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BACKGROUND: Heterogeneity in the phenotypic presentation of autism spectrum disorder (ASD) is apparent in the profile and the severity of sensory features. Here, we applied factor mixture modelling (FMM) to test a multidimensional factor model of sensory processing in ASD. We aimed to identify homogeneous sensory subgroups in ASD that differ intrinsically in their severity along continuous factor scores. We also investigated sensory subgroups in relation to clinical variables: sex, age, IQ, social-communication symptoms, restricted and repetitive behaviours, adaptive functioning and symptoms of anxiety and attention-deficit/hyperactivity disorder. METHODS: Three hundred thirty-two children and adults with ASD between the ages of 6 and 30 years with IQs varying between 40 and 148 were included. First, three different confirmatory factor models were fit to the 38 items of the Short Sensory Profile (SSP). Then, latent class models (with two-to-six subgroups) were evaluated. The best performing factor model, the 7-factor structure, was subsequently used in two FMMs that varied in the number of subgroups: a two-subgroup, seven-factor model and a three-subgroup and seven-factor model. RESULTS: The 'three-subgroup/seven-factor' FMM was superior to all other models based on different fit criteria. Identified subgroups differed in sensory severity from severe, moderate to low. Accounting for the potential confounding effects of age and IQ, participants in these sensory subgroups had different levels of social-communicative symptoms, restricted and repetitive behaviours, adaptive functioning skills and symptoms of inattention and anxiety. LIMITATIONS: Results were derived using a single parent-report measure of sensory features, the SSP, which limits the generalisability of findings. CONCLUSION: Sensory features can be best described by three homogeneous sensory subgroups that differ in sensory severity gradients along seven continuous factor scores. Identified sensory subgro

Contains fulltext : 177208.pdf (publisher's version ) (Open Access), BACKGROUND: The tremendous clinical and aetiological diversity among individuals with autism spectrum disorder (ASD) has been a major obstacle to the development of new treatments, as many may only be effective in particular subgroups. Precision medicine approaches aim to overcome this challenge by combining pathophysiologically based treatments with stratification biomarkers that predict which treatment may be most beneficial for particular individuals. However, so far, we have no single validated stratification biomarker for ASD. This may be due to the fact that most research studies primarily have focused on the identification of mean case-control differences, rather than within-group variability, and included small samples that were underpowered for stratification approaches. The EU-AIMS Longitudinal European Autism Project (LEAP) is to date the largest multi-centre, multi-disciplinary observational study worldwide that aims to identify and validate stratification biomarkers for ASD. METHODS: LEAP includes 437 children and adults with ASD and 300 individuals with typical development or mild intellectual disability. Using an accelerated longitudinal design, each participant is comprehensively characterised in terms of clinical symptoms, comorbidities, functional outcomes, neurocognitive profile, brain structure and function, biochemical markers and genomics. In addition, 51 twin-pairs (of which 36 had one sibling with ASD) are included to identify genetic and environmental factors in phenotypic variability. RESULTS: Here, we describe the demographic characteristics of the cohort, planned analytic stratification approaches, criteria and steps to validate candidate stratification markers, pre-registration procedures to increase transparency, standardisation and data robustness across all analyses, and share some 'lessons learnt'. A clinical characterisation of the cohort is given in the companion paper (Charman et al., accepted). CONCLUSION: We expect that LEAP wil

Anewmethodologyhasbeendesignedtoidentifyandrankthesignificantenvironmentalaspectsinseaports.Themainobjective oftheStrategicOverviewofSignificantEnvironmentalAspects(SOSEA)istohelpportmanagerstoidentifysignificantenviron- mentalaspectsandtoreinforcetheawarenessabouttheminordertoprioritiseworkinenvironmentalmanagement.Developedin closecollaborationwithportenvironmentalmanagersandtestedinasetofports,itisauser-friendlytoolthatcanbeappliedin approximatelyhalfaworkingday.ItisbasedonISO14001vocabularyandrequirementsanditcanbeconsideredasthebaseforthe implementationofanyEnvironmentalManagementSystemforportcommunities., Postprint (published version)

The report describes an investigation of high-amplitude axial-mode solid rocket combustion instability which arises in the form of an oscillating shock wave in the combustion chamber. Experimental studies have provided an evaluation of the influence of compositional factors, oxidizer type, and deflagration characteristics on the incidence of axial instability. The stability characteristics of a wide range of ammonium perchlorate and potassium perchlorate propellants were determined in motors ranging from 15 to 82 in. in length, using an explosive pulse to initiate a traveling shock wave. Differential thermal analysis of these propellants, and experiments incorporating fiber-optic devices with high-speed photography, indicated that surface-coupled heat release is a key factor underlying the different stability behavior observed with various propellants. A theoretical combustion model was proposed and a mathematical analysis was developed that predicts the response of a burning propellant to the pressure pulse imposed by a traveling shock wave as it passes over the propellant surface. Also considered theoretically was the interaction mechanism through which this burning rate response supports the shock wave. The resulting theory predicts the limits of the stable operating regime for individual propellants in terms of thermochemical parameters and the degree of surface-coupled heat release associated with the propellant type. The theory provides a consistent explanation of all stability characteristics observed experimentally during this program and established guidelines for avoiding axial instability.

The report covers the research progress on combustion instability characteristics of solid propellants accomplished under Contract AF 49(638)- 1665, during the period 1 April through 30 June 1967. During this quarter the analytical model of transient solid propellant combustion has been modified to account for a decrease in gas-phase heat release whenever there is an increase in surface-coupled heat release, and vice versa. The computer analysis has been changed to reflect this modification. Correlation of the numerically predicted behavior with the experimental results obtained previously from traveling wave studies will allow the determination of those factors that are most influential in determining the burning rate response to sudden pressure changes. Experimental studies of the detailed structure of the flame zone, using fiber optics in conjunction with high-speed photography, have shown that both ammonium perchlorate crystals and aluminum particles may ignite at or near the surface, providing further support for the concept of surface-coupled heat release., See also AD638629.

The experiments which were performed included adiabatic self-heating (ASH) measurements, differential thermal analysis (DTA) measurements, burning rate measurements as a function of pressure, temperature profile measurements in the combustion zone, and agent yield measurements utilizing a total recovery technique. The ASH experiments defined the activation energy of a typical pyrotechnic and of binary mixtures of its ingredients and showed that a burning- rate derived activation energy is necessarily unreliable because of its dependence on the physical process of heat transfer. The DTA measurements defined the endotherms and exotherms to be expected as a function of temperature. Burning rate studies indicated that pyrotechnics have a burning rate law which resembles that of solid rockets. Agent yield measurements demonstrated that large layer pyrotechnics were more effective than small ones.

An investigation was conducted to determine the magnitude of viscous attenuation of the shock front in smooth-walled tubes with a length-to-diameter (L/D) ratio of 600. The tests were carried out in a hydrogen driven shock tube of 0.485-inch inside diameter, with air and sulfur hexafluoride as the driven gases. The pressure in the driven section was held at 1 atmosphere for the tests ranging up to a Mach number of 8.9. It was reduced below 1 atmosphere at higher mach numbers in order to avoid heating. The incident shock produced a square pressure pulse. The initial shock Mach numbers were varied from about 3.5 to 15.7. The corresponding initial shock overpressure ratios varied from about 15 to 250. (Author), Report on Project Sanguine.

The formulation of an analytical model has been initiated, to clarify the gasdynamical mechanism by which the combustion mechanism, responding to pressure pulses induced by traveling shock waves in the chamber, interacts with the shock waves to produce combustion instability. The approach taken in this analysis is similar to that used to study the behavior of shock waves in shock tubes; it differs in that it employs a modified surface boundary condition that accounts for the mass added by the combustion process. The nonlinear equations that describe the combustion model were programmed for numerical solution. The program will be used to predict the burning rate response of the combustion mechanism to steep-fronted pressure waves; this calculation will provide the proper boundary conditions for the gasdynamical studies. (Author), See also AD-657 762.

Turbulent motion in a thick (5-inch) boundary layer with zero longitudinal pressure gradient which is produced by natural transition on a smooth surface was studied. Measurements were made of the space-time correlation between the fluctuating wall pressure and the fluctuating velocities in the layer, and between the fluctuating wall pressure and the time derivative of the fluctuating velocity normal to the wall. At any height in the boundary layer, the velocity disturbance which was correlated with the wall pressure disturbances was convected at the local mean speed. The correlation of the wall pressure with the longitudinal velocity was opposite in sign to the correlation of the wall pressure with the velocity normal to the wall. This implied that the part of the velocity field which is correlated with the wall pressure also produces turbulent shear. (Author), This Report is one in the Series of papers presented at the AGARD Specialists Meeting on 'The Mechanism of Noise Generation in Turbulent Flow, held from 1-5 Apr 1963, at the Training Center for Experimental Aerodynamics, Rhode-SaintGenese, Belgium.