Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 24
Filter
4.
Chaos ; 24(2): 024404, 2014 Jun.
Article in English | MEDLINE | ID: mdl-24985458

ABSTRACT

Many sleep centres try to perform a reduced portable test in order to decrease the number of overnight polysomnographies that are expensive, time-consuming, and disturbing. With some limitations, heart rate variability (HRV) has been useful in this task. The aim of this investigation was to evaluate if inclusion of symbolic dynamics variables to a logistic regression model integrating clinical and physical variables, can improve the detection of subjects for further polysomnographies. To our knowledge, this is the first contribution that innovates in that strategy. A group of 133 patients has been referred to the sleep center for suspected sleep apnea. Clinical assessment of the patients consisted of a sleep related questionnaire and a physical examination. The clinical variables related to apnea and selected in the statistical model were age (p < 10(-3)), neck circumference (p < 10(-3)), score on a questionnaire scale intended to quantify daytime sleepiness (p < 10(-3)), and intensity of snoring (p < 10(-3)). The validation of this model demonstrated an increase in classification performance when a variable based on non-linear dynamics of HRV (p < 0.01) was used additionally to the other variables. For diagnostic rule based only on clinical and physical variables, the corresponding area under the receiver operating characteristic (ROC) curve was 0.907 (95% confidence interval (CI) = 0.848, 0.967), (sensitivity 87.10% and specificity 80%). For the model including the average of a symbolic dynamic variable, the area under the ROC curve was increased to 0.941 (95% = 0.897, 0.985), (sensitivity 88.71% and specificity 82.86%). In conclusion, symbolic dynamics, coupled with significant clinical and physical variables can help to prioritize polysomnographies in patients with a high probability of apnea. In addition, the processing of the HRV is a well established low cost and robust technique.


Subject(s)
Heart Rate/physiology , Sleep Apnea, Obstructive/diagnosis , Sleep Apnea, Obstructive/physiopathology , Adolescent , Adult , Aged , Aged, 80 and over , Confidence Intervals , Databases as Topic , Electrocardiography , Female , Humans , Logistic Models , Male , Middle Aged , Multivariate Analysis , Nonlinear Dynamics , ROC Curve , Sleep Apnea, Obstructive/diagnostic imaging , Surveys and Questionnaires , Ultrasonography , Young Adult
5.
Phys Rev Lett ; 87(27 Pt 1): 273002, 2001 Dec 31.
Article in English | MEDLINE | ID: mdl-11800876

ABSTRACT

Photoionization of multiply charged ions of the Ba isonuclear sequence up to Ba6+ has been studied in a beam-beam experiment. A very strong increase in the resonance structures was observed when moving from Ba2+ to Ba6+. Absolute values of the photoionization cross sections were measured for Ba2+ and Ba3+ ions. The interpretation of the results is provided using theoretical multiconfiguration Dirac-Fock and relativistic random phase approximation calculations, showing that the collapse of the nf orbitals occurs for Ba4+.

6.
Phys Rev Lett ; 84(3): 435-8, 2000 Jan 17.
Article in English | MEDLINE | ID: mdl-11015932

ABSTRACT

Photoionization of Xe4+ to Xe7+ ions was studied by combining an electron cyclotron resonance ion source with synchrotron radiation. Multiconfiguration Dirac-Fock calculations were performed to interpret the data. Many autoionization lines were measured and identified, resulting from excitation of a 4d electron into nf and np orbitals followed by Auger decay of the excited states. Continuum photoionization is negligible for the higher members of the isonuclear series.

7.
Theor Appl Genet ; 84(5-6): 693-7, 1992 Aug.
Article in English | MEDLINE | ID: mdl-24201359

ABSTRACT

Muskmelon yellowing disease was one of the most serious problems affecting muskmelon crops along the south-east coast of Spain throughout the 1980s. The causal agent of this disease is a virus that we call muskmelon yellows virus (MYV); MYV is transmitted by the greenhouse whitefly Trialeurodes vaporariorum Westwood. It has proven impossible to find sources of resistance to MYV within a wide collection of Spanish muskmelon landraces and exotic varieties. However, 'Nagata Kin Makuwa' and PI 161375, lines of Asiatic origin, show tolerance to this disease. These two lines were studied together with two others ('Galia' and 'Piel de Sapo' type) that are very susceptible to MYV. The crosses between them (susceptible x tolerant) and the segregant generations derived from these crosses were also investigated. The studies were carried out in two different places and years. The expression of tolerance is influenced by the environment. A parabolic type relationship exists between the average value of percentage of tolerant plants and their variation. This allowed us to quantify the expected response in the segregant generations. The results observed in these generations agreed with a simple genetic control of tolerance. This tolerance, combined with protective measures which delay the infection, can contribute notably to mitigating the effects of MYV.

18.
Appl Opt ; 25(20): 3640-4, 1986 Oct 15.
Article in English | MEDLINE | ID: mdl-20454016

ABSTRACT

Recent sputtering techniques have been used to produce layered synthetic microstructures (LSMs) as dispersing devices for varied applications in x-ray optics and spectroscopy. These analyzers, specially suited for synchrotron radiation, have been mounted in a two-parallel crystal monochromator. In this paper we show the first experimental results obtained with beryl crystals and multilayers for analyzing x-ray spectral distributions transmitted through screens or reflected on mirrors of copper near the L(2) and L(3) absorption edges. The significance of these findings is discussed in terms of comparison with natural and synthetic crystals and of designing a useful dispersing device for x-ray spectroscopy.

SELECTION OF CITATIONS
SEARCH DETAIL
...