Search results for "Regression"
showing 10 items of 2619 documents
Survival analysis of proposed BCLC-B subgroups in hepatocellular carcinoma patients
2013
Background & Aims The BCLC-staging system is used to facilitate treatment decisions in patients with hepatocellular carcinoma (HCC). Owing to the observed clinical heterogeneity of the intermediate stage BCLC-B, a subclassification was proposed taking Child–Pugh score and extended criteria for transplantation into account. Analysis of the prognostic significance of a proposed subclassification of the BCLC-B score in a European cohort of HCC patients. Methods Eight hundred and eighty four consecutive HCC patients were retrospectively analysed. Patients with stage BCLC-B were grouped according to the proposed subclassification. Baseline patient and tumour characteristics, therapy and overall …
Ramucirumab in elderly patients with hepatocellular carcinoma and elevated alpha-fetoprotein after sorafenib in REACH and REACH-2.
2020
Background & Aims: Limited data on treatment of elderly patients with hepatocellular carcinoma (HCC) increase the unmet need. REACH and REACH-2 were global phase III studies of ramucirumab in patients with HCC after prior sorafenib, where patients with alpha-fetoprotein (AFP) ≥400 ng/mL showed an overall ssurvival (OS) benefit for ramucirumab. These post-hoc analyses examined efficacy and safety of ramucirumab in patients with HCC and baseline AFP ≥ 400 ng/mL by three prespecified age subgroups (<65, ≥65 to <75 and ≥75 years). Methods: Individual patient data were pooled from REACH (baseline AFP ≥400 ng/mL) and REACH-2. Kaplan-Meier and Cox proportional hazards regression methods …
Probabilité d'apparition d'un phénomène parasitaire et choix de modèles de régression logistique
2007
Epidemiological processes are now using spatial statistics and modelling tools. The main objective of most health risks studies consists in identifying potential contamination sources and factors capable of explaining their localization. Health data often prove binary (typically presence/absence) and specific methods such as binary logistic regression have to be used. This method's output consists in a probability for the pathogen of interest. A posterior classification of each sample is then conducted using a probability threshold. The method used to maximize this threshold is called the ROC curve which consists in giving a representation of the behaviour of the model and then to choose th…
Taking care of everyone’s business: interpreting Sicilian Mafia embedment through spatial network analysis
2022
Mafia-type organisations often have a strong geographical and cultural entrenchment in the territory they belong. However, their analysis as a spatially networked social structure is still missing. A combined socio-spatial network analysis is presented here, through the demise of a large police operation called Operazione Perseo in 2008. This approach is developed in two ways. At first, a visual representation of the social network of this large group of mafiosi embedded in a geographical space is presented. Three main salient territorial features of the network are thus highlighted. A high density of links in some neighbourhoods, as well as connections across different Mandamenti, the terr…
Rapid and Nondestructive Determination of Egg Freshness Category and Marked Date of Lay using Spectral Fingerprint
2020
The potential of nondestructive prediction of egg freshness based on near-infrared (NIR) spectra fingerprints would be beneficial to quality control officers and consumers alike. In this study, handheld NIR spectrometer in the range of 740 nm to 1070 nm and chemometrics were used to simultaneously determine egg freshness based on marked date of lay for eggs stored under cold and ambient conditions. The spectra acquired from the eggs were preprocessed using multiplicative scatter correction and principal component analysis (MSC-PCA). Linear discriminant analysis (LDA) was used to build identification model to predict the category of freshness, while partial least square regression (PLS-R) wa…
Non-destructive and clean prediction of aviation fuel characteristics through Fourier transform-Raman spectroscopy and multivariate calibration
2003
Abstract The combination of Fourier transform (FT)-Raman spectroscopy and partial least squares (PLS) regression is proposed to be used in off-line kerosene quality control. Here, six important physico-chemical properties have been studied: Abel flash point, initial boiling point (IBP), 10% of distilled sample, final boiling point (FBP), total percentage of aromatic compounds (% aromatics) and viscosity. The Raman spectra were obtained directly from standard 2 ml glass vials ( 12 mm ×32 mm), using a Bruker RFS 100 FT-Raman spectrometer, equipped with a 1064 nm Nd:YAG laser and a Ge detector, in back-scattering mode and accumulating 25 scans (150 s acquisition time) with a laser power of 30…
Green direct determination of mineral elements in artichokes by infrared spectroscopy and X-ray fluorescence.
2015
Near infrared (NIR) and X-ray fluorescence (XRF) spectroscopy were investigated to predict the concentration of calcium, potassium, iron, magnesium, manganese and zinc in artichoke samples. Sixty artichokes were purchased from different Spanish areas (Benicarlo, Valencia and Murcia). NIR and XRF spectra, combined with partial least squares (PLS) data treatment, were used to develop chemometric models for the prediction of mineral concentration. To obtain reference data, samples were mineralised and analysed by inductively coupled plasma optical emission spectrometry (ICP-OES). Coefficients of determination obtained for the regression between predicted values and reference ones for calcium, …
Determination of total phenolic compounds in compost by infrared spectroscopy
2016
Abstract Middle and near infrared (MIR and NIR) were applied to determine the total phenolic compounds (TPC) content in compost samples based on models built by using partial least squares (PLS) regression. The multiplicative scatter correction, standard normal variate and first derivative were employed as spectra pretreatment, and the number of latent variable were optimized by leave-one-out cross-validation. The performance of PLS-ATR-MIR and PLS-DR-NIR models was evaluated according to root mean square error of cross validation and prediction (RMSECV and RMSEP), the coefficient of determination for prediction ( R pred 2 ) and residual predictive deviation (RPD) being obtained for this la…
Chemometric determination of arsenic and lead in untreated powdered red paprika by diffuse reflectance near-infrared spectroscopy.
2008
It has been evaluated the potential of near-infrared (NIR) diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) as a way for non-destructive measurement of trace elements at microg kg(-1) level in foods, with neither physical nor chemical pre-treatment. Predictive models were developed using partial least-square (PLS) multivariate approaches based on first-order derivative spectra. A critical comparison of two spectral pre-treatments, multiplicative signal correction (MSC) and standard normal variate (SNV) was also made. The PLS models built after using SNV provided the best prediction results for the determination of arsenic and lead in powdered red paprika samples. Relativ…
Near Infrared Spectroscopy Detection and Quantification of Herbal Medicines Adulterated with Sibutramine.
2015
There is an increasing demand for herbal medicines in weight loss treatment. Some synthetic chemicals, such as sibutramine (SB), have been detected as adulterants in herbal formulations. In this study, two strategies using near infrared (NIR) spectroscopy have been developed to evaluate potential adulteration of herbal medicines with SB: a qualitative screening approach and a quantitative methodology based on multivariate calibration. Samples were composed by products commercialized as herbal medicines, as well as by laboratory adulterated samples. Spectra were obtained in the range of 14,000-4000 per cm. Using PLS-DA, a correct classification of 100% was achieved for the external validatio…