Dual task performance of working memory and postural control in major depressive disorder

Objective: Previous studies with patients diagnosed with Major Depressive Disorder (MDD) revealed deficits in working memory and executive functions. In the present study we investigated whether patients with MDD have the ability to allocate cognitive resources in dual task performance of a highly challenging cognitive task (working memory) and a task that is seemingly automatic in nature (postural control). Method: Fifteen young (18–35 years old) patients with MDD and 24 healthy age-matched controls performed a working memory task and two postural control tasks (standing on a stable or on a moving platform) both separately (single task) and concurrently (dual task). Results: Postural stability under single task conditions was similar in the two groups, and in line with earlier studies, MDD patients recalled fewer working memory items than controls. To equate working memory challenges for patients and controls, task difficulty (number of items presented) in dual task was individually adjusted such that accuracy of working memory performance was similar for the two groups under single task conditions. Patients showed greater postural instability in dual task performance on the stable platform, and more importantly when posture task difficulty increased (moving platform) they showed deficits in both working memory accuracy and postural stability compared with healthy controls. Conclusions: We interpret our results as evidence for executive control deficits in MDD patients that affect their task coordination. In multitasking, these deficits affect not only cognitive but also sensorimotor task performance.

A design model: the Autism Spectrum Disorder Classroom Design Kit

Architects and designers have a responsibility to provide an inclusive built environment. However for those with a diagnosis of Autism Spectrum Disorder (ASD), the built environment can be a frightening and confusing place, difficult to negotiate and tolerate. The challenge of integrating more fully into society is denied by an alienating built environment. For ASD pupils in a poorly designed school, their environment can distance them from learning. Instead, if more at ease in their surroundings, in an ASD-friendly environment, the ASD pupil stands a greater chance of doing better.

However a difficulty exists in that most architects are not knowledgeable in designing for those with ASD. Any available design guidelines for architects tend, because of the inherent difficulties associated with a spectrum, to be general in their information. Therefore, if wanting to provide an ASD-friendly learning environment, there is a need to ensure that teachers, as the experts, can most clearly and effectively impart their knowledge and requirements to architects.

This paper sets out the challenges and difficulties inherent in the design process when designing for ASD. It then sets out an alternative strategy to the usual method of drawing-centric dialogue between teacher and architect by using models instead as a basis for a more common language. An ASD Classroom Design Kit was designed and developed by Queen’s University of Belfast Architecture students. It was then used by ASD teaching staff from the Southern Education and Library Board in Northern Ireland as a case study to trial its effectiveness. The paper outlines how the study was carried out before concluding with reflections by both teaching staff and architect on using the ASD Classroom Design Kit.

It is hoped that this paper will firstly highlight the need for better dialogue between expert and architect when considering ASD and the Built Environment and secondly, that it may encourage others to consider using models to convey their ideas and knowledge when designing, not just for ASD, but for other Special Educational Needs and disabilities.

A pseudo-transient solution strategy for the analysis of delamination by means of interface elements

Recent efforts in the finite element modelling of delamination have concentrated on the development of cohesive interface elements. These are characterised by a bilinear constitutive law, where there is an initial high positive stiffness until a threshold stress level is reached, followed by a negative tangent stiffness representing softening (or damage evolution). Complete decohesion occurs when the amount of work done per unit area of crack surface is equal to a critical strain energy release rate. It is difficult to achieve a stable, oscillation-free solution beyond the onset of damage, using standard implicit quasi-static methods, unless a very refined mesh is used. In the present paper, a new solution strategy is proposed based on a pseudo-transient formulation and demonstrated through the modelling of a double cantilever beam undergoing Mode I delamination. A detailed analysis into the sensitivity of the user-defined parameters is also presented. Comparisons with other published solutions using a quasi-static formulation show that the pseudo-transient formulation gives improved accuracy and oscillation-free results with coarser meshes

An investigation of Mode I fracture toughness using aligned carbon nanotube forests at the crack interface

This paper presents a novel approach for introducing aligned carbon nanotubes (CNTs) at the crack interface of pre-impregnated (prepreg) carbon fibre composite plies, creating a hierarchical (three-phase) composite structure. The aim of this approach is to improve the interlaminar fracture toughness. The developed method for transplanting the aligned CNTs from the silicon wafer onto the pre-preg material is described. Scanning electron microscopy (SEM) was used to analyse the effects of the transplantation method. Double Cantilever Beam (DCB) specimens were prepared, according to ASTM standard D5528- 01R07E03 [1] and aligned multi-walled carbon nanotubes (MWCNTs) were introduced at the crack-tip. Mode I fracture tests for pristine (control) specimens and CNT-enhanced specimens were conducted and an average increase in the critical strain energy release rate (GIc) of approximately 50 % was achieved.

Quasiparticle calculations of the electronic properties of ZrO2 and HfO2 polymorphs and their interface with Si

Quasiparticle calculations are performed to investigate the electronic band structures of various polymorphs of Hf and Zr oxides. The corrections with respect to density-functional-theory results are found to depend only weakly on the crystal structure. Based on these bulk calculations as well as those for bulk Si, the effect of quasiparticle corrections is also investigated for the band offsets at the interface between these oxides and Si assuming that the lineup of the potential at the interface is reproduced correctly within density-functional theory. On the one hand, the valence-band offsets are practically unchanged with a correction of a few tenths of electron volts. On the other hand, conduction-band offsets are raised by 1.3-1.5 eV. When applied to existing calculations for the offsets at the density-functional-theory level, our quasiparticle corrections provide results in good agreement with the experiment.

Developmental coordination disorder in extremely low birth weight children at nine years

Developmental coordination disorder (DCD) is defined as an impairment in the development of motor coordination that interferes with academic achievement or activities of daily living (DSM-IV). DCD has been reported to affect 5% to 9% of children in the normal population. This study describes the prevalence of DCD in a cohort of extremely low birth weight children (ELBW, <or = l800 g) at 8.9 years of age, from which were excluded children with major impairments. Seventy-three children were included in the study group, along with 18 term-born, socially matched controls. Of the 73 ELBW children, 37 (51%) were classified as having DCD. ELBW children with DCD also had significantly lower Performance IQ (PIQ) scores and were more likely (43%) to have a learning difficulty in arithmetic than ELBW children who did not have DCD. This study found that DCD is a common problem in school-aged ELBW children.

Autobiographical memory specificity, depression, and trauma in bipolar disorder

Objectives. In a bipolar disorder (BD) sample, the present study investigated: (i) the prevalence of trauma; (ii) the specificity of autobiographical memory (AM); (iii) the influence of childhood trauma on AM specificity, current inter-episode depressive mood, and BD severity; (iv) if AM specificity moderates the influence of childhood trauma on current inter-episode depressive mood and BD severity.

Methods. Fifty-two participants were recruited from a geographically well-defined mental health service in Northern Ireland. The AM test, self-report measures of lifetime experience of trauma, childhood trauma, and depression were administered. Severity of BD was estimated utilizing a systematic tool for reviewing all available clinical data of participants.

Results. A high prevalence of trauma was found. A total of 94.2% (49/52) of participants reported experiencing a traumatic event in either childhood or adulthood. AM specificity was significantly lower than previous reports of such in major depression. However, whilst childhood trauma predicted current inter-episode depressive mood, childhood trauma was not predictive of BD severity or AM specificity. Moreover, the association between childhood trauma and depressed mood was not moderated by AM specificity.

Conclusions. The findings of this study suggest a relationship between early psychosocial adversity and current inter-episode depressive mood in BD. In addition, levels of overgeneral AM are similar to that reported for depression, but are unrelated to childhood trauma, current inter-episode depressive mood, or BD severity. Clinical implications include the importance of routine assessment of trauma in BD and the need for adjunctive evidenced-based psychological therapies.

Enquiring about traumatic experiences in bipolar disorder: A case note and self- report comparison

Objectives: This study examined: (i) the prevalence of lifetime trauma, childhood trauma and trauma related to civil unrest in a Bipolar Disorder sample, and (ii) the agreement between rates of disclosure of trauma in case notes and self-report questionnaires.

Methods: The case notes of sixty participants, recruited from a geographically well-defined mental health service in Northern Ireland, were examined for reports of experiences of lifetime, childhood and traumatic events related to civil conflict. The participants also completed self-report measures of trauma.

Results: Considerable differences were found between the prevalence of trauma as measured by self-report questionnaires and case notes reports. The prevalence of lifetime trauma as measured by the Trauma History Questionnaire was 61.7% (compared to case notes prevalence of 33.3%). The prevalence of moderate and severe levels of childhood trauma as measured by the Childhood Trauma Questionnaire was 65% (case notes 21.7%). Rates of trauma related to civil unrest were 35% (case notes 3.3%). Poor levels of agreement were found between all self-report trauma measures and case notes reports. Agreement on two categories of trauma (childhood emotional neglect and childhood physical neglect) reached statistical significance but kappa scores suggest this agreement was poor (kappa = .14. p<.05; kappa = .127, p<.05). © 2011 Elsevier B.V. All rights reserved.

Conclusions: It is probable that the increased rate of trauma disclosed in the self-report questionnaire arises because clinicians during initial assessment and subsequent treatment do not consistently enquire about trauma. The need for staff training is discussed. (C) 2011 Elsevier B.V. All rights reserved.

Asprich Peptides Are Occluded in Calcite and Permanently Disorder Biomineral Crystals

Macromolecules are a minority but important component of the minerals formed by living organisms, or biominerals. The role these macromolecules play at the early stages of biomineral formation, as well as their long-term and long-range effects on the mature biomineral, is poorly understood. A 42-amino acid peptide, asp2, was derived from the Asprich family of proteins. In this study we present X-ray absorption near-edge structure spectroscopy and X-ray photoelectron emission microscopy data from the asp2 peptide, the calcite (CaCO3) crystals, and the peptide + crystal composites. The results clearly show that asp2 is occluded in fully formed biomineral crystals and slightly but permanently disorders the crystal structure at short- and long-range distances.

On thin ice: surface order and disorder during pre-melting

The effect of temperature on the structure of the ice Ih (0001) surface is considered through a series of molecular dynamics simulations on an ice slab. At relatively low temperatures (200K) a small fraction of surface self-interstitials (i.e. admolecules) appear that are formed exclusively from molecules leaving the outermost bilayer. At higher temperatures (ca. 250 K), vacancies start to appear in the inner part of the outermost bilayer exposing the underlying bilayer and providing sites with a high concentration of the dangling hydrogen bonds. Around 250-260 K aggregates of molecules formed on top of the outermost bilayer from self-interstitials become more mobile and have diffusivities approaching that of liquid water. At similar to 270-280 K the inner bilayer of one surface noticeably destructures and it appears that at above 285 K both surfaces are melting. The observed disparity in the onset of melting between the two sides of the slab is rationalised by considering the relationship between surface energy and the spatial distribution of protons at the surface; thermodynamic stability is conferred on the surface by maximising separations between dangling protons at the crystal exterior. Local hotspots associated with a high dangling proton density are suggested to be susceptible to pre-melting and may be more efficient at trapping species at the external surface than regions with low concentrations of protons thus potentially helping ice particles to catalyse reactions. A preliminary conclusion of this work is that only about 10-20 K below the melting temperature of the particular water potential employed is major disruption of the crystalline lattice noted which could be interpreted as being "liquid", the thickness of this film being about a nanometre.