Search results for "Cutoff"
showing 10 items of 84 documents
Broadband X-ray spectral variability of the pulsing ULX NGC 1313 X-2
2021
[Context] It is thought that ultraluminous X-ray sources (ULXs) are mainly powered by super-Eddington accreting neutron stars or black holes as shown by the recent discovery of X-ray pulsations and relativistic winds. [Aims] This work presents a follow-up study of the spectral evolution over two decades of the pulsing ULX NGC 1313 X-2 in order to understand the structure of the accretion disc. The primary objective is to determine the shape and nature of the dominant spectral components by investigating their variability with the changes in the source luminosity. [Methods[ We performed a spectral analysis over the canonical 0.3-10.0 keV energy band of all the high signal-to-noise XMM-Newton…
Comparison of the yield from two faecal immunochemical tests at identical cutoff concentrations – a randomized trial in Latvia
2016
OBJECTIVE We have compared the performance of two faecal immunochemical tests (FIT) in an average-risk population. MATERIALS AND METHODS Altogether, 10 000 individuals aged 50-74 were selected randomly from the population of Latvia in 2011 and assigned randomly either to OC-Sensor or to FOB Gold single-time testing. Positivity of the test, frequency of colonic lesions, number needed to screen (NNscreen) and scope for the detection of an advanced neoplasm (cancer and advanced adenoma) were compared between the tests using the same cutoff concentrations in µg/g faeces. Confidence intervals (CIs) at 95% were calculated. RESULTS Positivity with the cutoff set at 10 µg/g faeces was 12.8% (95% CI…
Single region of interest versus multislice T2* MRI approach for the quantification of hepatic iron overload.
2011
Purpose To evaluate the effectiveness of the single ROI approach for the detection of hepatic iron burden in thalassemia major (TM) patients in respect to a whole liver measurement. Materials and Methods Five transverse hepatic slices were acquired by a T2* gradient-echo sequence in 101 TM patients and 20 healthy subjects. The T2* value was calculated in a single region of interest (ROI) defined in the medium-hepatic slice. Moreover, the T2* value was extracted on each of the eight ROIs defined in the functionally independent segments. The mean hepatic T2* value was calculated. Results For patients, the mean T2* values over segments VII and VIII were significantly lower. This pattern was su…
Accommodative stimulus-response curves to low-pass filtered natural images
2018
To assess how the monocular steady-state accommodative stimulus-response curve is modified when viewing low-pass filtered natural images. Eighteen adult subjects participated in the study. The accommodative stimulus-response curve was objectively assessed by means of a Hartmann-Shack wavefront sensor. Measurements were taken at different accommodative demands. Target images were low-pass filtered versions of a natural image that were obtained applying different digital spatial filters that limited the spatial frequency content of the natural image. Cutoff spatial frequencies were set at 30, 21, and 15 cycles per degree (cy/deg). Mean data obtained for each target were fitted to linear model…
Resovist enhanced MR imaging of the liver: Does quantitative assessment help in focal lesion classification and characterization?
2009
Purpose: To improve characterization of focal liver lesions by a prospective quantitative analysis of percentage signal intensity change, in dynamic and late phases after slow (0.5 mL/s) Resovist administration. Materials and Methods: Seventy-three patients were submitted on clinical indication to MR examination with Resovist. Signal intensity of 92 detected focal lesions (5–80 mm) were measured with regions of interest and normalized to paravertebral muscle in arterial, portal, equilibrium and T1/T2 late phases, by two observers in conference. Five values of percentage variations per patient were obtained and statistically evaluated. Results: The enhancement obtained on dynamic study is mo…
Predictive biomarkers for complicated acute appendicitis: A prospective Ecuadorian study.
2020
The aim of the study was to determine the usefulness of known biomarkers as pre-operative predictors of complicated acute appendicitis (CAA) and perforated appendicitis (PA).This was an observational, analytic, cross-sectional, and prospective study at Hospital Teodoro Maldonado Carbo (August 2016-December 2017). Evaluated biomarkers: white blood cells count, neutrophil percentage (N%), neutrophil-to-lymphocyte ratio, glucose, total bilirubin, C-reactive protein, and procalcitonin (PCT). The statistical analysis was performed by means of the area under the receiver operating characteristics (AUROC) curve estimation. Biomarkers' cutoff point was identified using Youden's index. Sensitivity, …
Pretherapeutic MRI for decision-making regarding selective neoadjuvant radiochemotherapy for rectal carcinoma: interim analysis of a multicentric pro…
2012
Purpose: To study the accuracy of different cutoffs for an involved circumferential resection margin (CRM) compared with T and N categories measured by MRI as basis for selective application of neoadjuvant radiochemotherapy (nRCT) in rectal carcinoma. Materials and Methods: In a prospective multicenter observational study involving 153 primarily operated patients, the preoperative results of MRI with pathohistological findings of resected specimens were compared. Results: For a cutoff of ≤1 mm for involvement of the CRM, the accuracy of preoperative MRI was 90.9% (139/153). The negative predictive value was 98.5% (134/136). The four participating departments did not differ significantly. Fo…
Simplified criteria for the diagnosis of autoimmune hepatitis
2008
Diagnosis of autoimmune hepatitis (AIH) may be challenging. However, early diagnosis is important because immunosuppression is life-saving. Diagnostic criteria of the International Autoimmune Hepatitis Group (IAIHG) were complex and purely meant for scientific purposes. This study of the IAIHG aims to define simplified diagnostic criteria for routine clinical practice. Candidate criteria included sex, age, autoantibodies, immunoglobulins, absence of viral hepatitis, and histology. The training set included 250 AIH patients and 193 controls from 11 centers worldwide. Scores were built from variables showing predictive ability in univariate analysis. Diagnostic value of each score was assesse…
Difference in Mortality Risk in Elderly People with Bronchial Obstruction Diagnosed Using a Fixed Cutoff or the Lower Limit of Normal of the FEV1/FVC…
2017
Background: Whether a fixed cutoff or the lower limit of normal of the FEV1/FVC ratio should be used to diagnose bronchial obstruction is still a matter of debate. This issue is particularly important for elderly people. Objectives: We used equations applicable up to 90 years of age to evaluate the mortality of elderly people diagnosed with bronchial obstruction using either a fixed cutoff of 0.7 or the lower limit of normal (LLN). Methods: Participants in the SaRA (Salute Respiratoria nell'Anziano, Italian for "Respiratory Health in the Elderly") study were grouped as follows: FEV1/FVC ≥0.7 and ≥ LLN (n = 535: F-/L-), FEV1/FVC <0.7 but ≥ LLN (n = 118: F+/L-), and FEV1/FVC <0.7 and < LLN (n…
Fundamental-mode cutoff in liquid-filled Y-shaped microstructured fibers with Ge-doped core
2008
We report on the cutoff characteristics of a Ge-doped Y-shaped microstructured fiber in which the holes are filled with a liquid of refractive index higher than silica but lower than the Ge-doped core. It is found that the cutoff wavelength was very sensitive to temperature variations as a result of the refractive index changes of the liquid. The basic properties of such a fiber permit the fabrication of wideband tunable short-pass filters, as well as temperature sensors with high sensitivity. A temperature sensitivity of 25 nm/degrees C is reported.