and HCC;CEUS LR-4 and 5 merged class and HCC;CEUS LR-M and ICC;and CEUS LR-3 and malignancy.The frequency of malignant lesions in CEUS LR-3 subgroups with different CEUS patterns was also determined.Inter-rater agreement for CEUS LI-RADS class assignment and for major CEUS pattern identification was evaluated.RESULTS CEUS LR-5 predicted HCC with a 67.6%sensitivity,97.7%specificity,and 99.3%PPV(P<0.001).The merging of LR-4 and 5 offered an improved 93.9%sensitivity in HCC diagnosis with a 94.3%specificity and 98.8%PPV(P<0.001).CEUS LR-M predicted ICC with a 91.3%sensitivity,96.7%specificity,and 99.6%NPV(P<0.001).CEUS LR-3 predominantly included benign lesions(only 28.8%of malignancies).In this class,the hypo-hypo pattern showed a much higher rate of malignant lesions(73.3%)than the iso-iso pattern(2.6%).Inter-rater agreement between internal raters for CEUS-LR class assignment was almost perfect(n=511,k=0.94,P<0.001),while the agreement among raters from separate centres was substantial(n=50,k=0.67,P<0.001).Agreement was stronger for arterial phase hyperenhancement(internal k=0.86,P<2.7×10-214;external k=0.8,P<0.001)than washout(internal k=0.79,P<1.6×10-202;external k=0.71,P<0.001).CONCLUSION CEUS LI-RADS is effective but can be improved by merging LR-4 and 5 to diagnose HCC and by splitting LR-3 into two subgroups to differentiate iso-iso nodules from other patterns.

Reliability of ultrasound ovarian-adnexal reporting and data system amongst less experienced readers before and after training

BACKGROUND The 2018 ovarian-adnexal reporting and data system(O-RADS)guidelines are aimed at providing a system for consistent reports and risk stratification for ovarian lesions found on ultrasound.It provides key characteristics and findings for lesions,a lexicon of descriptors to communicate findings,and risk characterization and associated follow-up recommendation guidelines.However,the ORADS guidelines have not been validated in North American institutions or amongst less experienced readers.AIM To evaluate the diagnostic accuracy and inter-reader reliability of ultrasound ORADS risk stratification amongst less experienced readers in a North American institution with and without pre-test training.METHODS A single-center retrospective study was performed using 100 ovarian/adnexal lesions of varying O-RADS scores.Of these cases,50 were allotted to a training cohort and 50 to a testing cohort via a non-randomized group selection process in order to approximately equal distribution of O-RADS categories both within and between groups.Reference standard O-RADS scores were established through consensus of three fellowship-trained body imaging radiologists.Three PGY-4 residents were independently evaluated for diagnostic accuracy and inter-reader reliability with and without pre-test O-RADS training.Sensitivity,specificity,positive predictive value,negative predictive value(NPV),and area under the curve(AUC)were used to measure accuracy.Fleiss kappa and weighted quadratic(pairwise)kappa values were used to measure inter-reader reliability.Statistical significance was P<0.05.RESULTS Mean patient age was 40±16 years with lesions ranging from 1.2 to 22.5 cm.Readers demonstrated excellent specificities(85%-100%pre-training and 91%-100%post-training)and NPVs(89%-100%pre-training and 91-100%post-training)across the O-RADS categories.Sensitivities were variable(55%-100%pre-training and 64%-100%post-training)with malignant ORADS 4 and 5 Lesions pre-training and post-training AUC values of 0.87-0.95 and 0.94-098,respectively(P<0.001).Nineteen of 22(86%)misclassified cases in pre-training were related to mischaracterization of dermoid features or wall/septation morphology.Fifteen of 17(88%)of posttraining misclassified cases were related to one of these two errors.Fleiss kappa inter-reader reliability was‘good’and pairwise inter-reader reliability was‘very good’with pre-training and post-training assessment(k=0.76 and 0.77;and k=0.77-0.87 and 0.85-0.89,respectively).CONCLUSION Less experienced readers in North America achieved excellent specificities and AUC values with very good pairwise inter-reader reliability.They may be subject to misclassification of potentially malignant lesions,and specific training around dermoid features and smooth vs irregular inner wall/septation morphology may improve sensitivity.

Interobserver agreement for contrast-enhanced ultrasound of liver imaging reporting and data system:A systematic review and metaanalysis

BACKGROUND Hepatocellular carcinoma is the most common primary liver malignancy.From the results of previous studies,Liver Imaging Reporting and Data System(LIRADS)on contrast-enhanced ultrasound(CEUS)has shown satisfactory diagnostic value.However,a unified conclusion on the interobserver stability of this innovative ultrasound imaging has not been determined.The present metaanalysis examined the interobserver agreement of CEUS LI-RADS to provide some reference for subsequent related research.AIM To evaluate the interobserver agreement of LI-RADS on CEUS and analyze the sources of heterogeneity between studies.METHODS Relevant papers on the subject of interobserver agreement on CEUS LI-RADS published before March 1,2020 in China and other countries were analyzed.The studies were filtered,and the diagnostic criteria were evaluated.The selected references were analyzed using the“meta”and“metafor”packages of R software version 3.6.2.RESULTS Eight studies were ultimately included in the present analysis.Meta-analysis results revealed that the summary Kappa value of included studies was 0.76[95%confidence interval,0.67-0.83],which shows substantial agreement.Higgins I2 statistics also confirmed the substantial heterogeneity(I2=91.30%,95%confidence interval,85.3%-94.9%,P<0.01).Meta-regression identified the variables,including the method of patient enrollment,method of consistency testing,and patient race,which explained the substantial study heterogeneity.CONCLUSION CEUS LI-RADS demonstrated overall substantial interobserver agreement,but heterogeneous results between studies were also obvious.Further clinical investigations should consider a modified recommendation about the experimental design.

Validation of Vesical Imaging Reporting and Data System score for the diagnosis of muscle-invasive bladder cancer: A prospective cross-sectional study

Objective:Vesical Imaging Reporting and Data System(VIRADS)score was developed to standardize the reporting and staging of bladder tumors on pre-operative multiparametric magnetic resonance imaging.It helps in avoiding unnecessary repeat transurethral resection of bladder tumor in high-risk non-muscle-invasive bladder cancer patients.This study was done to determine the validity of VIRADS score prospectively for the diagnosis of muscleinvasive bladder cancer.Methods:This study was conducted from March 2019 to March 2020 at Sawai Man Singh Medical College and Hospital,Jaipur,Rajasthan,India.Patients admitted with the provisional diagnosis of bladder tumor were included as participants.All these patients underwent a 3 Tesla mpMRI to obtain a VIRADS score before they underwent transurethral resection of bladder tumor and these data were analyzed to evaluate the correlation of pre-operative VIRADS score with mus-cle invasiveness of the tumor in final biopsy report.Results:A cut-off of VIRADS≥4 for prediction of detrusor muscle invasion yielded a sensitivity of 79.4%,specificity of 94.2%,positive predictive value of 90.0%,negative predictive value of 87.5%,and diagnostic accuracy of 86.4%.A cut off of VIRADS≥3 for prediction of detrusor muscle invasion yielded a sensitivity of 91.2%,specificity of 78.8%,positive predictive value of 73.8%,negative predictive value of 93.2%,and accuracy of 83.7%.The receiver operating curve showed the area under the curve to be 0.922(95%confidence interval:0.862e0.983).Conclusion:VIRADS score appears to be an excellent and effective pre-operative radiological tool for the prediction of detrusor muscle invasion in bladder cancer.

Liver Imaging Reporting and Data System criteria for the diagnosis of hepatocellular carcinoma in clinical practice: A pictorial minireview

Hepatocellular carcinoma(HCC)is the sixth most common cancer.The main risk factors associated with HCC development include hepatitis B virus,hepatitis C virus,alcohol consumption,aflatoxin B1,and nonalcoholic fatty liver disease.However,hepatocarcinogenesis is a complex multistep process.Various factors lead to hepatocyte malignant transformation and HCC development.Diagnosis and surveillance of HCC can be made with the use of liver ultrasound(US)every 6 mo.However,the sensitivity of this imaging method to detect HCC in a cirrhotic liver is limited,due to the abnormal liver parenchyma.Computed tomography(CT)and magnetic resonance imaging(MRI)are considered to be most useful tools for at-risk patients or patients with inadequate US.Liver biopsy is still used for diagnosis and prognosis of HCC in specific nodules that cannot be definitely characterized as HCC by imaging.Recently the American College of Radiology designed the Liver Imaging Reporting and Data System(LI-RADS),which is a comprehensive system for standardized interpretation of CT and MRI liver examinations that was first proposed in 2011.In 2018,it was integrated into the American Association for the Study of Liver Diseases guidance statement for HCC.LI-RADS is designed to ensure high sensitivity,precise categorization,and high positive predictive value for the diagnosis of HCC and is applied to“highrisk populations”according to specific criteria.Most importantly LI-RADS criteria achieved international collaboration and consensus among liver experts around the world on the best practices for caring for patients with or at risk for HCC.

Novel Stability Criteria for Sampled-Data Systems With Variable Sampling Periods

This paper is concerned with a novel Lyapunovlike functional approach to the stability of sampled-data systems with variable sampling periods. The Lyapunov-like functional has four striking characters compared to usual ones. First, it is time-dependent. Second, it may be discontinuous. Third, not every term of it is required to be positive definite. Fourth, the Lyapunov functional includes not only the state and the sampled state but also the integral of the state. By using a recently reported inequality to estimate the derivative of this Lyapunov functional, a sampled-interval-dependent stability criterion with reduced conservatism is obtained. The stability criterion is further extended to sampled-data systems with polytopic uncertainties. Finally, three examples are given to illustrate the reduced conservatism of the stability criteria.

Carrier Frequency Offset Estimation for FM and Symbiotic FM Radio Data System Hybrid Signal

The symbiotic FM radio data system(SRDS)is a radio data system that a specially designed OFDM signal co-lives with FM signal,which enables a significantly higher data rate than existing radio data systems.The cyclic prefix of the OFDM symbol has the same length as the OFDM body,which enables the analytic separation of the co-channel OFDM and FM signal at receiver side,utilizing the fact that the OFDM body and prefix is equal.In this work,we show that the OFDM body and prefix cannot be viewed as equal when there is sufficient carrier frequency offset(CFO).Thus,we propose a two-step CFO estimation algorithm for FM and SRDS hybrid signal.The first step estimates the coarse CFO by exploring the characteristics of the FM signal.Once the coarse CFO is removed,the residual CFO is small enough for FM and OFDM separation.The second step fine estimates CFO from the OFDM-only signal using its repeated PN structure after the separation.Detailed mathematical equations are formulated and simulation results are given.The results show that the proposed algorithm works fine with the simulation setup and has a final residual CFO less than 3.9Hz.

Effect of training on resident inter-reader agreement with American College of Radiology Thyroid Imaging Reporting and Data System

BACKGROUND The American College of Radiology Thyroid Imaging Reporting and Data System(ACR TI-RADS)was introduced to standardize the ultrasound characterization of thyroid nodules.Studies have shown that ACR-TIRADS reduces unnecessary biopsies and improves consistency of imaging recommendations.Despite its widespread adoption,there are few studies to date assessing the inter-reader agreement amongst radiology trainees with limited ultrasound experience.We hypothesize that in PGY-4 radiology residents with no prior exposure to ACR TIRADS,a statistically significant improvement in inter-reader reliability can be achieved with a one hour training session.AIM To evaluate the inter-reader agreement of radiology residents in using ACR TIRADS before and after training.METHODS A single center retrospective cohort study evaluating 50 thyroid nodules in 40 patients of varying TI-RADS levels was performed.Reference standard TI-RADS scores were established through a consensus panel of three fellowship-trained staff radiologists with between 1 and 14 years of clinical experience each.Three PGY-4 radiology residents(trainees)were selected as blinded readers for this study.Each trainee had between 4 to 5 mo of designated ultrasound training.No trainee had received specialized TI-RADS training prior to this study.Each of the readers independently reviewed the 50 testing cases and assigned a TI-RADS score to each case before and after TI-RADS training performed 6 wk apart.Fleiss kappa was used to measure the pooled inter-reader agreement.The relative diagnostic performance of readers,pre-and post-training,when compared against the reference standard.RESULTS There were 33 females and 7 males with a mean age of 56.6±13.6 years.The mean nodule size was 19±14 mm(range from 5 to 63 mm).A statistically significant superior inter-reader agreement was found on the post-training assessment compared to the pre-training assessment for the following variables:1.“Shape”(k of 0.09[slight]pre-training vs 0.67[substantial]post-training,P<0.001),2.“Echogenic foci”(k of 0.28[fair]pre-training vs 0.45[moderate]post-training,P=0.004),3.‘TI-RADS level’(k of 0.14[slight]pre-training vs 0.36[fair]post-training,P<0.001)and 4.‘Recommendations’(k of 0.36[fair]pre-training vs 0.50[moderate]post-training,P=0.02).No significant differences between the preand post-training assessments were found for the variables'composition','echogenicity'and'margins'.There was a general trend towards improved pooled sensitivity with TI-RADS levels 1 to 4 for the post-training assessment while the pooled specificity was relatively high(76.6%-96.8%)for all TI-RADS level.CONCLUSION Statistically significant improvement in inter-reader agreement in the assigning TI-RADS level and recommendations after training is observed.Our study supports the use of dedicated ACR TI-RADS training in radiology residents.

Robust H_2 control for uncertain sampled-data systems

A new approach is proposed for robust H2 problem of uncertain sampled-data systems. Through introducing a free variable, a new Lyapunov asymptotical stability criterion with less conservativeness is established. Based on this criterion, some sufficient conditions on two classes of robust H2 problems for uncertain sampled-data control systems axe presented through a set of coupled linear matrix inequalities. Finally, the less conservatism and potential of the developed results are illustrated via a numerical example.

Robust H_∞ controller design for sampled-data systems with parametric uncertainties

This article investigates the problem of robust H∞ controller design for sampled-data systems with time-varying norm-bounded parameter uncertainties in the state matrices. Attention is focused on the design of a causal sampled-data controller, which guarantees the asymptotical stability of the closed-loop system and reduces the effect of the disturbance input on the controlled output to a prescribed H∞ performance bound for all admissible uncertainties. Sufficient condition for the solvability of the problem is established in terms of linear matrix inequalities （LMIs）. It is shown that the desired H∞ controller can be constructed by solving certain LMIs. An illustrative example is given to demonstrate the effectiveness of the proposed method.

HL-2A Tokamak Experiment Data System

HL-2A tokamak experiment data system （ HL-2A EDS ） consists of an experiment network, various of dada acquiring sub-systems, a great deal of realtime data processing applications, a display system, a lot of interacting data analyzing workstations, a data storage system, a management platform, and a high performance computer. The system was built start in 2002, and has been modified greatly since then.

Contrast-enhanced ultrasound improved performance of breast imaging reporting and data system evaluation of critical breast lesions

AIM: To determine whether contrast-enhanced ultrasound(CEUS) can improve the precision of breast imaging reporting and data system(BI-RADS) categorization. METHODS: A total of 230 patients with 235 solid breast lesions classified as BI-RADS 4 on conventional ultrasound were evaluated. CEUS was performed within one week before core needle biopsy or surgical resection and a revised BI-RADS classification was assigned based on 10 CEUS imaging characteristics. Receiver operating characteristic curve analysis was then conducted to evaluate the diagnostic performance of CEUS-based BI-RADS assignment with pathological examination as reference criteria. RESULTS: The CEUS-based BI-RADS evaluation classified 116/235(49.36%) lesions into category 3, 20(8.51%), 13(5.53%) and 12(5.11%) lesions into categories 4A, 4B and 4C, respectively, and 74(31.49%) into category 5. Selecting CEUS-based BI-RADS category 4A as an appropriate cut-off gave sensitivity and specificity values of 85.4% and 87.8%, respectively, for the diagnosisof malignant disease. The cancer-to-biopsy yield was 73.11% with CEUS-based BI-RADS 4A selected as the biopsy threshold compared with 40.85% otherwise, while the biopsy rate was only 42.13% compared with 100% otherwise. Overall, only 4.68% of invasive cancers were misdiagnosed.CONCLUSION: This pilot study suggests that evaluation of BI-RADS 4 breast lesions with CEUS results in reduced biopsy rates and increased cancer-to-biopsy yields.

Predictive model for contrast-enhanced ultrasound of the breast: Is it feasible in malignant risk assessment of breast imaging reporting and data system 4 lesions?

AIM: To build and evaluate predictive models for contrast-enhanced ultrasound(CEUS) of the breast to distinguish between benign and malignant lesions. METHODS: A total of 235 breast imaging reporting and data system(BI-RADS) 4 solid breast lesions were imaged via CEUS before core needle biopsy or surgical resection. CEUS results were analyzed on 10 enhancing patterns to evaluate diagnostic performance of three benign and three malignant CEUS models, with pathological results used as the gold standard. A logistic regression model was developed basing on the CEUS results, and then evaluated with receiver operating curve(ROC). RESULTS: Except in cases of enhanced homogeneity, the rest of the 9 enhancement appearances were statistically significant(P < 0.05). These 9 enhancement patterns were selected in the final step of the logistic regression analysis, with diagnostic sensitivity and specificity of 84.4% and 82.7%, respectively, and the area under the ROC curve of 0.911. Diagnostic sensitivity, specificity, and accuracy of the malignant vs benign CEUS models were 84.38%, 87.77%, 86.38% and 86.46%, 81.29% and 83.40%, respectively. CONCLUSION: The breast CEUS models can predict risk of malignant breast lesions more accurately, decrease false-positive biopsy, and provide accurate BIRADS classification.

Components and Development in Big Data System: A Survey

With the growth of distributed computing systems, the modern Big Data analysis platform products often have diversified characteristics. It is hard for users to make decisions when they are in early contact with Big Data platforms. In this paper, we discussed the design principles and research directions of modern Big Data platforms by presenting research in modern Big Data products. We provided a detailed review and comparison of several state-ofthe-art frameworks and concluded into a typical structure with five horizontal and one vertical. According to this structure, this paper presents the components and modern optimization technologies developed for Big Data, which helps to choose the most suitable components and architecture from various Big Data technologies based on requirements.

Magnetic resonance imaging ancillary features used in Liver Imaging Reporting and Data System:An illustrative review

Hepatocellular carcinoma (HCC) usually develops in the setting of chronic liver disease. In the adequate clinical context, both multiphasic contrast-enhanced CT and magnetic resonance imaging are non-invasive modalities that allow accurate diagnosis and staging of HCC, although the latter demonstrates greater sensitivity and specificity. Imaging criteria for HCC diagnosis rely on hemodynamic features such as hyperenhancement in the arterial phase and washout in the portal or equilibrium phase. However, imaging performance drops considerably for small (< 20 mm) nodules because their tendency to exhibit atypical enhancement patterns. In order to improve accuracy in the diagnosis and staging of HCC, particularly in cases of atypical nodules, ancillary features, i.e., imaging characteristics that modify the likelihood of HCC, have been described and incorporated into clinical reports, especially in Liver Imaging Reporting and Data System. In this paper, ancillary imaging features will be reviewed and illustrated.

TPTVer： A Trusted Third Party Based Trusted Verifier for Multi-Layered Outsourced Big Data System in Cloud Environment

Cloud computing is very useful for big data owner who doesn't want to manage IT infrastructure and big data technique details. However, it is hard for big data owner to trust multi-layer outsourced big data system in cloud environment and to verify which outsourced service leads to the problem. Similarly, the cloud service provider cannot simply trust the data computation applications. At last,the verification data itself may also leak the sensitive information from the cloud service provider and data owner. We propose a new three-level definition of the verification, threat model, corresponding trusted policies based on different roles for outsourced big data system in cloud. We also provide two policy enforcement methods for building trusted data computation environment by measuring both the Map Reduce application and its behaviors based on trusted computing and aspect-oriented programming. To prevent sensitive information leakage from verification process,we provide a privacy-preserved verification method. Finally, we implement the TPTVer, a Trusted third Party based Trusted Verifier as a proof of concept system. Our evaluation and analysis show that TPTVer can provide trusted verification for multi-layered outsourced big data system in the cloud with low overhead.

Security and Privacy Frameworks for Access Control Big Data Systems

In the security and privacy fields,Access Control(AC)systems are viewed as the fundamental aspects of networking security mechanisms.Enforcing AC becomes even more challenging when researchers and data analysts have to analyze complex and distributed Big Data(BD)processing cluster frameworks,which are adopted to manage yottabyte of unstructured sensitive data.For instance,Big Data systems’privacy and security restrictions are most likely to failure due to the malformed AC policy configurations.Furthermore,BD systems were initially developed toped to take care of some of the DB issues to address BD challenges and many of these dealt with the“three Vs”(Velocity,Volume,and Variety)attributes,without planning security consideration,which are considered to be patch work.Some of the BD“three Vs”characteristics,such as distributed computing,fragment,redundant data and node-to node communication,each with its own security challenges,complicate even more the applicability of AC in BD.This paper gives an overview of the latest security and privacy challenges in BD AC systems.Furthermore,it analyzes and compares some of the latest AC research frameworks to reduce privacy and security issues in distributed BD systems,which very few enforce AC in a cost-effective and in a timely manner.Moreover,this work discusses some of the future research methodologies and improvements for BD AC systems.This study is valuable asset for Artificial Intelligence(AI)researchers,DB developers and DB analysts who need the latest AC security and privacy research perspective before using and/or improving a current BD AC framework.