Cost-effective Algorithm Research Articles

A Systematic Approach for Dynamic Security Assessment and the Corresponding Preventive Control Scheme Based on Decision Trees

This paper proposes a decision tree (DT)-based systematic approach for cooperative online power system dynamic security assessment (DSA) and preventive control. This approach adopts a new methodology that trains two contingency-oriented DTs on a daily basis by the databases generated from power system simulations. Fed with real-time wide-area measurements, one DT of measurable variables is employed for online DSA to identify potential security issues, and the other DT of controllable variables provides online decision support on preventive control strategies against those issues. A cost-effective algorithm is adopted in this proposed approach to optimize the trajectory of preventive control. The paper also proposes an importance sampling algorithm on database preparation for efficient DT training for power systems with high penetration of wind power and distributed generation. The performance of the approach is demonstrated on a 400-bus, 200-line operational model of western Danish power system.

Screening for celiac disease in 1st degree relatives: a 10-year follow-up study

BackgroundAlthough it is known that first degree relatives of celiac patients have an increased risk for celiac disease few studies are available on its incidence. We investigated the incidence of serologic conversion and of new cases of celiac disease among first degree relatives with negative results at a first screening.MethodsFrom a total of 634 first degree relatives of 186 biopsy-proven celiac disease patients diagnosed between October 2000 and October 2010, 450 subjects agreed to participate in the study (Group I), and underwent serologic screening. Between January 2010 and October 2012, out of the initial group of 450, 205 previously sero-negative subjects consented to participate in a second stage of the study and undergo new serologic testing (Group II). All serologically positive individuals of both groups (I and II) were genotyped for celiac disease-predisposing alleles (HLA-DQ2/DQ8).Results19 subjects (4.2%) out of the 450 subjects of Group I disclosed positive serologic results, presence of DQ2 and/or DQ8 alleles and celiac disease-compatible mucosal abnormalities. The 205 previously negative first degree relatives from Group II that underwent new serologic testing disclosed eight sero-converted subjects. Mucosal abnormalities in five of these patients confirmed the diagnosis of celiac disease. During the 10-year period of the study the incidence of sero-conversion was 8/205 and the incidence of biopsy-proven celiac disease cases was 5/205.ConclusionsOur data are coincident with other works on this subject and confirm once again that relatives of celiac patients, especially first degree relatives are at high risk of developing celiac disease. In view of the relatively low incidence further studies are needed to try to establish a useful and cost-effective algorithm for follow-up of relatives of celiac patients.

Estimation Of Global Positioning System Measurement Errors For GAGAN Applications

The Global Positioning System (GPS) has been in use for providing positioning, navigation and timing (PNT) services in many parts of the world. There are several errors that affect the positional accuracy of GPS. Prominent among them are ephemeris errors, satellite and receiver clock errors, multipath errors, signal propagation errors such as ionospheric delay, tropospheric delay, and instrumental biases of the satellite and receiver. In this paper, prominent estimation techniques to characterize various GPS measurement errors are reviewed. The GPS data in the Receiver INdependent EXchange (RINEX) format obtained from a Dual frequency GPS receiver is used in this analysis. Among all the errors, ionospheric delay is found to be the most dominant. However, these delay measurements are affected by the satellite and receiver instrumental biases. The instrumental biases exist as the signals at the two GPS frequencies experience different delays inside the satellite and receiver hardware. For estimation of the instrumental biases Extended Kalman filter(EKF) technique is adopted. The user equivalent range error (UERE) obtained due to all the error sources is of the order of few metres. After accounting for various errors, the estimation accuracy is significantly improved.The positional accuracy of the GPS Aided GEO Augmented Navigation (GAGAN) system is basically dependent on ranging errors and the satellite constellation geometry(1). The lineof-sight ionospheric measurements derived from the Global Positioning System (GPS) observables are corrupted by the instrumental biases present in both the GPS satellites and the receivers. The instrumental bias and Total Electron Content (TEC) results (Hyderabad GAGAN station (78.47°E, 17.45°N)) obtained using theExtended Kalman filter technique are presented in this paper. In this work the main focus is towards development of an improved error free approach for aircraft navigation. The existing navigation solutions are based on iterative algorithms and require an initial estimate of the receiver position for computing the navigation solution which is not possible in all conditions. Accurate, reliable and cost effective navigation solution algorithms that suit the Indian geographic area and area of application are proposed in this work. A non-iterative point solution approach algorithm computes the navigation solution based on the available satellite positions and pseudorange measurements(3). The improvement in GPS system has given a feasibility of automated operation of satellite based augmenting system in aircraft navigation can augment GAGAN and improves the positional accuracy of the user. In this paper a communication approach , high, accurate processing using EKF scheme is proposed for GPS aided geo augmented navigation (GAGAN) application. The effectiveness of the proposed approach for higher performance is evaluated under variable conditions.

Improved Reverse Screening Algorithm for Treponema pallidum Antibody Using Signal-to-Cutoff Ratios from Chemiluminescence Microparticle Immunoassay

The widespread reverse syphilis screening algorithm involves 1 more treponemal test than the traditional screening algorithm, resulting in increased medical costs. In the first screening step of the algorithm, a chemiluminescence microparticle immunoassay is used to detect Treponema pallidum (TP) antibody on the basis of signal-to-cutoff (S/CO) ratios. We hypothesized that by analyzing S/CO ratios, we could determine a strategy to reduce unnecessary confirmatory testing. The ARCHITECT Syphilis TP assay using the chemiluminescence microparticle immunoassay was used as a syphilis screening test, and all reactive results were followed up with a toluidine red unheated serum test (TRUST) and a TP particle agglutination (TPPA) assay. We evaluated the S/CO ratios of 319 reactive samples of a total of 8980 that were included in the screening tests. A receiver operating characteristic curve was used to determine the optimal S/CO ratio to predict confirmatory TPPA results. When the S/CO ratio was 9.9 or greater, the specificity and positive predictive value were both determined to be 100.0%. All samples (194/194) with S/CO ratios of 9.9 or greater, even with negative results for TRUST, were confirmed to be positive for treponemal antibody. A sample with an S/CO ratio of 9.9 or greater in initial screening does not need an extra confirmatory TPPA test, although the sample has a negative result for TRUST. We propose a potentially cost-effective reverse screening algorithm, obviating the need for the secondary treponemal testing in 65.2% of the screening-reactive samples.

Predictors of Well Developed Coronary Collateral Circulation in Patients with Stable Angina Pectoris

Objective: We aimed to demonstrate the predictors of Coronary Collateral Development (CCD) in patients with Stable Angina Pectoris (SAP). Methods: We prospectively enrolled 52 patients with at least 90% coronary stenosis. Their demographic, anthropometric and clinical data as well as hematological and biochemical parameters, medications, Ejection Fraction (EF) and perfusion index values and angiographic findings were used for determining the predictors for CCD. The Rentrop score (between 0 and 3) was used for the angiographic categorization and patients in Rentrop grades 0 and 1 were classified as poor CCD, and patients in Rentrop grades 2 and 3 were classified as well CCD. Results: We found moderate negative correlation between the Rentrop score and ejection fraction (r=-0,469, p<0.001). There was also positive correlation between the Gensini score (GS) and the Rentrop score (r=0.627, p<0.001). We made Classification and Regression Tree Model (C&RT) to define best predictors of CCD and found that EF (cut off 55%) and GS (cut off 41%) together constitute a useful prediction algorithm. Furthermore an advanced research was conducted to develop another algorithm to forecast coronary collateral development prior to angiography. The analysis was repeated after the extraction of angiographic data from the first C&RT model. It was concluded that EF (cut off 55%) and mean platelet volume (MPV) (cut off 9 fl) can be used in the second algorithm. Conclusions: CCD is negatively related to EF and positively related to GS. EF and MPV together constitute a simple and cost effective algorithm to predict the CCD before the angiography. However, GS and EF seem to be the best predictors of CCD among the whole variables.

Mild Cognitive Impairment: A Brief Review and Suggested Clinical Algorithm.

Mild cognitive impairment (MCI) is a dynamic state between normal cognition and dementia, where interventions can be taken to stop or delay the progression to dementia. It is broadly of 2 types-amnestic, where memory loss is the chief concern and nonamnestic, where it is not. One variant of nonamnestic, dysexecutive, being more prevalent is sometimes known as a separate subtype by itself. Diagnosis of MCI is mostly clinical and is aided by various scales and neuropsychological testing. Functional imaging studies help in early detection and is superior to biomarkers or structural magnetic resonance imaging. Although there is no evidence supporting any pharmacological intervention, cognitive rehabilitation, memory training, and caregiver support play a strong role in limiting and sometimes reversing the ongoing cognitive decline. As the spectrum of MCI is heterogeneous, making the right diagnosis can be a challenging; hence, we need a systematic yet cost-effective algorithm for the timely management of MCI.

Early Referral for Esophageal pH Monitoring Is More Cost-Effective Than Prolonged Empiric Trials of Proton-Pump Inhibitors for Suspected Gastroesophageal Reflux Disease

IntroductionThe most cost-effective diagnostic algorithm for gastroesophageal reflux disease (GERD) remains controversial. We hypothesized that prompt referral for esophageal pH monitoring is more cost-effective than prolonged empiric courses of proton-pump inhibitors (PPIs). DiscussionA cost model was created based on a cohort of 100 patients with possible GERD who underwent pH monitoring. The additional costs incurred from pH monitoring were compared to the potential savings from avoiding unnecessary PPI usage in patients with a negative pH study. The costs of PPI therapy reach equivalence with pH monitoring after 6.4 to 23.7 weeks, depending on the PPI regimen. A total of 21,411 weeks of PPIs were prescribed beyond the recommended 8-week trial, of which 32 % were for patients who had a negative 24-h pH monitoring study. If the sensitivity of pH monitoring was 96 %, early referral for pH monitoring would have saved between $1,197 and $6,303 per patient over 10 years. This strategy remains cost-effective as long as the sensitivity of pH monitoring is above 35 %. Prompt referral for pH monitoring after a brief empiric PPI trial is a more cost-effective strategy than prolonged empiric PPI trials for patients with both esophageal and extraesophageal GERD symptoms.

Clinical Impact of Early CT Scans after Lateral Skull‐Base Surgery

To determine the frequency and clinical significance of abnormalities on postoperative computerized tomography (CT) scans performed within 24 hours after lateral skull base surgery. Case series with chart review. Setting Inpatient tertiary care hospital. Adult patients undergoing lateral skull base surgery were identified using CPT code search from January 2010 to January 2013. Patient demographics, type of skull base lesion, surgical approach, length of operation, time between end of the surgery and CT scan, CT scan findings, and patients' postsurgical neurologic status were collected. One hundred and seventy-two patients were identified who had a postoperative CT scan after lateral skull base surgery. Diagnoses included schwannoma (95), cerebrospinal fluid fistula (29), middle fossa encephaloceles (9), meningioma (13), superior semicircular canal dehiscence (12), and other disease processes (14). The approaches were middle fossa (64), translabyrinthine (70), suboccipital (17), infratemporal (8), and combined/other (13). Mild pneumocephalus was almost always found, along with mild extra-axial blood. Twenty-four patients had significant mass effect found on CT scan, but this was present preoperatively. Three patients had a mild subdural without neurological decline. No patient suffered any clinically significant neurological decline, although 5 patients reported finger numbness that resolved spontaneously and 2 patients had confusion in the immediate postoperative period. Clinically significant abnormalities on immediate postoperative CT scans were rare, as were cases of neurological decline. Further prospective studies could determine a more cost-effective algorithm for routine use of postoperative imaging.

EGFR,KRAS,BRAFandALKgene alterations in lung adenocarcinomas: patient outcome, interplay with morphology and immunophenotype

Numerous studies have been published on single aspects of pulmonary adenocarcinoma (ADC). To comprehensively link clinically relevant ADC characteristics, we evaluated established morphological, diagnostic and predictive biomarkers in 425 resected ADCs. Morphology was reclassified. Cytokeratin-7, thyroid transcription factor (TTF)1, napsin A, thymidylate synthase and excision repair cross-complementing rodent repair deficiency complementation group-1 expression, anaplastic lymphoma kinase rearrangements as well as epidermal growth factor receptor (EGFR), V-Ki-ras2 Kirsten rat sarcoma viral oncogene homologue (KRAS) and v-Raf murine sarcoma viral oncogene homologue B1 (BRAF) mutations were analysed. All characteristics were correlated with clinical and survival parameters. Morphological ADC subtypes were significantly associated with smoking history and distinct patterns of diagnostic biomarkers. KRAS mutations were prevalent in male smokers, while EGFR mutations were associated with female sex, nonsmoking and lepidic as well as micropapillary growth patterns. TTF1 expression (hazard ratio (HR) for overall survival 0.61, p=0.021) and BRAF mutations (HR for disease-free survival 2.0, p=0.046) were found to be morphology- and stage-independent predictors of survival in multivariate analysis. Adjuvant radio-/chemotherapy, in some instances, strongly impacted on the prognostic effect of both diagnostic and predictive biomarkers. Our data draw a comprehensive picture of the prevalence and interplay of established histological and molecular ADC characteristics. These data will help to develop time- and cost-effective diagnostic and treatment algorithms for ADC.

Federated IMM-UKF Algorithm for Multi-Sensor Data Fusion

The accuracy of multi-sensor navigational data fusion by federated Kalman filter will be reduced in condition that the systems dynamics model is nonlinear and the noise statistical properties are unknown. To address this problem, a federated Interacting Multiple Model-Unscented Kalman Filteing (IMM-UKF) algorithm is presented. The UKF is a nonlinear estimation method which can achieve the accuracy at least to the second-order. The IMM estimation algorithm is one of the cost-effective adaptive estimation algorithm for systems involving parametric changes. The combination of IMM with UKF could deal with the problem of nonlinear filtering with uncertain noise. Simulation results show that the method can improve the accuracy of INS/GPS/odometer integrated navigation.

New Strategies for Carcinoma of Unknown Primary: The Role of Tissue-of-Origin Molecular Profiling

The taxonomy and management of carcinoma of unknown primary (CUP) has matured over the past decade with the use of sophisticated imaging and pathologic tools. In the era of tailored therapeutics, this presents both an opportunity and a challenge. Tissue-of-origin (ToO) molecular profiling has an important role in the diagnostic armamentarium of CUP cancers, and its niche continues to evolve with ongoing prospective studies. Despite the inability to conduct direct validation (i.e., primary tumor), the use of the indirect validation methods with immunohistochemistry (IHC), imaging, and treatment response has allowed us to evaluate the performance accuracy of ToO profiling assays in CUP cancers. Despite advances, we struggle with the undifferentiated neoplasms, which often remain unclassifiable after an exhaustive use of IHC and ToO profiling assays. Genomic characterization of these and other select CUP cancers using next-generation sequencing techniques may reveal actionable biomarkers outside the (tissue specific) cellular framework. Also, going forward, using data from comparative effectiveness research, one could envision using a streamlined, cost-effective algorithm that integrates IHC and ToO molecular profiling in patients with limited (or difficult-to-access) biopsies and difficult-to-diagnose cancers.

On Modifications to the Spectral Dichotomy Algorithm

We introduce modifications of an existing spectral dichotomy algorithm [6] with respect to a circle for general regular matrix pencils. The modifications result in a cost-effective algorithm, mathematically equivalent to the original one, but six times less expensive. The algorithm approximates iteratively the spectral projector onto the right deflating subspace associated with the eigenvalues inside/outside the circle as well as a criterion to ascertain its numerical quality. We also show how to approximate the left projector from the algorithm without any extra work. Effective stopping criteria for the algorithm are discussed. Numerical examples which illustrate the theory are presented.

Evaluation of the thyroid nodule

Thyroid nodules are the most common endocrine tumor, affecting over 50% of women over age 50. While the incidence of thyroid cancer is increasing, most thyroid nodules ultimately prove benign. An accurate, cost-effective algorithm for the evaluation of thyroid nodules includes clinical, biochemical, ultrasonographic and cytopathologic evaluation. The development of molecular diagnostics promises to transform the interpretation of previously indeterminate cytology results, but application of these techniques requires a thorough understanding of the impact of pre-test probability of malignancy on the performance of the molecular assays. Efforts to avoid diagnostic surgery in nodules that are cytologically indeterminate are admirable, but may be premature, pending additional confirmatory studies that prove this approach is safe. Meanwhile, the finding of oncogene mutations has sufficient specificity for cancer that this approach might be useful to tailor surgery. However, the cost effectiveness of this approach requires further evaluation.

Cost-effectiveness and optimal diagnostic sequence of CT, MRI, and PET-CT in the management of colorectal liver metastases.

4132 Background: CT, PET-CT and MRI play a role in the decision making process in managing colorectal liver metastases (CRLM). This study aimed to determine the optimal sequence of these investigations in order to reduce the rate of futile laparotomy and improve cost effectiveness of treatment. Methods: All patients referred to our specialist multidisciplinary team (sMDT) with CRLM were reviewed to investigate specific reason(s) for not offering potentially curative surgery. Clinical parameters were recorded for analysis. Three hypothetical scenarios were derived for cost-effectiveness analyses: 1) “up-front” with all imaging prior to sMDT, 2) “sequential”, with individual imaging following each sMDT, and 3) “hybrid” with PET-CT and MRI after review of the initial CT scan. Results: 644 consecutive patients were reviewed. Following assessment of initial CT, 165 patients (26%) were referred for palliative chemotherapy. After further evaluation by PET +/- MRI, 307 patients proceeded for potentially curative resection. Of those excluded from surgery, 48% were following PET-CT. Median overall survival (OS) for the resection and palliative groups were 46 and 14 months respectively (p&lt;0.001). Futile laparotomy rate was 5.5%.The optimum strategy of lowest average time to decision, and lowest average cost is the hybrid model. Cost-utility analyses demonstrated a saving of approx. £319 (USD$ 515) per patient compared to the other 2 models. Conclusions: Decision making regarding further imaging after initial CT scan for CRLM should be performed at the sMDT to minimise delays and maximise efficiency of resources allocation. Triple assessment with CT, PET and MRI and sMDT decision process may reduce risk of futile laparotomy. A hybrid model using PET and MRI following a sMDT discussion of the initial CT provides the most cost effective algorithm for the management of CRLM.

Contact angle estimation and composite locomotive strategy of a stair-climbing mobile platform

This paper presents a stair-climbing mobile platform built on the Rocker–Bogie mechanism which enables to effectively climb up/down various sizes of stairs in indoor environments without violating its mobile stability. First, the link parameters of Rocker–Bogie mechanism are optimally chosen via the Taguchi method in order to make the trajectory of its center of mass (CM) as smooth as possible, which implies high mobile stability as well as excellent adaptability during climbing up/down stairs. Based on this optimization result, the proposed mobile platform is compactly and lightly constructed suitable for indoor applications by placing all motors and sensors inside the hollow links in order to prevent undesired interferences with stairs as well as to protect themselves from external impact. A simple, robust and cost-effective estimation algorithm is proposed to detect the contact angles between wheels and a stair with high fidelity. Through the kinematic and kinetic analysis combined with the wheel-stair contact angle information, a composite locomotive strategy is established not only to minimize the slip during climbing up a stair but also to prevent falling down during climbing down a stair. The extensive experiments against various types of stairs successfully demonstrate the capability of the proposed mobile platform to effectively and safely climb up/down stairs.

Risk stratification of patients with normal myocardial perfusion imaging: help comes from the periphery

This editorial refers to ‘Value of reserve pulse pressure in improving the risk stratification of patients with normal myocardial perfusion imaging’, by D. Thomas et al. , doi:10.1093/eurheartj/eht102 Nuclear imaging has an established clinical role in the non-invasive diagnosis of coronary artery disease (CAD), allowing accurate patient stratification and allocation to the best form of treatment. Semi-quantitative assessment of regional myocardial perfusion with single-photon emission computed tomography (SPECT) is a non-invasive, robust, and widely available method of assessing myocardial ischaemia and has a well established role in the clinical setting. One of the recognized strengths of SPECT perfusion imaging is its very high negative prognostic value. The annual rate of death and non-fatal myocardial infarction in patients with normal stress SPECT perfusion imaging is <1% per annum, i.e. similar to that in the general population.1 A recent retrospective study by Rozanski et al .2 reports a decline in the frequency of abnormal perfusion detected by stress myocardial perfusion imaging (MPI) with SPECT in North America over the last two decades. The frequency of an abnormal myocardial perfusion image is now very low in patients able to exercise without typical angina. These findings highlight the need for developing cost-effective diagnostic algorithms for symptomatic patients who are at low risk and do not show inducible myocardial ischaemia during MPI. On the other hand, a normal myocardial perfusion image is not the equivalent of a normal coronary circulation: diffuse atherosclerosis, balanced ischaemia, and microvascular dysfunction hamper the increase of myocardial blood flow during exercise without showing localized perfusion defects. Histopathology studies have shown that atherosclerosis is diffuse in nature, and in symptomatic patients chest pain is often considered non-coronary because no single focal stenosis is found …

Potent and Stealthy Control Flow Obfuscation by Stack Based Self-Modifying Code

Software code released to the user has the risk of reverse engineering attacks. Software obfuscation techniques can be employed to make the reverse engineering of software programs harder. In this paper, we propose a potent, stealthy, and cost-effective algorithm to obfuscate software programs. The main idea of the algorithm is to remove control flow information from the code area and hide them in the data area. During execution time, these instructions are reconstructed, thereby preserving the semantics of the program. Experimental results indicate that the algorithm performs well against static and dynamic attacks. Also the obfuscated program is hard to be differentiated from normal binary programs demonstrating the obfuscations good stealth measure.

Referrer Graph: A cost-effective algorithm and pruning method for predicting web accesses

This paper presents the Referrer Graph (RG) web prediction algorithm and a pruning method for the associated graph as a low-cost solution to predict next web users accesses. RG is aimed at being used in a real web system with prefetching capabilities without degrading its performance. The algorithm learns from users accesses and builds a Markov model. These kinds of algorithms use the sequence of the user accesses to make predictions. Unlike previous Markov model based proposals, the RG algorithm differentiates dependencies in objects of the same page from objects of different pages by using the object URI and the referrer in each request. Although its design permits us to build a simple data structure that is easier to handle and, consequently, needs lower computational cost in comparison with other algorithms, a pruning mechanism has been devised to avoid the continuous growing of this data structure. Results show that, compared with the best prediction algorithms proposed in the open literature, the RG algorithm achieves similar precision values and page latency savings but requiring much less computational and memory resources. Furthermore, when pruning is applied, additional and notable resource consumption savings can be achieved without degrading original performance. In order to reduce further the resource consumption, a mechanism to prune de graph has been devised, which reduces resource consumption of the baseline system without degrading the latency savings.

A novel cost effective algorithm for antinuclear antibody (ANA) testing in an outpatient setting

A novel cost effective algorithm for antinuclear antibody (ANA) testing in an outpatient setting

Estimation of Spectral Bounds in Gradient Algorithms

We consider the solution of linear systems of equations Ax=b, with A a symmetric positive-definite matrix in ? n×n , through Richardson-type iterations or, equivalently, the minimization of convex quadratic functions (1/2)(Ax,x)?(b,x) with a gradient algorithm. The use of step-sizes asymptotically distributed with the arcsine distribution on the spectrum of A then yields an asymptotic rate of convergence after k<n iterations, k??, that coincides with that of the conjugate-gradient algorithm in the worst case. However, the spectral bounds m and M are generally unknown and thus need to be estimated to allow the construction of simple and cost-effective gradient algorithms with fast convergence. It is the purpose of this paper to analyse the properties of estimators of m and M based on moments of probability measures ? k defined on the spectrum of A and generated by the algorithm on its way towards the optimal solution. A precise analysis of the behavior of the rate of convergence of the algorithm is also given. Two situations are considered: (i) the sequence of step-sizes corresponds to i.i.d. random variables, (ii) they are generated through a dynamical system (fractional parts of the golden ratio) producing a low-discrepancy sequence. In the first case, properties of random walk can be used to prove the convergence of simple spectral bound estimators based on the first moment of ? k . The second option requires a more careful choice of spectral bounds estimators but is shown to produce much less fluctuations for the rate of convergence of the algorithm.