968 resultados para Constant amplitude


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The incidence of contralateral breast cancer is high and constant with age, around five per 1000 women who had a primary breast cancer. For other neoplasms, the pattern of incidence of second primary neoplasms with age is less known, particularly as for only a few neoplasms the site of origin is not totally removed, and hence remains at risk of a second primary. Using the dataset from the Cancer Registry of the Swiss Canton of Vaud, we show that the incidence of second neoplasms is constant with age also after oral and pharyngeal, colorectal cancers, cutaneous malignant melanoma (CMM) and basal cell carcinoma. The incidence of first primary oral and pharyngeal cancer increased 20-fold between age 30-39 and 70-89 years, whereas the incidence of second neoplasms did not increase with age. Rates of second colorectal cancer remained relatively constant with age, between 2.5 per 1000 at age 40-59 years and 3.8 per 1000 at 70 years and above. Likewise, for CMM, the age-specific incidence rates of second primary CMM did not vary, ranging between 1 and 2.5 per 1000 in various subsequent age groups. The pattern of incidence for second basal cell carcinoma was similar, with no clear rise with age. These patterns are compatible with the occurrence of a single mutational event in a population of susceptible individuals. A possible implication of these observations is that a variable, but potentially large, proportion of cancers arise in very high-risk individuals and the incidence, on average, increases at a high constant level at a predetermined age.

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Background: Maturation of amplitude-integrated electroencephalogram (aEEG) activity is influenced by both gestational age (GA) and postmenstrual age. It is not fully known how this process is influenced by cerebral lesions. Objective: To compare early aEEG developmental changes between preterm newborns with different degrees of cerebral lesions on cranial ultrasound (cUS). Methods: Prospective cohort study on preterm newborns with GA <32.0 weeks, undergoing continuous aEEG recording during the first 84 h after birth. aEEG characteristics were qualitatively and quantitatively evaluated using pre-established criteria. Based on cUS findings three groups were formed: normal (n = 78), mild (n = 20), and severe cerebral lesions (n = 6). Linear mixed models for repeated measures were used to analyze aEEG maturational trajectories. Results: 104 newborns with a mean GA (range) 29.5 (24.4-31.7) weeks, and birth weight 1,220 (580-2,020) g were recruited. Newborns with severe brain lesions started with similar aEEG scores and tendentially lower aEEG amplitudes than newborns without brain lesions, and showed a slower development of the cyclic activity (p < 0.001), but a more rapid increase of the maximum and minimum aEEG amplitudes (p = 0.002 and p = 0.04). Conclusions: Preterm infants with severe cerebral lesions manifest a maturational delay in the aEEG cyclic activity already early after birth, but show a catch-up of aEEG amplitudes to that of newborns without cerebral lesions. Changes in the maturational aEEG pattern may be a marker of severe neurological lesions in the preterm infant.

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Patients who had a colorectal cancer have a 1.5- to 2-fold excess risk of a second colorectal cancer as compared to the general population, the excess being higher at younger age at diagnosis. To further investigate the risk and the age-relation of the incidence of second primary colorectal cancer, we considered 9,389 first colon and rectal cancers registered in the Vaud Cancer Registry, Switzerland, between 1974 and 2008, and followed-up to the end of 2008 for a total of 44,113 person-years. There were 136 second colorectal cancers versus 90.5 expected, corresponding to a standardized incidence ratio (SIR) of 1.5 (95% confidence interval, CI, 1.3-1.8). The SIRs were not heterogeneous between men and women, and in strata of calendar year at diagnosis, duration of follow-up, and subsite. However, the SIR was 7.5 (95% CI 4.2-12.4) for subjects diagnosed below age 50 and declined thereafter to reach 1.0 (95% CI 0.6-1.6) at age 80 or over. Consequently, the incidence of second primary colorectal cancer was stable, and exceedingly high, around 300-400/100,000 between age 30-39 and 70 or over. This age pattern is consistent with the existence of a single mutational event in a population of highly susceptible individuals.

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Josep Aragay i Blanchar (Barcelona, 1889 – Breda, 1973) ha estat un personatge clau dins l’art català contemporani i un dels més rellevants del panorama cultural del noucentisme. Aragay va ser dibuixant, gravador, pintor i ceramista, però també fou poeta, professor i polític, i va exercir com a crític, polemista i teòric de l’art

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We analyse the variations produced on tsunami propagation and impact over a straight coastline because of the presence of a submarine canyon incised in the continental margin. For ease of calculation we assume that the shoreline and the shelf edge are parallel and that the incident wave approaches them normally. A total of 512 synthetic scenarios have been computed by combining the bathymetry of a continental margin incised by a parameterised single canyon and the incident tsunami waves. The margin bathymetry, the canyon and the tsunami waves have been generated using mathematical functions (e.g. Gaussian). Canyon parameters analysed are: (i) incision length into the continental shelf, which for a constant shelf width relates directly to the distance from the canyon head to the coast, (ii) canyon width, and (iii) canyon orientation with respect to the shoreline. Tsunami wave parameters considered are period and sign. The COMCOT tsunami model from Cornell University was applied to propagate the waves across the synthetic bathymetric surfaces. Five simulations of tsunami propagation over a non-canyoned margin were also performed for reference. The analysis of the results reveals a strong variation of tsunami arrival times and amplitudes reaching the coastline when a tsunami wave travels over a submarine canyon, with changing maximum height location and alongshore extension. In general, the presence of a submarine canyon lowers the arrival time to the shoreline but prevents wave build-up just over the canyon axis. This leads to a decrease in tsunami amplitude at the coastal stretch located just shoreward of the canyon head, which results in a lower run-up in comparison with a non-canyoned margin. Contrarily, an increased wave build-up occurs on both sides of the canyon head, generating two coastal stretches with an enhanced run-up. These aggravated or reduced tsunami effects are modified with (i) proximity of the canyon tip to the coast, amplifying the wave height, (ii) canyon width, enlarging the areas with lower and higher maximum height wave along the coastline, and (iii) canyon obliquity with respect to the shoreline and shelf edge, increasing wave height shoreward of the leeward flank of the canyon. Moreover, the presence of a submarine canyon near the coast produces a variation of wave energy along the shore, eventually resulting in edge waves shoreward of the canyon head. Edge waves subsequently spread out alongshore reaching significant amplitudes especially when coupling with tsunami secondary waves occurs. Model results have been groundtruthed using the actual bathymetry of Blanes Canyon area in the North Catalan margin. This paper underlines the effects of the presence, morphology and orientation of submarine canyons as a determining factor on tsunami propagation and impact, which could prevail over other effects deriving from coastal configuration.

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Although numerous positron emission tomography (PET) studies with (18) F-fluoro-deoxyglucose (FDG) have reported quantitative results on cerebral glucose kinetics and consumption, there is a large variation between the absolute values found in the literature. One of the underlying causes is the inconsistent use of the lumped constants (LCs), the derivation of which is often based on multiple assumptions that render absolute numbers imprecise and errors hard to quantify. We combined a kinetic FDG-PET study with magnetic resonance spectroscopic imaging (MRSI) of glucose dynamics in Sprague-Dawley rats to obtain a more comprehensive view of brain glucose kinetics and determine a reliable value for the LC under isoflurane anaesthesia. Maps of Tmax /CMRglc derived from MRSI data and Tmax determined from PET kinetic modelling allowed to obtain an LC-independent CMRglc . The LC was estimated to range from 0.33 ± 0.07 in retrosplenial cortex to 0.44 ± 0.05 in hippocampus, yielding CMRglc between 62 ± 14 and 54 ± 11 μmol/min/100 g, respectively. These newly determined LCs for four distinct areas in the rat brain under isoflurane anaesthesia provide means of comparing the growing amount of FDG-PET data available from translational studies.