Semiparametric Inferential Procedures for Comparing Multivariate ROC Curves with Interaction Terms

Multivariate ROC curve models that include an interaction term be- tween biomarker type and false positive rate is important in comparative biomarker studies, because such interaction allows ROC curves of different biomarkers to cross each other. However, there has been limited work in drawing inference for comparing multivariate ROC curves, especially when the interaction terms are present. In this article we derive the asymptotic covariance of three estimators for multivariate ROC models. These covariance estimates have not been readily available in the literature, and bootstrap methods have to be used to obtain co- variance estimates. With the readily available variance estimates, we can easily perform hypothesis testing among ROC curves while bootstrap tests are not so easily performed. The asymptotic results are applied to compare ROC curves and their areas under ROC curves. Moreover, we derive simultaneous confidence bands for multivariate ROC curves. We evaluate and compare the finite sample performance of our asymptotic covariance estimators. We also discuss the ad- vantage of using our asymptotic results over bootstrap procedures. Finally, we illustrate our approach through a well-known pancreatic cancer study

Nonparametric and Semiparametric Group Sequential Methods for Comparing Accuracy of Diagnostic Tests

Comparison of the accuracy of two diagnostic tests using the receiver operating characteristic (ROC) curves from two diagnostic tests has been typically conducted using fixed sample designs. On the other hand, the human experimentation inherent in a comparison of diagnostic modalities argues for periodic monitoring of the accruing data to address many issues related to the ethics and efficiency of the medical study. To date, very little research has been done in the use of sequential sampling plans for comparative ROC studies, even when these studies may use expensive and unsafe diagnostic procedures. In this paper, we propose a nonparametric group sequential design plan. The nonparametric sequential method adapts a nonparametric family of weighted area under the ROC curve statistics (Wieand et al., Biometrika, 76: 585-592, 1989) and a group sequential sampling plan. We illustrate the implementation of this nonparametric approach for sequentially comparing ROC curves in the context of diagnostic screening for non-small cell lung cancer. We also describe a semiparametric sequential method based on proportional hazard models. We compare the statistical properties of the nonparametric approach to alternative semiparametric and parametric analyses in simulation studies. The results show the nonparametric approach is robust to model misspecification and has excellent finite sample performance

Anti-HER-2 engineering antibody ChA21 inhibits growth and induces apoptosis of SK-OV-3 cells

<p>Abstract</p> <p>Background and Aims</p> <p>Anti-HER-2 antibodies targeting distinct epitopes have different biological functions on cancer cells. In a previous study, we demonstrated that anti-HER-2 engineering antibody ChA21 was able to bind to subdomain I of HER-2 extracellular domain. In this study, The effects of ChA21 on growth and apoptosis against ovarian carcinoma cell SK-OV-3 over-expressing HER-2 <it>in vitro </it>and <it>in vivo </it>were investigated.</p> <p>Methods</p> <p>Cell growth inhibition was evaluated by MTT assay. Apoptosis was detected by TUNEL stain, transmission electron microscopy and flow cytometry on cultured cells and tissue sections from nude mice xenografts. The apoptosis-related proteins Bax and Bcl-2 were assessed by immunohistochemistry.</p> <p>Results</p> <p>We found that treatment of ChA21 caused a dose-dependent decrease of cell proliferation <it>in vitro </it>and a significant inhibition of tumor growth <it>in vivo</it>. ChA21 therapy led to a significant increase in the induction of apoptosis, and up-regulated the expression of Bax, while the expression of Bcl-2 was down-regulated.</p> <p>Conclusion</p> <p>These data suggest that ChA21 inhibits the growth and induces apoptosis of SK-OV-3 via regulating the balance between Bax and Bcl-2.</p

Ameliorative patterns of grey matter in patients with first-episode and treatment-naïve schizophrenia

Background Grey matter (GM) reduction is a consistent observation in established late stages of schizophrenia, but patients in the untreated early stages of illness display an increase as well as a decrease in GM distribution relative to healthy controls (HC). The relative excess of GM may indicate putative compensatory responses, though to date its relevance is unclear. Methods 343 first-episode treatment-naïve patients with schizophrenia (FES) and 342 HC were recruited. Multivariate source-based morphometry was performed to identify covarying \u27networks\u27 of grey matter concentration (GMC). Neurocognitive scores using the Cambridge Neuropsychological Test Automated Battery (CANTAB) and symptom burden using the Positive and Negative Symptoms Scale (PANSS) were obtained. Bivariate linear relationships between GMC and cognition/symptoms were studied. Results Compared to healthy subjects, FES had prominently lower GMC in two components; the first consists of the anterior insula, inferior frontal gyrus, anterior cingulate and the second component with the superior temporal gyrus, precuneus, inferior/superior parietal lobule, cuneus, and lingual gyrus. Higher GMC was seen in adjacent areas of the middle and superior temporal gyrus, middle frontal gyrus, inferior parietal cortex and putamen. Greater GMC of this component was associated with lower duration of untreated psychosis, less severe positive symptoms and better performance on cognitive tests. Conclusions In untreated stages of schizophrenia, both a distributed lower and higher GMC is observable. While the higher GMC is relatively modest, it occurs across frontoparietal, temporal and subcortical regions in association with reduced illness burden suggesting a compensatory role for higher GMC in the early stages of schizophrenia

Keyword Query Reformulation on Structured Data

Textual web pages dominate web search engines nowadays. However, there is also a striking increase of structured data on the web. Efficient keyword query processing on structured data has attracted enough attention, but effective query understanding has yet to be investigated. In this paper, we focus on the problem of keyword query reformulation in the structured data scenario. These reformulated queries provide alternative descriptions of original input. They could better capture users&apos; information need and guide users to explore related items in the target structured data. We propose an automatic keyword query reformulation approach by exploiting structural semantics in the underlying structured data sources. The reformulation solution is decomposed into two stages, i.e., offline term relation extraction and online query generation. We first utilize a heterogenous graph to model the words and items in structured data, and design an enhanced Random Walk approach to extract relevant terms from the graph context. In the online query reformulation stage, we introduce an efficient probabilistic generation module to suggest substitutable reformulated queries. Extensive experiments are conducted on a real-life data set, and our approach yields promising results.Computer Science, Theory &amp; MethodsEngineering, Electrical &amp; ElectronicCPCI-S(ISTP)

An approach for controller fault detection

Monitoring and maintaining of control software becomes more and more important and difficult with the increase of control software in size and complexity. In this paper, an approach for control software fault detection is proposed, which is based on the monitoring of the discrepancies between the control outputs of the actual controller and the benchmark controller, a Linear Quadratic Gaussian (LQG) controller. The discrepancies are assumed to be Gaussian distribution with a stable mean under the normal situation. Faults in the actual controller are characterized by sudden jumps in the mean of the discrepancies. The fault detection is transferred into a jump point identification problem. A detector based on Generalized Likelihood Ratio (GLR) test is employed for the jump point identification. The proposed approach is applicable to general control software even it is only illustrated through a water heater case study with a simple PID controller

Study of the effects on GPS coordinate time series caused by higher-order ionospheric corrections calculated using the DIPOLE model

As one of the main error sources in high-precision Global Positioning System (GPS) data processing, higher-order ionospheric (HOI) delays cause significant effects on coordinate time series that cannot be ignored in analyses of long time series. Typically two geomagnetic models, DIPOLE model and International Geomagnetic Reference Field (IGRF) model, are used for calculating HOI corrections. This paper investigates the effects of HOI correction caused by the DIPOLE model on coordinate time series. GPS data from 104 globally distributed International GNSS Service (IGS) stations spanning from January, 1999 to December, 2003 were reprocessed following up-to-date processing strategies utilizing GAMIT and GLOBK software. Two coordinate time series solutions before and after applying HOI corrections using the DIPOLE model were derived for studying the effects in terms of seasonal variations and noise amplitudes. The results show that after applying the HOI corrections calculated with DIPOLE, the noise amplitudes of the coordinate time series increased, especially in the north and east directions, and the increased amplitudes of the flicker noise were larger than those of the white noise. Furthermore, spurious periodic signals that were probably introduced by the HOI corrections from the DIPOLE model were also found. Moreover, an apparent increase was confirmed for the power spectra of most of the stations, especially in the north direction, and the amplitudes of both the annual and semi-annual signals also increased in the north and east directions. It can be inferred that the quality of the external data sources such as the geomagnetic model might be the key factors that lead to the above results. The results also suggest that we should be very careful when the DIPOLE model is used for HOI corrections

Experimental research on spray evaporative cooling system applied to air-cooled chiller condenser

This study investigates the performance of a refrigeration unit by applying a spray evaporative cooling system to an air-cooled chiller. Experiments are conducted in the temperate monsoon climate region by combining the spray evaporative cooling system with the air-cooled chiller. Moreover, this study adopts a new gas-liquid two-phase swirl nozzle, which is independently developed and characterized by high atomization quality and low energy consumption. The experimental results show that the power of the compressor is reduced, while the COP (Coefficient of Performance) of the air-cooled chiller increases by 4%-8% after the intervention of the spray evaporative cooling system. The spray cooling system contributes to an electricity savings of 2.37%-13.53% in air-cooled chiller systems. If a more reasonable spray evaporative cooling mode is used, such as controlling the water flows according to the cooling capacity and arranging the nozzle positions and angles reasonably, the COP of the air-cooled unit will be further improved

Effect of Non-Coal Heating and Traditional Heating on Indoor Environment of Rural Houses in Tianjin

In order to understand the effect of the non-coal heating and the traditional coal-fired heating on the indoor environment of the rural houses, the humidity environment and indoor air quality in several households were investigated during the heating period in Beichen District and Wuqing District of Tianjin, China. The results showed that the indoor average temperature for the heating by the electricity and the natural gas was higher than that by the traditional coal fire. The indoor relative humidity for the heating by the electricity and the natural gas was lower than that by the traditional coal fire. The indoor air quality (IAQ) for the heating by the electricity and the natural gas was better than that by the traditional coal fire. For traditional coal-fire heating households, the indoor pollutant emission (CO emission) by using the clean coal was lower than that by using the raw coal. The indoor ventilation rate which was an important parameter for the indoor air quality was generally poor in winter. The total volatile organic compounds (TVOC) emission in the indoors of the coal-fired heating households was generally higher than that of the non-coaled heating households

Mycotoxins in Maize Silage from China in 2019

Animal feed (including forage and silage) can be contaminated with mycotoxins. Here, 200 maize silage samples from around China were collected in 2019 and analyzed for regulated mycotoxins, masked mycotoxins (deoxynivalenol, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, and deoxynivalenol-3-glucoside), and emerging mycotoxins (beauvericin, enniatins, moniliformin, and alternariol). Deoxynivalenol and zearalenone were detected in 99.5% and 79.5% of the samples, respectively. Other regulated mycotoxins were detected in fewer samples. The highest deoxynivalenol and zearalenone concentrations were 3600 and 830 μg/kg, respectively. The most commonly detected masked mycotoxin was 15-acetyldeoxynivalenol, which was detected in 68.5% of the samples and had median and maximum concentrations of 61.3 and 410 μg/kg, respectively. The emerging mycotoxins beauvericin, alternariol, enniatin A, enniatin B1, and moniliformin were detected in 99.5%, 85%, 80.5%, 72.5%, and 44.5%, respectively, of the samples but at low concentrations (medians <25 μg/kg). The samples tended to contain multiple mycotoxins, e.g., the correlation coefficients for the relationships between the concentrations of beauvericin and deoxynivalenol, deoxynivalenol and zearalenone, and zearalenone and beauvericin were 1.0, 0.995, and 0.995, respectively. The results indicated that there needs to be more awareness of the presence of one or more masked and emerging mycotoxins in maize silage in China