Analysis of Multi-Directional Recycled Jute Fiber Composite Behavior Using Experimental, Numerical, and Analytical Methods

Composite materials are increasing in popularity as a material of choice in many engineering applications. Major industries using composites include automotive, construction, and sports equipment. Most of the knowledge, research, and technology that will help decrease the cost of composite materials have been aimed at developing synthetic fibers as the reinforcing constituent. This thesis characterizes jute fibers obtained as a byproduct from the coffee industry to determine if they can be viable in composite manufacturing. Experimental analysis, finite element analysis, and analytical modeling are used to characterize jute fiber based composites. Experimental analysis consists of jute fiber bundle tensile testing as well as tensile testing of multiple laminates. Finite element and analytical models were developed to simulate different composite characteristics and their influence on jute composites. Finite element models investigated the influences of fiber undulation, fiber damage, and matrix porosity. Results show that certain manufacturing precautions should be taken to minimize imperfections which have negative influences on the composite. Fiber damage has the largest influence when introduced near the top of the fiber wave and can cause normal stresses to increase 56%. Fiber undulation and matrix porosity also have noticeable influences on the composite

On the Extraction and Analysis of Graphs From Resting-State fMRI to Support a Correct and Robust Diagnostic Tool for Alzheimer's Disease

The diagnosis of Alzheimer's disease (AD), especially in the early stage, is still not very reliable and the development of new diagnosis tools is desirable. A diagnosis based on functional magnetic resonance imaging (fMRI) is a suitable candidate, since fMRI is non-invasive, readily available, and indirectly measures synaptic dysfunction, which can be observed even at the earliest stages of AD. However, the results of previous attempts to analyze graph properties of resting state fMRI data are contradictory, presumably caused by methodological differences in graph construction. This comprises two steps: clustering the voxels of the functional image to define the nodes of the graph, and calculating the graph's edge weights based on a functional connectivity measure of the average cluster activities. A variety of methods are available for each step, but the robustness of results to method choice, and the suitability of the methods to support a diagnostic tool, are largely unknown. To address this issue, we employ a range of commonly and rarely used clustering and edge definition methods and analyze their graph theoretic measures (graph weight, shortest path length, clustering coefficient, and weighted degree distribution and modularity) on a small data set of 26 healthy controls, 16 subjects with mild cognitive impairment (MCI) and 14 with Alzheimer's disease. We examine the results with respect to statistical significance of the mean difference in graph properties, the sensitivity of the results to model and parameter choices, and relative diagnostic power based on both a statistical model and support vector machines. We find that different combinations of graph construction techniques yield contradicting, but statistically significant, relations of graph properties between health conditions, explaining the discrepancy across previous studies, but casting doubt on such analyses as a method to gain insight into disease effects. The production of significant differences in mean graph properties turns out not to be a good predictor of future diagnostic capacity. Highest predictive power, expressed by largest negative surprise values, are achieved for both atlas-driven and data-driven clustering (Ward clustering), as long as graphs are small and clusters large, in combination with edge definitions based on correlations and mutual information transfer

25th annual computational neuroscience meeting: CNS-2016

The same neuron may play different functional roles in the neural circuits to which it belongs. For example, neurons in the Tritonia pedal ganglia may participate in variable phases of the swim motor rhythms [1]. While such neuronal functional variability is likely to play a major role the delivery of the functionality of neural systems, it is difficult to study it in most nervous systems. We work on the pyloric rhythm network of the crustacean stomatogastric ganglion (STG) [2]. Typically network models of the STG treat neurons of the same functional type as a single model neuron (e.g. PD neurons), assuming the same conductance parameters for these neurons and implying their synchronous firing [3, 4]. However, simultaneous recording of PD neurons shows differences between the timings of spikes of these neurons. This may indicate functional variability of these neurons. Here we modelled separately the two PD neurons of the STG in a multi-neuron model of the pyloric network. Our neuron models comply with known correlations between conductance parameters of ionic currents. Our results reproduce the experimental finding of increasing spike time distance between spikes originating from the two model PD neurons during their synchronised burst phase. The PD neuron with the larger calcium conductance generates its spikes before the other PD neuron. Larger potassium conductance values in the follower neuron imply longer delays between spikes, see Fig. 17.Neuromodulators change the conductance parameters of neurons and maintain the ratios of these parameters [5]. Our results show that such changes may shift the individual contribution of two PD neurons to the PD-phase of the pyloric rhythm altering their functionality within this rhythm. Our work paves the way towards an accessible experimental and computational framework for the analysis of the mechanisms and impact of functional variability of neurons within the neural circuits to which they belong

The Effects of Four Weeks of Intranasal Oxytocin on Social Responsiveness and Repetitive and Restricted Behaviors in Autism Spectrum Disorders: A Randomized Controlled Trial

The effects of four weeks of intranasal oxytocin on social responsiveness and repetitive and restricted behaviors in autism spectrum disorders: A randomized controlled trial. S. Bernaerts, C. Dillen, J. Steyaert, and K. Alaerts Background: Autism spectrum disorders (ASDs) are characterized by impairments in social communication and interaction and repetitive and restricted behaviors. To date, no pharmacological treatment exists targeting the core symptoms of ASD, yet the past years, the pharmacological use of a neuropeptide, called oxytocin (OT), has gained increasing interest from the research community to explore its potential for elevating the core social deficits in ASD. OT is known to play a pivotal role in a variety of complex social behaviors by promoting a prosocial attitude and interpersonal bonding. Previous studies showed that exogenously administered OT can affect trust and feelings of attachment insecurity, reduce repetitive and restricted behaviors and increase social cognition. Objectives: A double-blind randomized placebo-controlled trial with thirty-four young adult men with ASD (17 OT/ 17 Placebo (PL)) was conducted to assess behavioral effects of OT therapy (i) at baseline; (ii) after four weeks of daily nasal spray administration; and (iii) four weeks post-treatment to assess potential retention effects. Methods: Doses of 24 IU oxytocin (Syntocinon®, Sigma-tau) or placebo nasal spray (PL) (saline natrium-chloride solution) (3 puffs in each nostril) were administered daily for four weeks. Primary outcome measures to assess treatment effects included the Social Responsiveness Scale (SRS) and the Repetitive Behavior Scale – Revised (RBS-R). Secondary outcome measures included assessments of changes in attachment (State Adult Attachment Scale (SAAM); Inventory of Parent and Peer Attachment (IPPA)); assessments of changes in mood state (Profile of Mood States questionnaire (POMS)); and assessments of changes is reports of quality of life (World Health Organization Quality of Life questionnaire (WHOQOL)). All participants were characterized using IQ and ADOS-scales. Thirty-four male individuals with ASD are currently enrolled in the study and recruitment is still ongoing. Results: After four weeks of OT nasal spray administration, self-reports on repetitive and restricted behaviors (RBS-R) were shown to be tentatively reduced in the OT group, not in the PL group (F(1, 31)=3.83, p=0.06) and of note, the effect of OT persisted until one month after the treatment (retention: F(1, 31)=4.02, p=0.05). Immediately after the four weeks of treatment, we found no significant effects of OT on social functioning as assessed using self- and informant-based reports of the SRS. Interestingly however, at the retention session, a significant effect was revealed for the informant-based SRS (F(1, 22)=4.90, p=0.04), indicating that clear improvements in social responsiveness emerged one month after cessation of the actual treatment (specifically for reports of social motivation (F(1, 22)=4.71, p=0.04) and social communication (F(1, 22)=7.39, p=0.01)). For the secondary outcome measures, only tentative effects were revealed, indicating improvements in self-reports of attachment immediately after the four-week treatment (F(1, 32)=3.32, p=0.08) (IPPA) and improvements in the experience of social relationships at the retention session one-month post-trial (F(1, 31)=3.07, p=0.09) (WHOQOL). Conclusions: The observed improvements after four weeks of daily treatment with intranasal OT in our primary outcome measures (assessing social responsiveness and repetitive and restricted behaviors) indicate that OT can induce long-term behavioral changes in individuals with ASD that outlast the time of intervention.status: accepte

One-year retention effects of multiple-dose oxytocin treatment on repetitive behaviors, social responsiveness and attachment: A randomized, placebo-controlled trial.

Poster presentation at INSAR 2018status: publishe

One-year retention effects of multiple-dose oxytocin treatment on repetitive behaviors, social responsiveness and attachment: A randomized, placebo-controlled trial.

Poster presentation at the "oxytocin workshop" in Ericestatus: publishe

Visual processing in adolescents with autism spectrum disorders: Evidence from embedded figures and configural superiority tests

The embedded figures test has often been used to reveal weak central coherence in individuals with autism spectrum disorder (ASD). Here, we administered a more standardized automated version of the embedded figures test in combination with the configural superiority task, to investigate the effect of contextual modulation on local feature detection in 23 adolescents with ASD and 26 matched typically developing controls. On both tasks both groups performed largely similarly in terms of accuracy and reaction time, and both displayed the contextual modulation effect. This indicates that individuals with ASD are equally sensitive compared to typically developing individuals to the contextual effects of the task and that there is no evidence for a local processing bias in adolescents with ASD.status: publishe

Influence of oxytocin on emotion recognition: a randomized placebo-controlled trial

status: publishe

Long-term effects of oxytocin on fronto-amygdala connectivity in autism: A randomized placebo-controlled trial

Autism spectrum disorders (ASD) are characterized by impairments in social interaction and repetitive and restricted behaviors. To date, no pharmacological treatment exists targeting the core symptoms of ASD, yet the pharmacological use of the neuropeptide oxytocin (OT) has gained interest from the research community to explore its potential for elevating social deficits in ASD. We aimed to examine neural and behavioral effects of single- and multiple-dose OT treatment and the possibility of retention effects one month post-treatment using a double-blind, randomized, placebo-controlled, between-subject clinical trial including thirty-eight adult men with ASD. A key question was to determine whether similar neural effects are observed after single- versus multiple-dose treatment; whether the neural effects are paralleled by behavioral improvements on core ASD symptoms and specifically, whether the observed effects can outlast the period of actual administration. Doses of 24 IU oxytocin (Syntocinon®, Sigma-tau) or placebo nasal spray (saline natrium-chloride solution) were administered daily for four weeks. Resting-state fMRI neuroimaging was adopted to evaluate ‘intrinsic’ OT-induced changes in functional connectivity of amygdala-prefrontal circuits at rest (medial prefrontal cortex and orbitofrontal cortex). Behavioral effects of OT treatment were primarily assessed on two core ASD symptoms via self-report questionnaires: restricted and repetitive behavior and social responsiveness, and secondarily, on self-reports of state attachment, trait attachment, and quality of life. Data showed that four-week OT-treatment (24 IU/day) reduced functional connectivity of the amygdala with prefrontal regions in the orbitofrontal cortex until one month post-treatment. Neural changes in amygdala-prefrontal coupling were shown to be paralleled by behavioral improvements in repetitive behavior, attachment avoidance and social motivation. These findings provide further insights into the biological mechanism by which oxytocin exerts its prosocial effects and the observation that the neural and behavioral effects outlasted the period of actual administration further supports the therapeutic potential of oxytocin interventions for ASD.status: accepte

Integrated Signal Amplification on a Fiber Optic SPR Sensor Using Duplexed Aptamers

Throughout the past decades, fiber optic surface plasmon resonance (FO-SPR)-based biosensors have proven to be powerful tools for both the characterization of biomolecular interactions and target detection. However, as FO-SPR signals are generally related to the mass that binds to the sensor surface, multistep processes and external reagents are often required to obtain significant signals for low molecular weight targets. This increases the time, cost, and complexity of the respective bioassays and hinders continuous measurements. To overcome these requirements, in this work, cis-duplexed aptamers (DAs) were implemented on FO-SPR sensors, which underwent a conformational change upon target binding. This induced a spatial redistribution of gold nanoparticles (AuNPs) upon specific target binding and resulted in an amplified and concentration-dependent signal. Importantly, the AuNPs were covalently conjugated to the sensor, so the principle does not rely on multistep processes or external reagents. To implement this concept, first, the thickness of the gold fiber coating was adapted to match the resonance conditions of the surface plasmons present on the FO-SPR sensors with those on the AuNPs. As a result, the signal obtained due to the spatial redistribution of the AuNPs was amplified by a factor of 3 compared to the most commonly used thickness. Subsequently, the cis-DAs were successfully implemented on the FO-SPR sensors, and it was demonstrated that the DA-based FO-SPR sensors could specifically and quantitatively detect an ssDNA target with a detection limit of 230 nM. Furthermore, the redistribution of the AuNPs was proven to be reversible, which is an important prerequisite for continuous measurements. Altogether, the established DA-based FO-SPR bioassay holds much promise for the detection of low molecular weight targets in the future and opens up possibilities for FO-SPR-based continuous biosensing