George Sudarshan Volume 31, Issue 1, Pages 1-406(15 September 1999)
Preface
Preface
NASA Astrophysics Data System (ADS)
Oden, J. T.; Prudhomme, S.
1999-09-01
We present a new approach to deliver reliable approximations of the norm of the residuals resulting from finite element solutions to the Stokes and Oseen equations. The method is based upon a global solve in a bubble space using iterative techniques. This provides an alternative to the classical equilibrated element residual methods for which it is necessary to construct proper boundary conditions for each local problem. The method is first used to develop a global a posteriori error estimator. It is then applied in a strategy to control the numerical error in specific outputs or quantities of interest which are functions of the solutions to the Stokes and Oseen equations. Copyright
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Volume 39, Issue 9, Pages 763-864(30 July 2002)
Research Article
Embedded turbulence model in numerical methods for hyperbolic conservation laws
NASA Astrophysics Data System (ADS)
Drikakis, D.
2002-07-01
The paper describes the use of numerical methods for hyperbolic conservation laws as an embedded turbulence modelling approach. Different Godunov-type schemes are utilized in computations of Burgers' turbulence and a two-dimensional mixing layer. The schemes include a total variation diminishing, characteristic-based scheme which is developed in this paper using the flux limiter approach. The embedded turbulence modelling property of the above methods is demonstrated through coarsely resolved large eddy simulations with and without subgrid scale models. Copyright
Travellers' diarrhoea-a survey of practice.
McGrath, Christian M; Leder, Karin
2017-03-01
Travellers' diarrhoea (TD) is a common problem, affecting millions of tourists each year and creating a large economic burden. Risk factors for TD are known and guidelines exist to assist practitioners in advising travellers on how to prevent and treat TD. However, data are lacking regarding actual prescribing practices or approaches used in TD management. This study aims to establish a baseline which identifies uniformities and diversities in practice. An online survey created using the SurveyMonkey tool was developed to test respondent approaches to TD pre-travel management. An invitation to participate in the survey was distributed early 2016 through selected Australian and New Zealand speciality travel medicine centres and through the electronic mailing list of the International Society of Travel Medicine (ISTM). Descriptive statistics and analyses using Chi Square analysis and two-sided Fishers exact tests for significance were used. Three hundred and sixty-four completed or partially completed surveys were collected from respondents in 23 countries. Approach to TD, antibiotic choice and management of four different clinical scenarios were assessed, with analyses focused on identifying significant differences in approach according to region of practice, professional background and level of experience. The responses to the clinical scenarios suggest most uniformity in recommended treatment strategies in clearly mild or severe disease, and greater variability in moderate disease. There is practice diversity in the discussion of preventative techniques and prescribing of self-treatment medications for TD, especially for moderate TD disease. Evidence-based guidelines that address the competing issues of patient health and morbidity vs the risk of colonization with resistant organisms may lead to more consistent antibiotic prescribing practices. © International Society of Travel Medicine, 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com
DOE Office of Scientific and Technical Information (OSTI.GOV)
Nishimoto, Yoshio, E-mail: nishimoto.yoshio@fukui.kyoto-u.ac.jp
2015-09-07
We develop a formalism for the calculation of excitation energies and excited state gradients for the self-consistent-charge density-functional tight-binding method with the third-order contributions of a Taylor series of the density functional theory energy with respect to the fluctuation of electron density (time-dependent density-functional tight-binding (TD-DFTB3)). The formulation of the excitation energy is based on the existing time-dependent density functional theory and the older TD-DFTB2 formulae. The analytical gradient is computed by solving Z-vector equations, and it requires one to calculate the third-order derivative of the total energy with respect to density matrix elements due to the inclusion of themore » third-order contributions. The comparison of adiabatic excitation energies for selected small and medium-size molecules using the TD-DFTB2 and TD-DFTB3 methods shows that the inclusion of the third-order contributions does not affect excitation energies significantly. A different set of parameters, which are optimized for DFTB3, slightly improves the prediction of adiabatic excitation energies statistically. The application of TD-DFTB for the prediction of absorption and fluorescence energies of cresyl violet demonstrates that TD-DFTB3 reproduced the experimental fluorescence energy quite well.« less
Deformation and annealing response of TD-nickel chromium sheet
NASA Technical Reports Server (NTRS)
Kane, R. D.; Ebert, L. J.
1973-01-01
The deformation and annealing response of TD-nickel chromium (TD-NiCr) 0.1 inch thick sheet was examined using various cold-rolling and annealing treatments. Upon annealing (above 816 C (1500 F), the as-received material was converted from an initially ultra-fine grain size (average grain dimension 0.51 micron) to a large grain structure. Increases in grain size by a factor of 100 to 200 were observed for this transformation. However, in those material states where the large grain transformation was absent, a fine grain recrystallized structure formed upon annealing (above 732 C (1350 F)). The deformation and annealing response of TD-NiCr sheet was evaluated with respect to the processing related variables as mode and severity of deformation and annealing temperature. Results indicate that the large grain transformation, classical primary recrystallization occurs. Using selected materials produced during the deformation and annealing study, the elevated temperature tensile properties of TD-NiCr sheet were examined in the temperature range 593 C (1100 F) to 1093 C (2000 F). It was observed that the elevated temperature tensile properties of TD-NiCr sheet could be optimized by the stabilization of a large grain size in this material using the cold working and/or annealing treatments developed during the present investigation.
Isomura, Tomoko; Ogawa, Shino; Yamada, Satoko; Shibasaki, Masahiro; Masataka, Nobuo
2014-01-01
Previous studies have demonstrated that angry faces capture humans' attention more rapidly than emotionally positive faces. This phenomenon is referred to as the anger superiority effect (ASE). Despite atypical emotional processing, adults and children with Autism Spectrum Disorders (ASD) have been reported to show ASE as well as typically developed (TD) individuals. So far, however, few studies have clarified whether or not the mechanisms underlying ASE are the same for both TD and ASD individuals. Here, we tested how TD and ASD children process schematic emotional faces during detection by employing a recognition task in combination with a face-in-the-crowd task. Results of the face-in-the-crowd task revealed the prevalence of ASE both in TD and ASD children. However, the results of the recognition task revealed group differences: In TD children, detection of angry faces required more configural face processing and disrupted the processing of local features. In ASD children, on the other hand, it required more feature-based processing rather than configural processing. Despite the small sample sizes, these findings provide preliminary evidence that children with ASD, in contrast to TD children, show quick detection of angry faces by extracting local features in faces. PMID:24904477
Nishimoto, Yoshio
2015-09-07
We develop a formalism for the calculation of excitation energies and excited state gradients for the self-consistent-charge density-functional tight-binding method with the third-order contributions of a Taylor series of the density functional theory energy with respect to the fluctuation of electron density (time-dependent density-functional tight-binding (TD-DFTB3)). The formulation of the excitation energy is based on the existing time-dependent density functional theory and the older TD-DFTB2 formulae. The analytical gradient is computed by solving Z-vector equations, and it requires one to calculate the third-order derivative of the total energy with respect to density matrix elements due to the inclusion of the third-order contributions. The comparison of adiabatic excitation energies for selected small and medium-size molecules using the TD-DFTB2 and TD-DFTB3 methods shows that the inclusion of the third-order contributions does not affect excitation energies significantly. A different set of parameters, which are optimized for DFTB3, slightly improves the prediction of adiabatic excitation energies statistically. The application of TD-DFTB for the prediction of absorption and fluorescence energies of cresyl violet demonstrates that TD-DFTB3 reproduced the experimental fluorescence energy quite well.
Preskorn, Sheldon H; Macaluso, Matthew
2016-03-01
This series of columns has 3 main goals: (1) to explain class warnings as used by the United States Food and Drug Administration, (2) to increase awareness of movement disorders that may occur in patients treated with antipsychotic medications, and (3) to understand why clinicians should refrain from immediately assuming a diagnosis of tardive dyskinesia/dystonia (TD) in patients who develop abnormal movements during treatment with antipsychotics. The first column in the series presented a patient who developed abnormal movements while being treated with aripiprazole as an augmentation strategy for major depressive disorder (MDD) and reviewed data concerning the historical background, incidence, prevalence, and risk factors for tardive and spontaneous dyskinesias, the clinical presentations of which closely resemble each other. The second column in the series reviewed the unique mechanism of action of aripiprazole and preclinical studies and an early-phase human translational study that suggest a low, if not absent, risk of TD with aripiprazole. This column reviews clinical trial data to assess whether those data support the conclusion that aripiprazole has a low to absent risk of causing TD when used as an augmentation strategy to treat MDD. To date, no randomized, placebo-controlled trials have established a definitive link between exposure to aripiprazole and TD in patients with MDD. One long-term, open-label, safety trial examined aripiprazole as an augmentation strategy in individuals with MDD and found a rare occurrence (4/987, 0.4%, the confidence interval of which overlaps with zero) of an adverse event termed TD. In all 4 cases, the observed movements resolved within weeks of aripiprazole discontinuation, suggesting that they were either amenable to treatment or represented an acute syndrome rather than TD. No cases of TD were reported in the registration trials for the MDD indication for aripiprazole. These data were presented in a pooled analysis of three, 14-week studies involving 1088 subjects, 409 of whom were elderly like the 76-year-old individual presented in the case in the first column of this series. Finally, 3 short-term studies evaluated the use of aripiprazole in patients with psychosis associated with Alzheimer disease, a population who would be considered a relatively higher risk group for developing TD when exposed to antipsychotics and that also closely matches the patient in the case presented at the beginning of this series in terms of age. No incidence of TD was reported in this sample and mean scores on the Abnormal Involuntary Movement Scale decreased in individuals exposed to aripiprazole compared with those on placebo. On the basis of results of this review and data from registration trials of aripiprazole for all indications, the potential (or raw) incidence of what was termed TD occurred at rates ranging from 0.004 (4/987) based on long-term safety data from the program investigating aripiprazole augmentation treatment in MDD, to 0.0016 (19/11,897) based on the total safety database from aripiprazole registration trials for all indications, to 0 in trials in elderly individuals with Alzheimer disease. The confidence intervals for all of these potential incidence rates overlap with zero. The next column in this 5-part series reviews 37 case reports that reported TD in association with aripiprazole treatment and 27 case reports that suggested an improvement in preexisting TD with aripiprazole treatment. The fifth and final column in this series will discuss the types of prohibitively expensive and logistically difficult studies that would be needed to determine whether a definitive causal relationship between aripiprazole and TD exists.
Zhu, Huilin; Li, Jun; Fan, Yuebo; Li, Xinge; Huang, Dan; He, Sailing
2015-01-01
Autism spectrum disorder (ASD) is a neuro-developmental disorder, characterized by impairments in one’s capacity for joint attention. In this study, functional near-infrared spectroscopy (fNIRS) was applied to study the differences in activation and functional connectivity in the prefrontal cortex between children with autism spectrum disorder (ASD) and typically developing (TD) children. 21 ASD and 20 TD children were recruited to perform joint and non-joint attention tasks. Compared with TD children, children with ASD showed reduced activation and atypical functional connectivity pattern in the prefrontal cortex during joint attention. The atypical development of left prefrontal cortex might play an important role in social cognition defects of children with ASD. PMID:25798296
Typical and atypical neurodevelopment for face specialization: An fMRI study
Joseph, Jane E.; Zhu, Xun; Gundran, Andrew; Davies, Faraday; Clark, Jonathan D.; Ruble, Lisa; Glaser, Paul; Bhatt, Ramesh S.
2014-01-01
Individuals with Autism Spectrum Disorder (ASD) and their relatives process faces differently from typically developed (TD) individuals. In an fMRI face-viewing task, TD and undiagnosed sibling (SIB) children (5–18 years) showed face specialization in the right amygdala and ventromedial prefrontal cortex (vmPFC), with left fusiform and right amygdala face specialization increasing with age in TD subjects. SIBs showed extensive antero-medial temporal lobe activation for faces that was not present in any other group, suggesting a potential compensatory mechanism. In ASD, face specialization was minimal but increased with age in the right fusiform and decreased with age in the left amygdala, suggesting atypical development of a frontal-amygdala-fusiform system which is strongly linked to detecting salience and processing facial information. PMID:25479816
Bair, Woei-Nan; Barela, José A.; Whitall, Jill; Jeka, John J.; Clark, Jane E.
2011-01-01
In two experiments, the ability to use multisensory information (haptic information, provided by lightly touching a stationary surface, and vision) for quiet standing was examined in typically developing (TD) children, adults, and in 7-year-old children with Developmental Coordination Disorder (DCD). Four sensory conditions (no touch/no vision, with touch/no vision, no touch/with vision, and with touch/with vision) were employed. In experiment 1, we tested 4-, 6- and 8-year-old TD children and adults to provide a developmental landscape for performance on this task. In experiment 2, we tested a group of 7-year-old children with DCD and their age-matched TD peers. For all groups, touch robustly attenuated standing sway suggesting that children as young as 4 years old use touch information similarly to adults. Touch was less effective in children with DCD compared to their TD peers, especially in attenuating their sway velocity. Children with DCD, unlike their TD peers, also benefited from using vision to reduce sway. The present results suggest that children with DCD benefit from using vision in combination with touch information for standing control possibly due to their less well developed internal models of body orientation and self-motion. Internal model deficits, combined with other known deficits such as postural muscles activation timing deficits, may exacerbate the balance impairment in children with DCD. PMID:21571533
Jacobs, Myrthe; Marks Woolfson, Lisa; Hunter, Simon C
2017-01-01
Children with developmental delays (DD) are at risk for developing behavior problems. Research suggests that parents' causal attributions for child behavior are related to parenting. This study investigated this association in parents of children with DD compared to parents of typically developing (TD) children. It specifically focused on attributions of child control by separating these from attributions of responsibility, blame and intent, and from attributions of parent control and responsibility. Fifty-one parents of children with DD and 69 parents of TD children completed two questionnaires. The Written Analogue Questionnaire measured causal attributions. The Parenting Scale measured dysfunctional discipline practices. Parents of children with DD viewed the child's role in problematic behavior more positively while also viewing misbehavior as more fixed than parents of TD children. Parents of TD children who viewed their child as more in control over misbehavior used less dysfunctional discipline, but this association was not found for parents of children with DD. The results advance understanding of how parents perceive behavior problems in children with DD and the important role these perceptions play in parental behavior management strategies. More importantly, these perceptions relate to discipline practices differently for parents of children with DD compared to parents of TD children, highlighting that parent interventions should be adapted to the specific needs of parents of children with DD.
Savareear, Benjamin; Brokl, Michał; Wright, Chris; Focant, Jean-Francois
2017-11-24
A thermal desorption comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (TD-GC×GC-TOFMS) method has been developed for the analysis of mainstream tobacco smoke (MTS) vapour phase (VP). The selection process of the sample introduction approach involved comparing the results obtained from three different approaches: a) use of gas sampling bag followed by SPME (Tedlar ® -SPME), b) gas sampling bag followed by TD (Tedlar ® -TD), and c) sampling directly on TD sorbents (Direct-TD). Six different SPME fibers and six different TD sorbent beds were evaluated for the extraction capacities in terms of total number of peaks and related intensities or peak areas. The best results were obtained for the Direct-TD approach using Tenax TA/Carbograph1TD/Carboxen1003 sorbent tubes. The optimisation of TD tube desorption parameters was carried out using a face-centered central composite experimental design and resulted in the use of the Tenax TA/Carbograph 1TD/Carboxen 1003 sorbent with a 7.5min desorption time, a 60mL/min tube desorption flow, and a 250°C tube desorption temperature. The optimised method was applied to the separation of MTS-VP constituents, with 665 analytes detected. The method precision ranged from 1% to 15% for over 99% of identified peak areas and from 0% to 3% and 0% to 1% for both first ( 1 t R ) and second ( 2 t R ) dimension retention times, respectively. The method was applied to the analyses of two cigarette types differing in their filter construction. Principal component analysis (PCA) allowed a clear differentiation of the studied cigarette types (PC1 describing 94% of the explained variance). Supervised Fisher ratio analysis permitted the identification of compounds responsible for the chemical differences between the two sample types. A set of 91 most relevant compounds was selected by applying a Fisher ratio cut-off approach and most of them were selectively removed by one of the cigarette filter types. Copyright © 2017 Elsevier B.V. All rights reserved.
Kovac, Martina; Rathi, Niraj; Kuriyakose, Sherine; Hardt, Karin; Schwarz, Tino F
2015-05-21
Pertussis in adults and adolescents could be reduced by replacing traditional tetanus and diphtheria (Td) boosters with reduced-antigen-content diphtheria-tetanus-acellular pertussis (dTpa) vaccines. This study evaluated the administration of dTpa-IPV (dTpa-inactivated poliovirus) in adults ten years after they received a booster dose of either dTpa-IPV, dTpa+IPV or Td-IPV in trial NCT01277705. Open multicentre, phase IV study (www.clinicaltrials.govNCT01323959) in which healthy adults, who had received a previous dose of dTpa-IPV, dTpa+IPV or Td-IPV ten years earlier, received a single decennial booster dose of dTpa-IPV (Boostrix-polio, GlaxoSmithKline Vaccines). Blood samples were collected before and one month after booster vaccination. Antibody concentrations against all vaccine antigens were measured and reactogenicity and safety were assessed. A total of 211 subjects (mean age 50.3 years) received vaccination of whom 201 were included in the according-to-protocol cohort for immunogenicity. Before the decennial dTpa-IPV booster, ≥71.0% subjects were seroprotected/seropositive against all vaccine antigens. One month after the booster dose, all subjects were seroprotected against tetanus and poliovirus types 2 and 3; ≥95.7% subjects were seroprotected against diphtheria and ≥98.3% against poliovirus type 1. Anti-pertussis booster responses for the various antigens were observed in ≥76.5% (pertussis toxoid; PT), ≥85.1% (filamentous haemagglutinin; FHA) and ≥63.2% (pertactin; PRN) of subjects. During the 4-day follow-up, the overall incidence of local AEs was 71.6%, 75.0% and 72.2% in dTpa-IPV, dTpa+IPV and Td-IPV groups, respectively. Pain was the most frequent solicited local adverse event (AE; ≥62.7% subjects) and fatigue the most frequent solicited general AE (≥18.5%). No serious AEs were reported during the study. A booster dose of dTpa-IPV was immunogenic and well tolerated in adults who had received a booster dose of either dTpa-IPV, dTpa+IPV or Td-IPV, ten years previously and supports the repeated administration of dTpa-IPV. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.
Visual search and emotion: how children with autism spectrum disorders scan emotional scenes.
Maccari, Lisa; Pasini, Augusto; Caroli, Emanuela; Rosa, Caterina; Marotta, Andrea; Martella, Diana; Fuentes, Luis J; Casagrande, Maria
2014-11-01
This study assessed visual search abilities, tested through the flicker task, in children diagnosed with autism spectrum disorders (ASDs). Twenty-two children diagnosed with ASD and 22 matched typically developing (TD) children were told to detect changes in objects of central interest or objects of marginal interest (MI) embedded in either emotion-laden (positive or negative) or neutral real-world pictures. The results showed that emotion-laden pictures equally interfered with performance of both ASD and TD children, slowing down reaction times compared with neutral pictures. Children with ASD were faster than TD children, particularly in detecting changes in MI objects, the most difficult condition. However, their performance was less accurate than performance of TD children just when the pictures were negative. These findings suggest that children with ASD have better visual search abilities than TD children only when the search is particularly difficult and requires strong serial search strategies. The emotional-social impairment that is usually considered as a typical feature of ASD seems to be limited to processing of negative emotional information.
Ng, Rowena; Järvinen, Anna; Bellugi, Ursula
2014-01-01
Previous research has robustly established a Williams syndrome (WS) specific personality profile, predominantly characterized a gregarious, people-oriented, and tense predisposition. Extending this work, the aims of the current, cross-sectional study were two-fold: (1) to elucidate the stability of personality characteristics in individuals with WS and typically developing (TD) comparisons across development, and (2) to explore the personality attributes that may be related to the respective profiles of social functioning characterizing the two groups, which is currently poorly understood. The sample comprised of participants with WS and TD matched on chronological age. The test battery included the Multidimensional Personality Questionnaire (MPQ) and the Salk Institute Sociability Questionnaire (SISQ), an index of real-life social behavior. The main results showed that compared to the TD individuals, the WS group were consistently rated higher in Social Closeness, and this trait remained stable across development. Interpersonal behaviors were best predicted by Social Closeness in WS and by Social Potency in TD. Regression analysis highlighted that while a central motive underlying the increased drive toward social interaction in individuals with WS pertains to a desire to form affectionate relationships, TD individuals by contrast are motivated by a desire to exert social influence over others (leadership, social-dominance) and Well-Being (positive emotional disposition). In conclusion, these findings provide novel insight into social motivational factors underpinning the WS social behavior in real life, and contribute toward a deeper characterization of the WS affiliative drive. We suggest potential areas for behavioral intervention targeting improved social adjustment in individuals with WS. PMID:24794322
López-Pérez, Belén; Ambrona, Tamara; Gummerum, Michaela
2018-02-05
Emotion goals lie at the heart of emotion regulation, as people have to first decide what emotions they want to feel before engaging in emotion regulation. Given that children with Asperger's syndrome (AS) are characterized by exhibiting difficulties in emotion regulation, studying whether they display similar or different emotion goals compared to typically developing (TD) children may provide insightful information. Thirty AS and 30 TD children (10-12 years) reported about their general (i.e., how they want to feel in general) and contextualized (i.e., how they want to feel when confronting vs. collaborating with someone) emotion goals, and about their difficulties in emotion regulation through questionnaires. Results showed that both groups did not differ in their general emotional goals and in their contextualized emotion goals for happiness for collaboration and anger for confrontation. AS children only differed from TD children in a higher preference for sadness for collaboration and happiness for confrontation. These emotion goals predicted their difficulties to engage in goal-directed behaviour. The obtained results support the need to further study emotion goals as an aspect of emotion dysregulation, namely the difficulties to engage in goal-directed behaviour when experiencing different emotions. AS and TD children did not differ in their general emotion goals. AS and TD children did not vary in their preferences for happiness for collaboration and anger for confrontation. AS children only differed in a higher preference for sadness for collaboration and happiness for confrontation. Understanding emotion goals might help practitioners to develop better interventions. © 2018 The British Psychological Society.
Lehmann, David F; Eggleston, William D; Wang, Dongliang
2018-03-01
Use of the QT interval corrected for heart rate (QTc) on the electrocardiogram (ECG) to predict torsades de pointes (TdP) risk from culprit drugs is neither sensitive nor specific. The ratio of the half-maximum inhibitory concentration of the hERG channel (hERG IC50) to the peak serum concentration of unbound drug (C max ) is used during drug development to screen out chemical entities likely to cause TdP. To validate the use of the hERG IC50:C max ratio to predict TdP risk from a culprit drug by its correlation with TdP incidence. Medline (between 1966 and March 2017) was accessed for hERG IC50 and C max values from the antihistamine, fluoroquinolone, and antipsychotic classes to identify cases of drug-induced TdP. Exposure to a culprit drug was estimated from annual revenues reported by the manufacturer. Inclusion criteria for TdP cases were provision of an ECG tracing that demonstrated QTc prolongation with TdP and normal serum values of potassium, calcium, and magnesium. Cases reported in patients with a prior rhythm disturbance and those involving a drug interaction were excluded. The Meta-Analysis of Observational Studies in Epidemiology checklist was used for epidemiological data extraction by two authors. Negligible risk drugs were defined by an hERG IC50:C max ratio that correlated with less than a 5% chance of one TdP event for every 100 million exposures (relative risk [RR] 1.0). The hERG IC50:C max ratio correlated with TdP risk (0.312; 95% confidence interval 0.205-0.476, p<0.0001), a ratio of 80 (RR 1.0). The RR from olanzapine is on par with loratadine; ziprasidone is comparable with ciprofloxacin. Drugs with an RR greater than 50 include astemizole, risperidone, haloperidol, and thioridazine. The hERG IC50:C max ratio was correlated with TdP incidence for culprit drugs. This validation provides support for the potential use of the hERG IC50:C max ratio for clinical decision making in instances of drug selection where TdP risk is a concern. © 2018 Pharmacotherapy Publications, Inc.
Vandersickel, Nele; Bossu, Alexandre; De Neve, Jan; Dunnink, Albert; Meijborg, Veronique M F; van der Heyden, Marcel A G; Beekman, Jet D M; De Bakker, Jacques M T; Vos, Marc A; Panfilov, Alexander V
2017-12-26
This study investigated the arrhythmogenic mechanisms responsible for torsade de pointes (TdP) in the chronic atrioventricular block dog model, known for its high susceptibility for TdP. The mechanism of TdP arrhythmias has been under debate for many years. Focal activity as well as re-entry have both been mentioned in the initiation and the perpetuation of TdP. In 5 TdP-sensitive chronic atrioventricular block dogs, 56 needle electrodes were evenly distributed transmurally to record 240 unipolar local electrograms simultaneously. Nonterminating (NT) episodes were defibrillated after 10 s. Software was developed to automatically detect activation times and to create 3-dimensional visualizations of the arrhythmia. For each episode of ectopic activity (ranging from 2 beats to NT episodes), a novel methodology was created to construct directed graphs of the wave propagation and detect re-entry loops by using an iterative depth-first-search algorithm. Depending on the TdP definition (number of consecutive ectopic beats), we analyzed 29 to 54 TdP: 29 were longer than 5 beats. In the total group, 9 were NT and 45 were self-terminating. Initiation and termination were always based on focal activity. Re-entry becomes more important in the longer-lasting episodes (>14 beats), whereas in all NT TdP, re-entry was the last active mechanism. During re-entry, excitation fronts were constantly present in the heart, while during focal TdP, there was always a silent interval between 2 consecutive waves (142 ms) during which excitation fronts were absent. Interbeat intervals were significantly smaller for re-entry episodes-220 versus 310 ms in focal. Electrograms recorded in particular areas during NT TdP episodes had significantly smaller amplitude (0.38) than during focal episodes (0.59). TdP can be driven by focal activity as well as by re-entry depending on the duration of the episode. NT episodes are always maintained by re-entry, which can be identified in local unipolar electrograms by shorter interbeat intervals and smaller deflection amplitude. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.
Thordardottir, Elin
2016-01-01
Grammatical morphology continues to be widely regarded as an area of extraordinary difficulty in children with Specific Language Impairment (SLI). A main argument for this view is the purported high diagnostic accuracy of morphological errors for the identification of SLI. However, findings are inconsistent across age groups and across languages. Studies show morphological difficulty to be far less pronounced in more highly inflected languages and the diagnostic accuracy of morphology in such languages is largely unknown. This study examines the morphological use of Icelandic children with and without SLI in a cross-sectional sample of children ranging from preschool age to adolescence and assesses the usefulness of morphology as a clinical marker to identify SLI. Participants were 57 monolingual Icelandic-speaking children age 4-14 years; 31 with SLI and 26 with typical language development (TD). Spontaneous language samples were coded for correct and incorrect use of grammatical morphology. The diversity of use of grammatical morphemes was documented for each group at different age and MLU levels. Individual accuracy scores were plotted against age as well as MLU and diagnostic accuracy was calculated. MLU and morphological accuracy increased with age for both children with SLI and TD, with the two groups gradually approaching each other. Morphological diversity and sequence of acquisition was similar across TD and SLI groups compared based on age or MLU. Morphological accuracy was overall high, but was somewhat lower in the SLI group, in particular at ages below 12 years and MLU levels below 6.0. However, overlap between the groups was important in all age groups, involving a greater tendency for errors in both groups at young ages and scores close to or at ceiling at older ages. Sensitivity rates as well as likelihood ratios for each morpheme were all below the range considered acceptable for clinical application, whereas better specificity rates in some age groups for some morphemes indicated that very low scores are indicative of SLI whereas high scores are uninformative. Age effects were evident in that the morphemes varied in the age at which they separate the groups most accurately. The findings of this study show that Icelandic children with SLI are somewhat more prone to making morphological errors than their TD counterparts. However, great overlap exists between the groups. The findings call into question the view that grammatical morphology is a central area of deficit in SLI. Copyright © 2016 Elsevier Inc. All rights reserved.