Αποτύπωση σφαλμάτων εξειλιγμένης και εξέλιξη τους κατά την διαδικασία στίλβωσης με χρήση τεχνικών αντίστροφου σχεδιασμού σε βαθμίδα τοξοτών κωνικών τροχών

Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.

Employing surfactant-assisted hydrothermal synthesis to control CuGaO2 nanoparticle formation and improved carrier selectivity of perovskite solar cells

Delafossites like CuGaO2 have appeared as promising p-type semiconductor materials for opto-electronic applications mainly due to their high optical transparency and electrical conductivity. However, existing synthetic efforts usually result in particles with large diameter limiting their performance relevant to functional electronic applications. In this article, we report a novel surfactant-assisted hydrothermal synthesis method, which allows the development of ultrafine (~5 nm) monodispersed p-type CuGaO2 nanoparticles (NPs). We show that DMSO can be used as a ligand and dispersing solvent for stabilizing the CuGaO2 NPs. The resulting dispersion is used for the fabrication of dense, compact functional CuGaO2 electronic layer with properties relevant to advanced optoelectronic applications. As a proof of concept, the surfactant-assisted hydrothermal synthesized CuGaO2 is incorporated as a hole transporting layer (HTL) in the inverted p-i-n perovskite solar cell device architecture providing improved hole carrier selectivity and power conversion efficiency compared to conventional PEDOT:PSS HTL based perovskite solar cells

Eating, chewing and the mind

The need for detailed description of eating behavior has become relevant by the limited success of simplified models in genetics and neuroscience to explain and predict eating behavior in humans. Failure of cognitive interventions, combined with the success of treatments normalising eating styles in obesity and eating disorders, demonstrates the central role of eating in dealing with these problems. In continuous recording of eating behavior and satiety over the course of a meal, women have been found to eat either at a decelerated or a constant rate. Linear eaters, unlike decelerated ones, are unable to control their food intake when the rate of eating is experimentally increased or decreased and their rating of satiety become disassociated from the actual food intake. Their responses to these experimental challenges simulate the eating patterns and the satiation ratings of anorexic and binge eating disorder patients. The development of an improved methodology for the analysis of single meals, combining video derived and intake data, allows for the analysis of the distinct behavioral elements of the meal over time. Semi-automation, high validity and reliability make this procedure ideal for comparing eating patterns among different groups of individuals. The chewing frequency, the distribution of chews within the chewing sequences and the pauses between mouthfuls remain stable across the meal both in decelerated and linear eaters. The weight of the mouthfuls decreases and the duration of the chewing sequences increases over time in the decelerated eaters, but not the linear ones, clarifying the nature of deceleration. Additionally, the default chewing frequency, quantified by the use of chewing gum, is lower in linear than in decelerated eaters, indicating that there is a baseline difference in the default chewing frequency between the two groups. It is suggested that linear eating is a behavioral risk factor for the development of disordered eating and it is hypothesized that while repeated disordered eating is the cause of eating disorders, the accompanying chewing characteristics might be the mediator of the emotional profile that characterizes patients with eating disorders

A Splicing Mutation in the Novel Mitochondrial Protein DNAJC11 Causes Motor Neuron Pathology Associated with Cristae Disorganization, and Lymphoid Abnormalities in Mice

Mitochondrial structure and function is emerging as a major contributor to neuromuscular disease, highlighting the need for the complete elucidation of the underlying molecular and pathophysiological mechanisms. Following a forward genetics approach with N-ethyl-N-nitrosourea (ENU)-mediated random mutagenesis, we identified a novel mouse model of autosomal recessive neuromuscular disease caused by a splice-site hypomorphic mutation in a novel gene of unknown function, DnaJC11. Recent findings have demonstrated that DNAJC11 protein co-immunoprecipitates with proteins of the mitochondrial contact site (MICOS) complex involved in the formation of mitochondrial cristae and cristae junctions. Homozygous mutant mice developed locomotion defects, muscle weakness, spasticity, limb tremor, leucopenia, thymic and splenic hypoplasia, general wasting and early lethality. Neuropathological analysis showed severe vacuolation of the motor neurons in the spinal cord, originating from dilatations of the endoplasmic reticulum and notably from mitochondria that had lost their proper inner membrane organization. The causal role of the identified mutation in DnaJC11 was verified in rescue experiments by overexpressing the human ortholog. The full length 63 kDa isoform of human DNAJC11 was shown to localize in the periphery of the mitochondrial outer membrane whereas putative additional isoforms displayed differential submitochondrial localization. Moreover, we showed that DNAJC11 is assembled in a high molecular weight complex, similarly to mitofilin and that downregulation of mitofilin or SAM50 affected the levels of DNAJC11 in HeLa cells. Our findings provide the first mouse mutant for a putative MICOS protein and establish a link between DNAJC11 and neuromuscular diseases

Neurodevelopment & risk factors in schizophrenia

Schizophrenia is a complex psychiatric disorder with positive, negative, and cognitive symptoms. The causes are not yet fully understood, but it is believed that together with a strong genetic foundation, a ‘second environmental hit’ may be responsible to triggering a psychotic episode. Early-onset schizophrenia (EOS) a rare and more severe form of the disorder compared to its adult-onset counterpart and it is regarded to be more genetically loaded. This being as children and adolescents are less likely to have accumulated environmental triggers that are often considered risks to develop schizophrenia. Neurotic personality and anxiety symptoms are considered candidate schizophrenia risk factors. Working memory (WM) performance, the ability to hold information “online” in the matter of a few seconds, as well as its neural correlates are severely impaired in EOS, and such impairment is considered endophenotypic to the disorder. In addition, the expression of neurophysiological indices of cognition such as the mismatch negativity (MMN) and P300 event-related potentials (ERPs) are consistently demonstrated to be reliable biomarkers for the disorder, as shown by electroencephalography. This thesis on one hand, explores the influence of neuroticism and anxiety levels in healthy participants in ERPs during the auditory roving oddball and the hollow mask illusion experiments that are continually shown to be affected in schizophrenia literature. On the other hand, it explores meta-analytically convergent structural and functional brain abnormalities in EOS literature and follows a longitudinal fMRI cohort of EOS and healthy adolescents who were scanned twice in a 4-year span, while they performed the n-back task (WM task). These experiments are aimed to reveal brain areas that may qualify as endophenotypic markers of impaired WM neurodevelopment in schizophrenia. Our results showed that anxiety and neuroticism do not fully explain their status as schizophrenia risk factors by their relationship with the schizophrenia biomarker ERPs (P50 sensory gating, MMN, P300 and P600). The meta- analysis strongly indicates that a dysfunction in the functional network that underlies salience and other executive functions related to incentive and goal-oriented processes may be central across cognitive paradigms in EOS. Longitudinally, functional connectivity and maturation impairments are prevalent in the WM functional substrate of adolescents with EOS as they undergo neurodevelopmental processes by transitioning into early adulthood

A Meta-analysis of Structural and Functional Brain Abnormalities in Early-Onset Schizophrenia

Early-onset schizophrenia (EOS) patients demonstrate brain changes that are similar to severe cases of adult-onset schizophrenia. Neuroimaging research in EOS is limited due to the rarity of the disorder. The present meta-analysis aims to consolidate MRI and functional MRI findings in EOS. Seven voxel-based morphometry (VBM) and 8 functional MRI studies met the inclusion criteria, reporting whole-brain analyses of EOS vs healthy controls. Activation likelihood estimation (ALE) was conducted to identify aberrant anatomical or functional clusters across the included studies. Separate ALE analyses were performed, first for all task-dependent studies (Cognition ALE) and then only for working memory ones (WM ALE). The VBM ALE revealed no significant clusters for gray matter volume reductions in EOS. Significant hypoactivations peaking in the right anterior cingulate cortex (rACC) and the right temporoparietal junction (rTPJ) were detected in the Cognition ALE. In the WM ALE, consistent hypoactivations were found in the left precuneus (lPreC), the right inferior parietal lobule (rIPL) and the rTPJ. These hypoactivated areas show strong associations with language, memory, attention, spatial, and social cognition. The functional co-activated networks of each suprathreshold ALE cluster, identified using the BrainMap database, revealed a core co-activation network with similar topography to the salience network. Our results add support to posterior parietal, ACC and rTPJ dysfunction in EOS, areas implicated in the cognitive impairments characterizing EOS. The salience network lies at the core of these cognitive processes, co-activating with the hypoactivating regions, and thus highlighting the importance of salience dysfunction in EOS

Systematic framework for performance evaluation of exoskeleton actuators

AbstractWearable devices, such as exoskeletons, are becoming increasingly common and are being used mainly for improving motility and daily life autonomy, rehabilitation purposes, and as industrial aids. There are many variables that must be optimized to create an efficient, smoothly operating device. The selection of a suitable actuator is one of these variables, and the actuators are usually sized after studying the kinematic and dynamic characteristics of the target task, combining information from motion tracking, inverse dynamics, and force plates. While this may be a good method for approximate sizing of actuators, a more detailed approach is necessary to fully understand actuator performance, control algorithms or sensing strategies, and their impact on weight, dynamic performance, energy consumption, complexity, and cost. This work describes a learning-based evaluation method to provide this more detailed analysis of an actuation system for ourXoTrunkexoskeleton. The study includes: (a) a real-world experimental setup to gather kinematics and dynamics data; (b) simulation of the actuation system focusing on motor performance and control strategy; (c) experimental validation of the simulation; and (d) testing in real scenarios. This study creates a systematic framework to analyze actuator performance and control algorithms to improve operation in the real scenario by replicating the kinematics and dynamics of the human–robot interaction. Implementation of this approach shows substantial improvement in the task-related performance when applied on a back-support exoskeleton during a walking task

Functional neurodevelopment of working memory in early-onset schizophrenia: A longitudinal FMRI study

Schizophrenia, a debilitating disorder with typical manifestation of clinical symptoms in early adulthood, is characterized by cognitive impairments in executive processes such as in working memory (WM). However, there is a rare case of individuals with early-onset schizophrenia (EOS) starting before their 18th birthday, while WM and its neural substrates are still undergoing maturation. Using the WM n-back task with functional magnetic resonance imaging, we assessed the functional neurodevelopment of WM in adolescents with EOS and age- and gender-matched typically developing controls. Participants underwent neuroimaging in the same scanner twice, once at age 17 and at 21 (mean interscan interval = 4.3 years). General linear model analysis was performed to explore WM neurodevelopmental changes within and between groups. Psychopathological scores were entered in multiple regressions to detect brain regions whose longitudinal functional change was predicted by baseline symptoms in EOS. WM neurodevelopment was characterized by widespread functional reductions in frontotemporal and cingulate brain areas in patients and controls. No between-group differences were found in the trajectory of WM change. Baseline symptom scores predicted functional neurodevelopmental changes in frontal, cingulate, parietal, occipital, and cerebellar areas. The adolescent brain undergoes developmental processes such as synaptic pruning, which may underlie the refinement WM of network. Prefrontal and parietooccipital activity reduction is affected by clinical presentation of symptoms. Using longitudinal neuroimaging methods in a rare diagnostic sample of patients with EOS may help the advancement of neurodevelopmental biomarkers intended as pharmacological targets to tackle WM impairment