Search results for "Algorithm"
showing 10 items of 4887 documents
Macrostructural EEG characterization based on nonparametric change point segmentation: application to sleep analysis
2001
In the present investigation a new methodology for macrostructural EEG characterization based on automatic segmentation has been applied to sleep analysis. A nonparametric statistical approach for EEG segmentation was chosen, because it minimizes the need for a priori information about a signal. The method provides the detection of change-points i.e. boundaries between quasi-stationary EEG segments based on the EEG characteristics within four fundamental frequency bands (delta, theta, alpha and beta). Polysomnographic data of 18 healthy subjects were analyzed. Our findings show that nonparametric change-point segmentation in combination with cluster analysis enables us to obtain a clear pic…
From algorithmic computing to direct retrieval: Evidence from number and alphabetic arithmetic in children and adults
1998
A number of theories of mental arithmetic suggest that the ability to solve simple addition and subtraction problems develops from an algorithmic strategy toward a strategy based on the direct retrieval of the result from memory. In the experiment presented here, 2nd and 12th graders were asked to solve two tasks of number and alphabet arithmetic. The subjects transformed series of 1 to 4 numbers or letters (item span) by adding or subtracting an operand varying from 1 to 4 (operation span). Although both the item and operation span were associated with major and identical effects in the case of both numbers and letters at 2nd grade, such effects were clearly observable only in the case of …
Computed tomography-based tracheobronchial image reconstruction allows selection of the individually appropriate double-lumen tube size
1999
Objectives: To determine whether individualized selection of double-lumen tubes or alternatives based on three-dimensional reconstruction of the tracheobronchial image from routine preoperative computed tomography (CT) scans leads to clinically appropriate choices. Design: Prospective observational study; comparison to historic controls. Setting: Anesthesia and radiology facilities of a university medical center. Participants: Forty-nine patients undergoing thoracic surgery requiring one-lung ventilation. Interventions: Three-dimensional image reconstruction of individual tracheobronchial anatomy was performed from routine preoperative spiral CT scans as well as from scans of five left-side…
Online detection of rem sleep based on the comprehensive evaluation of short adjacent eeg segments by artificial neural networks
1997
Abstract 1. 1. For scientific and clinical requirements the present objective is a robust automatic online algorithm to detect rapid eye movement (REM) steep from single channel sleep EEG data without using EMG or EOG information. 2. 2. For data preprocessing 20 seconds time periods of the continuous EEG activity are digitally filtered in 7 frequency bands. Then the RMS values of these filtered signals are calculated along segments of 2.5 seconds. The resulting matrix of RMS values is representing information on the power of the signal localized in time and frequency and serves as input to an artificial neural network. A pooled set of EEG data together with the corresponding manual evaluati…
A novel constitutional mutation affecting splicing of retinoblastoma tumor suppressor gene intron 23 causes partial loss of pRB activity.
2005
Hereditary predisposition to retinoblastoma is caused by germ line mutations in the RB1 gene. Genetic counseling of affected individuals and accurate risk prediction for their families requires identification of the disease causing mutation. Furthermore, the nature of a mutation can determine genetic penetrance, disease presentation and prognosis. We describe, and functionally characterize here, a novel mutant allele of RB1 present in the germ line of a patient with sporadic bilateral retinoblastoma. The mutation generates an operational splice acceptor site resulting in a predicted protein product with loss of 81 amino acids from its carboxy terminus. We demonstrate that the aberrantly spl…
Serial Measurement of Static and Dynamic Cerebrovascular Autoregulation After Brain Injury
2011
In patients with neuronal injury, the knowledge of the status of cerebrovascular autoregulation can help to optimize the management of the cerebral perfusion pressure. This study characterizes dynamic and static cerebrovascular autoregulation during the first 7 days after severe traumatic brain injury or intracranial hemorrhage.After approval from the IRB, 16 patients were studied. Cerebral blood flow velocity (CBFV) was measured daily for the assessment of dynamic (10 patients) and static (16 patients) cerebrovascular autoregulation in both the middle cerebral arteries using the transcranial Doppler sonography. Dynamic cerebrovascular autoregulation (dAR) was measured using the cuff-deflat…
Altered effective connectivity during working memory performance in schizophrenia: a study with fMRI and structural equation modeling
2003
The present study aimed to explore altered effective connectivity in schizophrenic patients while performing a 2-back working memory task. Twelve right-handed, schizophrenic patients treated with typical or atypical antipsychotics and 6 healthy control subjects were studied with fMRI while performing a "2-back" working memory task. Effective connectivity within a cortical-subcortical-cerebellar network for mnemonic information processing was assessed and compared between both groups. The path model included cortico-cortical connections comprising the parietal association cortex, ventrolateral prefrontal cortex (VLPFC), and the dorsolateral prefrontal cortex (DLPFC) as well as a cortico-cere…
Relationship between velocity and muscular endurance of the upper body
2018
Strength, power and muscular endurance tests have been developed as means of assessing people's physical abilities. However, testing may be expensive or time consuming. A method to reduce the time of physical assessment could be to use predictive algorithms for indirect assessment. The aim of this study will be to determine a relationship between strength, power and muscular endurance in order to identify predictors for an easier and faster assessment. 33 male strength-trained participants (22.8 ± 4.6 years, 172.5 ± 6.7 cm, 68.0 ± 10.6 kg) performed a single pull-up (SPU) and a single push-up (SPH) and a set of pull-ups (EPU) and push-ups (EPH) to exhaustion. The participants were divided i…
Reference interval by the indirect approach of serum thyrotropin (TSH) in a Mediterranean adult population and the association with age and gender.
2019
Abstract Background The serum concentration of thyrotropin (TSH) represents a first-line test in diagnostic algorithms. The estimation of TSH reference intervals (RIs) is still a matter of debate due to the high prevalence of subclinical disease making difficult the definition of truly healthy subjects. The aim of this study was to estimate TSH RIs in healthy subjects and to evaluate the effect of age and gender on TSH concentration. Methods Forty-four thousand one hundred and fifty-six TSH data were collected between July 2012 and April 2018 at the Department of Laboratory Medicine, University-Hospital, Palermo. Common and sex-specific RIs were estimated by Arzideh’s indirect method after …
Quantitative analysis of emphysema in 3D using MDCT: Influence of different reconstruction algorithms
2008
Abstract Purpose The aim of the study was to compare the influence of different reconstruction algorithms on quantitative emphysema analysis in patients with severe emphysema. Material and methods Twenty-five patients suffering from severe emphysema were included in the study. All patients underwent inspiratory MDCT (Aquilion-16, slice thickness 1/0.8 mm). The raw data were reconstructed using six different algorithms: bone kernel with beam hardening correction (BHC), soft tissue kernel with BHC; standard soft tissue kernel, smooth soft tissue kernel (internal reference standard), standard lung kernel, and high-convolution kernel. The only difference between image data sets was the algorith…