6,005 research outputs found
Experiences following cataract surgery - patient perspectives
PURPOSE: Most patients report being highly satisfied with the outcome of cataract surgery but there are variable reports regarding the impact of cataract surgery on some real-world activities, such as fall rates. We hypothesised that adaptations to changed refractive correction and visual function may cause difficulties in undertaking everyday activities for some patients and used a series of focus groups to explore this issue. METHOD: Qualitative methods were used to explore patients' experiences of their vision following cataract surgery, including adaptation to vision changes and their post-surgical spectacle prescription. Twenty-six participants took part in five focus groups (Mean age = 68.2 ± 11.4 years), and the data were analysed using thematic analysis. RESULTS: We identified three themes. 'Changes to Vision' explores participants' adaptation following cataract surgery. While several had problems with tasks relying on binocular vision, few found them bothersome and they resolved following second eye surgery. Participants described a trial and error approach to solving these problems rather than applying solutions suggested by their eyecare professionals. 'Prescription Restrictions' describes the long-term vision problems that pre-surgery myopic patients experienced as a consequence of becoming emmetropic following surgery and thus needing spectacles for reading and other close work activities, which they did not need before surgery. Very few reported that they had the information or time to make a decision regarding their post-operative correction. 'Information Needs' describes participant's responses to the post-surgical information they were given, and the unmet information need regarding when they can drive following surgery. CONCLUSION: The findings highlight the need for clinicians to provide information on adaptation effects, assist patients to select the refractive outcome that best suits their lifestyle, and provide clear advice about when patients can start driving again. Patients need to be provided with better guidance from clinicians and prescribing guidelines for clinicians would be beneficial, particularly for the period between first- and second-eye surgery
Visual Predictors of Postural Sway in Older Adults
Purpose: Accurate perception of body position relative to the environment through visual cues provides sensory input to the control of postural stability. This study explored which vision measures are most important for control of postural sway in older adults with a range of visual characteristics. Methods: Participants included 421 older adults (mean age = 72.6 ± 6.1), 220 with vision impairment associated with a range of eye diseases and 201 with normal vision. Participants completed a series of vision, cognitive, and physical function tests. Postural sway was measured using an electronic forceplate (HUR Labs) on a foam surface with eyes open. Linear regression analysis identified the strongest visual predictors of postu-ral sway, controlling for potential confounding factors, including cognitive and physical function. Results: In univariate regression models, unadjusted and adjusted for age, all of the vision tests were significantly associated with postural sway (P < 0.05), with the strongest predictor being visual motion sensitivity (standardized regression coefficient, β = 0.340; age-adjusted β = 0.253). In multiple regression models, motion sensitivity (β = 0.187), integrated binocular visual fields (β =−0.109), and age (β = 0.234) were the only significant visual predictors of sway, adjusted for confounding factors, explain-ing 23% of the variance in postural sway. Conclusions: Of the vision tests, visual motion perception and binocular visual fields were most strongly associated with postural stability in older adults with and without vision impairment. Translational Relevance: Findings provide insight into the visual contributions to postural stability in older adults and have implications for falls risk assessment
Arrhythmic Genotypes in Familial Dilated Cardiomyopathy: Implications for Genetic Testing and Clinical Management
Cardiac arrhythmias are frequently seen in patients with dilated cardiomyopathy (DCM) and can precipitate heart failure and death. In patients with non-ischaemic DCM, evidence for the benefit of an implantable cardioverter-defibrillator (ICD) for primary prevention of sudden cardiac death has recently been questioned. Algorithms devised to identify high-risk individuals who might benefit most from ICD implantation have focussed on clinical criteria with little attention paid to the underlying aetiology of DCM. Malignant ventricular arrhythmias often occur as a nonspecific consequence of DCM but can also be a primary manifestation of disease in heritable forms of DCM and may precede DCM onset. We undertook a literature search and identified 11 genes that have been associated with DCM and ventricular arrhythmias in multiple kindreds. Many of these genes fall into a diagnostic grey zone between left-dominant arrhythmogenic right ventricular cardiomyopathy and arrhythmic DCM. Genes associated predominantly with arrhythmic DCM included LMNA and SCN5A, as well as the more recently-reported DCM disease genes, RBM20, FLNC, and TTN. Recognition of arrhythmic DCM genotypes is important, as this may impact on clinical management. In particular, prophylactic ICD implantation and early referral for heart transplantation may be indicated in genotype-positive individuals. Collectively, these findings argue in favour of including genetic testing in standard-of-care management of familial DCM. Further studies in genotyped patient cohorts are required to establish the long-term health and economic benefits of this strategy
Mom-I don't want to hear it: Brain response to maternal praise and criticism in adolescents with major depressive disorder
Recent research has implicated altered neural response to interpersonal feedback as an important factor in adolescent depression, with existing studies focusing on responses to feedback from virtual peers. We investigated whether depressed adolescents differed from healthy youth in neural response to social evaluative feedback from mothers. During neuroimaging, twenty adolescents in a current episode of major depressive disorder (MDD) and 28 healthy controls listened to previously recorded audio clips of their own mothers' praise, criticism and neutral comments. Whole-brain voxelwise analyses revealed that MDD youth, unlike controls, exhibited increased neural response to critical relative to neutral clips in the parahippocampal gyrus, an area involved in episodic memory encoding and retrieval. Depressed adolescents also showed a blunted response to maternal praise clips relative to neutral clips in the parahippocampal gyrus, as well as areas involved in reward and self-referential processing (i.e. Ventromedial prefrontal cortex, precuneus, and thalamus/caudate). Findings suggest that maternal criticism may be more strongly encoded or more strongly activated during memory retrieval related to previous autobiographical instances of negative feedback from mothers in depressed youth compared to healthy youth. Furthermore, depressed adolescents may fail to process the reward value and self-relevance of maternal praise
Ultrafast phase-change logic device driven by melting processes.
The ultrahigh demand for faster computers is currently tackled by traditional methods such as size scaling (for increasing the number of devices), but this is rapidly becoming almost impossible, due to physical and lithographic limitations. To boost the speed of computers without increasing the number of logic devices, one of the most feasible solutions is to increase the number of operations performed by a device, which is largely impossible to achieve using current silicon-based logic devices. Multiple operations in phase-change-based logic devices have been achieved using crystallization; however, they can achieve mostly speeds of several hundreds of nanoseconds. A difficulty also arises from the trade-off between the speed of crystallization and long-term stability of the amorphous phase. We here instead control the process of melting through premelting disordering effects, while maintaining the superior advantage of phase-change-based logic devices over silicon-based logic devices. A melting speed of just 900 ps was achieved to perform multiple Boolean algebraic operations (e.g., NOR and NOT). Ab initio molecular-dynamics simulations and in situ electrical characterization revealed the origin (i.e., bond buckling of atoms) and kinetics (e.g., discontinuouslike behavior) of melting through premelting disordering, which were key to increasing the melting speeds. By a subtle investigation of the well-characterized phase-transition behavior, this simple method provides an elegant solution to boost significantly the speed of phase-change-based in-memory logic devices, thus paving the way for achieving computers that can perform computations approaching terahertz processing rates.This is the author's accepted manuscript. The final version is published by PNAS here: http://www.pnas.org/content/early/2014/08/27/1407633111.full.pdf+html?with-ds=yes
The male handicap: male-biased mortality explains skewed sex ratios in brown trout embryos
Juvenile sex ratios are often assumed to be equal for many species with genetic sex determination, but this has rarely been tested in fish embryos due to their small size and absence of sex-specific markers. We artificially crossed three populations of brown trout and used a recently developed genetic marker for sexing the offspring of both pure and hybrid crosses. Sex ratios (SR = proportion of males) varied widely one month after hatching ranging from 0.15 to 0.90 (mean = 0.39 ± 0.03). Families with high survival tended to produce balanced or male-biased sex ratios, but SR was significantly female-biased when survival was low, suggesting that males sustain higher mortality during development. No difference in SR was found between pure and hybrid families, but the existence of sire × dam interactions suggests that genetic incompatibility may play a role in determining sex ratios. Our findings have implications for animal breeding and conservation because skewed sex ratios will tend to reduce effective population size and bias selection estimates
Comparing open and minimally invasive surgical procedures for oesophagectomy in the treatment of cancer: the ROMIO (Randomised Oesophagectomy: Minimally Invasive or Open) feasibility study and pilot trial
Localised oesophageal cancer can be curatively treated with surgery (oesophagectomy) but the procedure is complex with a risk of complications, negative effects on quality of life and a recovery period of 6-9 months. Minimal-access surgery may accelerate recovery.The ROMIO (Randomised Oesophagectomy: Minimally Invasive or Open) study aimed to establish the feasibility of, and methodology for, a definitive trial comparing minimally invasive and open surgery for oesophagectomy. Objectives were to quantify the number of eligible patients in a pilot trial; develop surgical manuals as the basis for quality assurance; standardise pathological processing; establish a method to blind patients to their allocation in the first week post surgery; identify measures of postsurgical outcome of importance to patients and clinicians; and establish the main cost differences between the surgical approaches.Pilot parallel three-arm randomised controlled trial nested within feasibility work.Two UK NHS departments of upper gastrointestinal surgery.Patients aged ≥ 18 years with histopathological evidence of oesophageal or oesophagogastric junctional adenocarcinoma, squamous cell cancer or high-grade dysplasia, referred for oesophagectomy or oesophagectomy following neoadjuvant chemo(radio)therapy.Oesophagectomy, with patients randomised to open surgery, a hybrid open chest and minimally invasive abdomen or totally minimally invasive access.The primary outcome measure for the pilot trial was the number of patients recruited per month, with the main trial considered feasible if at least 2.5 patients per month were recruited.During 21 months of recruitment, 263 patients were assessed for eligibility; of these, 135 (51%) were found to be eligible and 104 (77%) agreed to participate, an average of five patients per month. In total, 41 patients were allocated to open surgery, 43 to the hybrid procedure and 20 to totally minimally invasive surgery. Recruitment is continuing, allowing a seamless transition into the definitive trial. Consequently, the database is unlocked at the time of writing and data presented here are for patients recruited by 31 August 2014. Random allocation achieved a good balance between the arms of the study, which, as a high proportion of patients underwent their allocated surgery (69/79, 87%), ensured a fair comparison between the interventions. Dressing patients with large bandages, covering all possible incisions, was successful in keeping patients blind while pain was assessed during the first week post surgery. Postsurgical length of stay and risk of adverse events were within the typical range for this group of patients, with one death occurring within 30 days among 76 patients. There were good completion rates for the assessment of pain at 6 days post surgery (88%) and of the patient-reported outcomes at 6 weeks post randomisation (74%).Rapid recruitment to the pilot trial and the successful refinement of methodology indicated the feasibility of a definitive trial comparing different approaches to oesophagectomy. Although we have shown a full trial of open compared with minimally invasive oesophagectomy to be feasible, this is necessarily based on our findings from the two clinical centres that we could include in this small preliminary study.Current Controlled Trials ISRCTN59036820.This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 20, No. 48. See the NIHR Journals Library website for further project information
The development of path integration: combining estimations of distance and heading
Efficient daily navigation is underpinned by path integration, the mechanism by which we use self-movement information to update our position in space. This process is well-understood in adulthood, but there has been relatively little study of path integration in childhood, leading to an underrepresentation in accounts of navigational development. Previous research has shown that calculation of distance and heading both tend to be less accurate in children as they are in adults, although there have been no studies of the combined calculation of distance and heading that typifies naturalistic path integration. In the present study 5-year-olds and 7-year-olds took part in a triangle-completion task, where they were required to return to the startpoint of a multi-element path using only idiothetic information. Performance was compared to a sample of adult participants, who were found to be more accurate than children on measures of landing error, heading error, and distance error. 7-year-olds were significantly more accurate than 5-year-olds on measures of landing error and heading error, although the difference between groups was much smaller for distance error. All measures were reliably correlated with age, demonstrating a clear development of path integration abilities within the age range tested. Taken together, these data make a strong case for the inclusion of path integration within developmental models of spatial navigational processing
Atomistic origin of the enhanced crystallization speed and n-type conductivity in Bi-doped Ge-Sb-Te phase-change materials
Phase-change alloys are the functional materials at the heart of an emerging digital-storage technology. The GeTe-Sb2Te3 pseudo-binary systems, in particular the composition Ge2Sb2Te5 (GST), are one of a handful of materials which meet the unique requirements of a stable amorphous phase, rapid amorphous-to-crystalline phase transition, and significant contrasts in optical and electrical properties between material states. The properties of GST can be optimized by doping with p-block elements, of which Bi has interesting effects on the crystallisation kinetics and electrical properties. We have carried out a comprehensive simulational study of Bi-doped GST, looking at trends in behavior and properties as a function of dopant concentration. Our results reveal how Bi integrates into the host matrix, and provide insight into its enhancement of the crystallisation speed. We propose a straightforward explanation for the reversal of the charge-carrier sign beyond a critical doping threshold. We also investigate how Bi affects the optical properties of GST. The microscopic insight from this study may assist in the future selection of dopants to optimize the phase-change properties of GST, and also of other PCMs, and the general methods employed in this work should be applicable to the study of related materials, e.g. doped chalcogenide glasses.This is the final published version. It's also available from Wiley at http://onlinelibrary.wiley.com/doi/10.1002/adfm.201401202/pdf
The egiin davaa prehistoric rupture, central mongolia: A large magnitude normal faulting earthquake on a reactivated fault with little cumulative slip located in a slowly deforming intraplate setting
The prehistoric Egiin Davaa earthquake rupture is well-preserved in late Quaternary deposits within the Hangay Mountains of central Mongolia. The rupture is expressed by a semicontinuous 80 km-long topographic scarp. Geomorphological reconstructions reveal a relatively constant scarp height of 4-4.5 m and a NW-directed slip vector. Previous researchers have suggested that the scarp's exceptional geomorphological preservation indicates that it may correspond to an earthquake that occurred in the region c. 500 years ago. However, we constrain the last rupture to have been at least 4 ka ago from morphological dating and < 7.4 ka ago based on radiocarbon dating from one of two palaeoseismic trenches. Our study shows that discrete earthquake ruptures, along with details such as the locations of partially infilled fissures, can be preserved for periods well in excess of 1000 years in the interior of Asia, providing an archive of fault movements that can be directly read from the Earth's surface over a timescale appropriate for the study of slowly deforming continental interiors. The Egiin Davaa rupture involved c. 8 m of slip which, along with the observations that it is largely unsegmented along its length and that the ratio of cumulative slip (c. 250 m) to fault length (c. 80 km) is small, suggests relatively recent reactivation of a pre-existing geological structure
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