759 research outputs found

    Characteristics of visual evoked potentials related to the electro-clinical expression of reflex seizures in photosensitive patients with idiopathic occipital lobe epilepsy

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    Seizures provoked by visual stimuli may be induced by abnormal responses to light (photosensitivity) and structured patterns (patternsensitivity). In this study, we analysed visual evoked potentials (VEPs) in three different samples: i) 38 photosensitive patients (21 males, 17 females; mean age 10.0 ± 2.9 years) with idiopathic occipital lobe epilepsy and reflex seizures (RS); ii) 13 non-photosensitive patients (6 males, 7 females; mean age 11.7 ± 5.3) with idiopathic occipital lobe epilepsy; 20 healthy controls (12 males, 8 females; mean age 10.0 ± 3.4). After written informed consent, all subjects underwent a standard procedure of visual stimulation with intermittent light and pattern stimulation, under digital video-EEG recording. The EEG signal was processed off-line by averaging analysis for each stimulus to obtain the corresponding VEP. Comparisons among groups showed no significant differences for P100 latency. Higher P100 amplitude as well as higher after-discharge (AD) were found in photosensitive patients with RS. Thirty-seven of these patients had one or more RS during the procedure of stimulation for a total of 66 episodes. Significant increases of P100 amplitude and higher values of AD amplitude were found in relation to the occurrence of photoparoxysmal response (PPR) and/or seizures during full-field pattern stimulation. The increase in amplitude of the AD was higher when PPR was associated with seizures. The high amplitude of early VEP components confirms the abnormal hyperexcitability in the cortex of photosensitive patients with occipital lobe epilepsy. Moreover, the AD amplitude appears to be related to electro-clinical expression, being greater when PPR evolves into clinically evident seizures

    The use of IASI data to identify systematic errors in the ECMWF forecasts of temperature in the upper stratosphere

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    Since data from the Infrared Atmospheric Sounding Interferometer (IASI) became available in 2007, a number of papers have appeared in the literature which have reported relatively large discrepancies between IASI spectra and forward calculations in the centre of the CO<sub>2</sub> Q-branch at 667 cm<sup>−1</sup>. In this paper we show that these discrepancies are primarily due to errors in the temperature profiles used in the forward calculations. In particular, we have used forecasts of temperature profiles from the European Centre for Medium-Range Weather Forecasts (ECMWF) to demonstrate that, for the case study considered in this paper, these profiles are affected by systematic errors of the order of ≈10 K at the level of the stratopause. To derive the magnitude and the spatial location of the systematic errors in the temperature profile, we have carried out forward/inverse calculations for a number of clear-sky, daytime, IASI tropical soundings over the sea. The forward calculations have been performed using atmospheric state vectors which have been obtained either from the direct inversion of the IASI radiances or from space-time co-located profiles derived from radiosonde observations and from the ECMWF model. To rule out any effect due to the accuracy of the forward model, we have performed the forward calculations using two independent models. The sensitivity of the temperature biases to the variability of the CO<sub>2</sub> profile and to spectroscopy errors has also been studied

    The detection of post-monsoon tropospheric ozone variability over south Asia using IASI data

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    The ozone (O<sub>3</sub>) variability over south Asia during the 2008 post-monsoon season has been assessed using measurements from the MetOP-A/IASI instrument and O<sub>3</sub> profiles retrieved with the SOftware for a Fast Retrieval of IASI Data (SOFRID). The information content study and error analyses carried out in this paper show that IASI Level 1 data can be used to retrieve tropospheric O<sub>3</sub> columns (TOC, surface-225 hPa) and UTLS columns (225–70 hPa) with errors smaller than 20%. Validation with global radiosonde O<sub>3</sub> profiles obtained during a period of 6 months show the excellent agreement between IASI and radiosonde for the UTLS with correlation coefficient <i>R</i> > 0.91 and good agreement in the troposphere with correlation coefficient <i>R</i> > 0.74. For both the UTLS and the troposphere Relative Standard Deviations (RSD) are lower than 23%. Comparison with in-situ measurements from the MOZAIC program around Hyderabad demonstrates that IASI is able to capture the TOC inter and intra-seasonal variability in central India. Nevertheless, the agreement is mitigated by the fact that the smoothing of the true O<sub>3</sub> profiles by the retrieval results in a reduction of the TOC variability detected by IASI relative to the variability observed by in situ instruments. The post-monsoon temporal variability of the vertical profile of O<sub>3</sub> around Hyderabad has been investigated with MOZAIC observations. These observations from airborne instruments show that tropospheric O<sub>3</sub> is steadily elevated during most of the studied period with the exception of two sharp drops following the crossing of tropical storms over India. Lagrangian simulations with the FLEXPART model indicate that elevated O<sub>3</sub> concentrations in the middle troposphere near Hyderabad are associated with the transport of UTLS air-masses that have followed the Subtropical Westerly Jet (SWJ) and subsided over northern India together with boundary layer polluted air-masses transported from the Indo-gangetic plain by the north-easterly trades. Low O<sub>3</sub> concentrations result from the uplift and westward transport of pristine air-masses from the marine boundary layer of the Bay of Bengal by tropical storms. In order to extend the analysis of tropospheric O<sub>3</sub> variability to the whole of south Asia, we have used IASI-SOFRID O<sub>3</sub> data. We show that IASI O<sub>3</sub> data around Hyderabad were able to capture the fast variability revealed by MOZAIC. Furthermore, their spatio-temporal coverage demonstrates that the behaviour of tropospheric O<sub>3</sub> observed near Hyderabad extended over most of central and south India and part of the Bay of Bengal. This result highlights the ability of the IASI sensor to capture fast changes in chemical composition related to dramatic tropical weather conditions

    Technical note: Functional sliced inverse regression to infer temperature, water vapour and ozone from IASI data.

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    A retrieval algorithm that uses a statistical strategy based on dimension reduction is proposed. The methodology and details of the implementation of the new algorithm are presented and discussed. The algorithm has been applied to high resolution spectra measured by the Infrared Atmospheric Sounding Interferometer instrument to retrieve atmospheric profiles of temperature, water vapour and ozone. The performance of the inversion strategy has been assessed by comparing the retrieved profiles to the ones obtained by co-locating in space and time profiles from the European Centre for Medium-Range Weather Forecasts analysi

    A study of longitudinal mobile health data through fuzzy clustering methods for functional data: The case of allergic rhinoconjunctivitis in childhood

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    The use of mobile communication devices in health care is spreading worldwide. A huge amount of health data collected by these devices (mobile health data) is nowadays available. Mobile health data may allow for real-time monitoring of patients and delivering ad-hoc treatment recommendations. This paper aims at showing how this may be done by exploiting the potentialities of fuzzy clustering techniques. In fact, such techniques can be fruitfully applied to mobile health data in order to identify clusters of patients for diagnostic classification and cluster-specific therapies. However, since mobile health data are full of noise, fuzzy clustering methods cannot be directly applied to mobile health data. Such data must be denoised prior to analyzing them. When longitudinal mobile health data are available, functional data analysis represents a powerful tool for filtering out the noise in the data. Fuzzy clustering methods for functional data can then be used to determine groups of patients. In this work we develop a fuzzy clustering method, based on the concept of medoid, for functional data and we apply it to longitudinal mHealth data on daily symptoms and consumptions of anti-symptomatic drugs collected by two sets of patients in Berlin (Germany) and Ascoli Piceno (Italy) suffering from allergic rhinoconjunctivitis. The studies showed that clusters of patients with similar changes in symptoms were identified opening the possibility of precision medicine

    FORMAS ZOOARIALES EN EL DESARROLLO DE UNA COMUNIDAD DE BRIOZOOS

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    The dynamics of the relations between different zoarial forms of cheilostome bryozoans, during the development of a community on artificial substrates, have been studied along an infralittoral cliff of the northwestem Mediterranean Sea. Membraniporiform bryozoans (thick membraniporiform and thin membraniporiform zoarial types) prevail during the first stages of colonization. Later, at shallow depth, erect flexible forms (tuft-like zoarial type) tend to increase prevailing over the encrusting ones and, at greater depth, membraniporiform colonies continue to play a major role. The studied zoarial types show differences both in their ability to settle and to grow on bare and smooth surfaces and on substrate occupied by other organisms, and also to adjust to modifications of the substrate through time. The variations in the relative abundance of different zoarial forms correspond to changes in the availability of primary space and to new ecological conditions close to the substrate surface.Se ha estudiado la dinámica de las relaciones entre diversas formas zoariales de Briozoos Cheilostomata durante la evolución de una comunidad sobre sustrato artificial a lo largo de un acantilado infralitoral del Mediterráneo nord-occidental. Los briozoos membraniporiformes caracterizan las primeras fases de colonización. En seguida en las zonas más superficiales, las formas erectas y flexibles aumentan notablemente y tienden a prevalecer sobre las formas incrustantes. En las áreas más profundas en cambio, las colonias membraniporiformes siguen siendo predominantes. Los diversos tipos zoariales que se han considerado, presentan grandes diferencias por lo que respecta, ya sea a la capacidad de fijarse y crecer sobre superficies desnudas y lisas o sobre substratos ocupados por otros organismos, ya sea la posibilidad de adaptarse a las variaciones que sufre el substrato en el transcurso del tiempo. Las variaciones en la abundancia relativa de los diversos tipos morfológicos está correlacionada con la disminución del espacio primario y, por lo tanto, con las nuevas condiciones ecológicas a nivel de las supeficies del sustrato

    Relapse risk factors in anti-N-methyl-D-aspartate receptor encephalitis

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    Aim: To identify factors that may predict and affect the risk of relapse in anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis. Method: This was a retrospective study of an Italian cohort of patients with paediatric (≤18y) onset anti-NMDAR encephalitis. Results: Of the 62 children included (39 females; median age at onset 9y 10mo, range 1y 2mo–18y; onset between 2005 and 2018), 21 per cent relapsed (median two total events per relapsing patient, range 2–4). Time to first relapse was median 31.5 months (range 7–89mo). Severity at first relapse was lower than onset (median modified Rankin Scale [mRS] 3, range 2–4, vs median mRS 5, range 3–5; admission to intensive care unit: 0/10 vs 3/10). At the survival analysis, the risk of relapsing was significantly lower in patients who received three or more different immune therapies at first disease event (hazard ratio 0.208, 95% confidence interval 0.046–0.941; p=0.042). Neurological outcome at follow-up did not differ significantly between patients with relapsing and monophasic disease (mRS 0–1 in 39/49 vs 12/13; p=0.431), although follow-up duration was significantly longer in relapsing (median 84mo, range 14–137mo) than in monophasic patients (median 32mo, range 4–108mo; p=0.002). Interpretation: Relapses may occur in about one-fifth of children with anti-NMDAR encephalitis, are generally milder than at onset, and may span over a long period, although they do not seem to be associated with severity in the acute phase or with outcome at follow-up. Aggressive immune therapy at onset may reduce risk of relapse. What this paper adds: Relapses of anti-N-methyl-D-aspartate receptor encephalitis may span over a long period. Relapses were not associated with severity in the acute phase or outcome at follow-up. Aggressive immune therapy at onset appears to decrease risk of relapse

    Unraveling the enigma of new-onset refractory status epilepticus: a systematic review of aetiologies

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    Background and purpose: New-onset refractory status epilepticus (NORSE) is a clinical presentation, neither a specific diagnosis nor a clinical entity. It refers to a patient without active epilepsy or other pre-existing relevant neurological disorder, with a NORSE without a clear acute or active structural, toxic or metabolic cause. This study reviews the currently available evidence about the aetiology of patients presenting with NORSE and NORSE-related conditions. Methods: A systematic search was carried out for clinical trials, observational studies, case series and case reports including patients who presented with NORSE, febrile-infection-related epilepsy syndrome or the infantile hemiconvulsion-hemiplegia and epilepsy syndrome. Results: Four hundred and fifty records were initially identified, of which 197 were included in the review. The selected studies were retrospective case–control (n = 11), case series (n = 83) and case reports (n = 103) and overall described 1334 patients both of paediatric and adult age. Aetiology remains unexplained in about half of the cases, representing the so-called ‘cryptogenic NORSE’. Amongst adult patients without cryptogenic NORSE, the most often identified cause is autoimmune encephalitis, either non-paraneoplastic or paraneoplastic. Infections are the prevalent aetiology of paediatric non-cryptogenic NORSE. Genetic and congenital disorders can have a causative role in NORSE, and toxic, vascular and degenerative conditions have also been described. Conclusions: Far from being a unitary condition, NORSE is a heterogeneous and clinically challenging presentation. The development and dissemination of protocols and guidelines to standardize diagnostic work-up and guide therapeutic approaches should be implemented. Global cooperation and multicentre research represent priorities to improve the understanding of NORSE

    Guar gum/borax hydrogel: Rheological, low field NMR and release characterizations

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    Guar gum (GG) and Guar gum/borax (GGb) hydrogels are studied by means of rheology, Low Field Nuclear Magnetic Resonance (LF NMR) and model drug release tests. These three approaches are used to estimate the mesh size (ζ) of the polymeric network. A comparison with similar Scleroglucan systems is carried out. In the case of GGb, the rheological and Low Field NMR estimations of ζ lead to comparable results, while the drug release approach seems to underestimate ζ. Such discrepancy is attributed to the viscous effect of some polymeric chains that, although bound to the network to one end, can freely fluctuate among meshes. The viscous drag exerted by these chains slows down drug diffusion through the polymeric network. A proof for this hypothesis is given by the case of Scleroglucan gel, where the viscous contribution is not so significant and a good agreement between the rheological and release test approaches was found
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