MulTi-FAST: A Machinability Assessment of Functionally Graded Titanium Billets Produced from Multiple Alloy Powders.

Technological developments in the area of functionally graded multi-material manufacture are poised to disrupt the aerospace industry, providing the means for step-change improvements in performance through tailored component design. However, the challenges faced during the downstream processing, i.e., machining of such functionally graded multi-materials are unclear. In this study, the challenges involved when face-turning billets consisting of multiple alloys are assessed. To achieve this, a cylindrical billet consisting of Ti-64, Ti-6242, Ti-5553 and Beta C alloys was manufactured from powder feedstock using field-assisted sintering technique (FAST) and termed MulTi-FAST billets. A detailed study of the structural integrity during machining at the diffusion bond interfaces of multiple titanium alloy bond pairings in the MulTi-FAST billet was conducted. The machining forces were measured during face-turning to investigate the impact and behaviour of different alloy pairings during a continuous machining operation. The results showed the significant differences in force machining response, surface topography and the type of surface damage was dependent on the direction the titanium alloy graded pairings were machined in. In terms of subsurface microstructural damage, regardless of the machining direction, no critical damage was found in the vicinity of the bonded alloys. The findings provide an insight into the deformation characteristics and challenges faced in the machining of functionally graded components with multiple titanium alloys.

Adding remnant magnetization and anisotropic exchange to propeller-like single-molecule magnets through chemical design.

The selective replacement of the central iron(III) ion with vanadium(III) in a tetrairon(III) propeller-shaped single-molecule magnet has allowed us to increase the ground spin state from S=5 to S=13/2. As a consequence of the pronounced anisotropy of vanadium(III), the blocking temperature for the magnetization has doubled. Moreover, a significant remnant magnetization, practically absent in the parent homometallic molecule, has been achieved owing to the suppression of zero-field tunneling of the magnetization for the half-integer molecular spin. Interestingly, the contribution of vanadium(III) to the magnetic anisotropy barrier occurs through the anisotropic exchange interaction with iron(III) spins and not through single ion anisotropy as in most single-molecule magnets.

Andreev reflection, a tool to investigate vortex dynamics and quantum turbulence in 3He-B.

Andreev reflection of quasiparticle excitations provides a sensitive and passive probe of flow in superfluid (3)He-B. It is particularly useful for studying complex flows generated by vortex rings and vortex tangles (quantum turbulence). We describe the reflection process and discuss the results of numerical simulations of Andreev reflection from vortex rings and from quantum turbulence. We present measurements of vortices generated by a vibrating grid resonator at very low temperatures. The Andreev reflection is measured using an array of vibrating wire sensors. At low grid velocities, ballistic vortex rings are produced. At higher grid velocities, the rings collide and reconnect to produce quantum turbulence. We discuss spatial correlations of the fluctuating vortex signals measured by the different sensor wires. These reveal detailed information about the formation of quantum turbulence and about the underlying vortex dynamics.

Characterization of cerebellar ataxia in chronic alcoholics using the International Cooperative Ataxia Rating Scale (ICARS).

BACKGROUND: Alcoholism is the most common cause of cerebellar dysfunction, yet estimates of the incidence of alcoholic cerebellar degeneration (ACD) vary greatly, with differences in methodologies contributing to these disparate findings. This study set out to characterize the frequency and pattern of clinical signs of ACD in an alcoholic group using the International Cooperative Ataxia Rating Scale (ICARS). METHODS: We compared the performance of 49 alcoholics and 29 control participants. The relative contributions of demographic and alcohol consumption variables to ICARS scores in the alcoholic group were also examined. RESULTS: The alcoholic group demonstrated significantly poorer performance on all of the ICARS subscales as compared with the control group. Within the alcoholic group, performance was more impaired on the speech scale than on all of the other scales, except the lower limb component of the kinetic scale, and less impaired on the oculomotor scale compared with all other scales. Years of heavy drinking and lifetime alcohol consumption correlated with total ICARS scores; however, maximum daily consumption was actually negatively correlated with ICARS scores. Of the alcohol history variables, years of heavy drinking was the best predictor of total ICARS scores, making a 19% unique contribution, followed by the period of abstinence from alcohol, which uniquely contributed 7% of the variance. There were high correlations between age and male gender and the alcohol consumption variables; however, age and gender were still found to uniquely contribute 5 and 7% respectively to the variance in total ICARS scores. CONCLUSIONS: ACD may affect up to two-thirds of chronic alcoholics. Assessing the number of years an individual has been drinking beyond a certain threshold can give a good indication of the likelihood of ACD. Age, gender, and the source of the clinical sample may significantly contribute to the prevalence of ACD and require further detailed investigation.

Compromised verbal episodic memory with intact visual and procedural memory during pregnancy.

This study investigated episodic and procedural memory performance in early and late pregnancy. Twenty-six women in the third trimester of pregnancy, 20 women in the first trimester of pregnancy, and 24 nonpregnant controls were administered a battery of verbal and visual episodic memory tasks and two procedural memory tasks. Results indicated that compared to controls, both pregnant groups had reduced scores on immediate and delayed verbal episodic memory tasks, but were unimpaired on visual and procedural memory tasks. Verbal memory differences could not be accounted for by mood state or attention; however, progesterone level accounted for a small amount of the variation. Although memory differences were minor, the perception of memory problems may have implications for everyday living for pregnant women.

Decreased sleep efficiency, increased wake after sleep onset and increased cortical arousals in late pregnancy.

BACKGROUND: Anecdotal reports of sleep disturbance during pregnancy are abundant; however, objective measurement of sleep changes has so far produced conflicting results. AIMS: To objectively measure sleep architecture and investigate subjective sleep quality in the first and third trimester of pregnancy, when compared to the nonpregnant state. METHODS: Twenty-seven women in the third trimester of pregnancy, 21 women in the first trimester of pregnancy and 24 nonpregnant control women underwent overnight polysomnography and completed questionnaires regarding sleep quality and mood. RESULTS: Women in the third trimester of pregnancy had poorer sleep efficiency, more awakenings, less stage 4 sleep, more stage 1 sleep and fewer minutes in rapid eye movement sleep when compared to the control group. Cortical arousals were seen more often during pregnancy, particularly in response to respiratory events and limb movements. Sleep during the first trimester was affected to a lesser extent, with more wake time after sleep onset and less stage 4 sleep when compared to the controls. CONCLUSIONS: Sleep during pregnancy is compromised by higher amounts of wake and cortical arousals leading to sleep fragmentation, with greater amounts of light sleep and less deep sleep. Mood state did not have an effect on sleep. Given the impact of sleep on well-being, this study increases our understanding of the characteristics of sleep during pregnancy, to help recognise when severe sleep disruption may warrant referral to a specialist for appropriate diagnosis and treatment.

A meta-analytic review of the emotional symptoms associated with mild traumatic brain injury.

Given the prevalence of mild traumatic brain injury (mTBI) and enduring subjective complaints known as postconcussion symptoms (PCS), it is important to investigate the nature and extent of these difficulties. This study used meta-analytic techniques to integrate the available information on the emotional symptoms associated with mTBI. Small effect sizes were found across all domains (depression, anxiety, coping, and psychosocial disability); however, significance depended upon the weighting method employed. The results indicate that mTBI had a small to negligible effect on emotional symptom reporting. This has implications for the etiology of PCS, the delivery of therapeutic interventions, and medico-legal disputations.

Interference effects on commonly used memory tasks.

This paper reports two studies which investigated the effect of interference on delayed recall scores of the WMS-III and other commonly used memory measures. In Study 1, participants completed the immediate and delayed components of the WMS-III, with or without the introduction of conceptually similar memory tasks between the recall trials. In Study 2, this order of administration was reversed, with the WMS-III subtests used as the interference items. The results indicated that the introduction of interference items during the delay negatively affected delayed recall performance on almost all sub-tests. In addition, equal effects of proactive and retroactive interference were demonstrated. These findings raise concerns regarding the standardization process for memory tasks and highlight the need to consider interference effects in clinical practice, and stand as a caution in the use of memory-related materials during the delay interval in memory testing.

Recovery of components of memory in post-traumatic amnesia.

PRIMARY OBJECTIVE: Post-traumatic amnesia by definition indicates significant impairment of new learning ability, however very few studies have, examined the natural history and resolution of memory and new learning during PTA. Those studies which have, tended to examine orientation separately from the memory processes required to achieve orientation. Analysis of the order of recovery of the items of the Westmead PTA scale was used to examine recovery of memory and new learning capacity. METHODS: The results of daily assessment of 34 patients with traumatic brain injury (TBI) on the Westmead PTA scale were analysed for order of recovery. RESULTS: The pattern of rank order of item recovery indicated that Date of Birth recovered consistently first. There was variability in the remaining items, however items reflecting long-term memory tended to recover second and items reflecting simple new learning followed. Recall of all three pictures reflecting complex new learning recovered last. CONCLUSION: The pattern of recovery of memory and new learning during PTA reflects a number of complex, inter-related variables including; the familiarity with the information, amount of rehearsal both before and since the accident and the number of cues available in the environment.

An evaluation of persisting cognitive effects after withdrawal from long-term benzodiazepine use.

Twenty participants with self-reported long-term benzodiazepine use (mean 108 months) who had previously withdrawn from medication (mean 42 months) were administered a battery of neuropsychological tests. Each long-term user was case matched for age, sex, and education to two control participants who reported never taking benzodiazepines (those with and those without anxiety). The results indicated that long-term benzodiazepine use may lead to impairments in the areas of verbal memory, motor control/performance, and nonverbal memory but not visuospatial skills and attention/concentration. The length of abstinence (> 6 months) indicates that these impairments persist well beyond cessation of benzodiazepine use. However, observed impairments in the area of nonverbal memory were not solely attributable to benzodiazepine use and may be influenced by the elevated anxiety levels present in both the case and the anxious control group.

Predicting competency in automated machine use in an acquired brain injury population using neuropsychological measures.

The purpose of the current study was to explore whether performance on standardised neuropsychological measures could predict functional ability with automated machines and services among people with an acquired brain injury (ABI). Participants were 45 individuals who met the criteria for mild, moderate or severe ABI and 15 control participants matched on demographic variables including age- and education. Each participant was required to complete a battery of neuropsychological tests, as well as performing three automated service delivery tasks: a transport automated ticketing machine, an automated teller machine (ATM) and an automated telephone service. The results showed consistently high relationship between the neuropsychological measures, both as single predictors and in combination, and level of competency with the automated machines. Automated machines are part of a relatively new phenomena in service delivery and offer an ecologically valid functional measure of performance that represents a true indication of functional disability.

Persistence of cognitive effects after withdrawal from long-term benzodiazepine use: a meta-analysis.

Despite the widespread prescribing of benzodiazepines, uncertainty still surrounds the potential for cognitive impairment following their long-term use. Furthermore, the degree of recovery that may take place after withdrawal or the level of residual impairment, if any, that is maintained in long-term benzodiazepine users is also unclear. The current paper employed meta-analytic techniques to address two questions: (1) Does the cognitive function of long-term benzodiazepine users improve following withdrawal? (2) Are previous long-term benzodiazepine users still impaired at follow-up compared to controls or normative data? Results of the meta-analyses indicated that long-term benzodiazepine users do show recovery of function in many areas after withdrawal. However, there remains a significant impairment in most areas of cognition in comparison to controls or normative data. The findings of this study highlight the problems associated with long-term benzodiazepine therapy and suggest that previous benzodiazepine users would be likely to experience the benefit of improved cognitive functioning after withdrawal. However, the reviewed data did not support full restitution of function, at least in the first 6 months following cessation and suggest that there may be some permanent deficits or deficits that take longer than 6 months to completely recover.

Cognitive effects of long-term benzodiazepine use: a meta-analysis.

INTRODUCTION: While benzodiazepines are the most widely used psychotropic drugs, there are relatively few studies that have examined deficits in cognitive functioning after long-term use. The literature that is available is difficult to interpret due to conflicting results as well as a variety of methodological flaws. OBJECTIVE: To systematically evaluate and integrate the available research findings to determine the effect of long-term benzodiazepine use on cognitive functioning using meta-analytical techniques. METHODS: Thirteen research studies that employed neuropsychological tests to evaluate cognitive performance after long-term use of benzodiazepine medication met inclusion criteria. The neuropsychological tests employed in these 13 studies were each categorised as measuring one of 12 cognitive domains. Separate effect sizes were calculated for each of the 12 cognitive categories. Each study was only allowed to contribute one effect size to each cognitive category by averaging together the effect sizes from the same study if more than one type of test was used to measure a particular category. This strategy resulted in equal weight being given to each study per category, regardless of the number of tests in that category. RESULTS: The overall mean number of patients who were benzodiazepine users was 33.5 (SD +/- 28.9) and the mean number of controls was 27.9 (SD +/- 19.6). The duration of benzodiazepine use ranged from 1 to 34 (mean 9.9) years. Long-term benzodiazepine users were consistently more impaired than controls across all cognitive categories examined, with effect sizes ranging in magnitude from -1.30 to -0.42. The mean weighted effect size was -0.74 (SD +/- 0.25). None of the effect sizes had 95% CIs that spanned zero and, therefore, all of these effects were significant and different to zero. CONCLUSION: Moderate-to-large weighted effect sizes were found for all cognitive domains suggesting that long-term benzodiazepine users were significantly impaired, compared with controls, in all of the areas that were assessed. However, this study has several limitations, one being that it includes a relatively small number of studies. Further studies need to be conducted; ideally, well designed, controlled studies that thoroughly investigate certain areas of cognitive functioning and present data in such a way so as to be amenable to inclusion in a meta-analysis. Incorporating the information from these studies into a larger meta-analysis would allow for a more thorough and statistically sound investigation of the effects of moderator variables. The observation that long-term benzodiazepine use leads to a generalised effect on cognition has numerous implications for the informed and responsible prescription of these drugs.