Fast Scramblers Of Small Size

We investigate various geometrical aspects of the notion of `optical depth' in the thermal atmosphere of black hole horizons. Optical depth has been proposed as a measure of fast-crambling times in such black hole systems, and the associated optical metric suggests that classical chaos plays a leading role in the actual scrambling mechanism. We study the behavior of the optical depth with the size of the system and find that AdS/CFT phase transitions with topology change occur naturally as the scrambler becomes smaller than its thermal length. In the context of detailed AdS/CFT models based on D-branes, T-duality implies that small scramblers are described in terms of matrix quantum mechanics.Comment: 14 pages, 3 figures. Added reference

Polymorphous low-grade adenocarcinoma of the tongue: a case report

<p>Abstract</p> <p>Introduction</p> <p>Polymorphous low-grade adenocarcinoma is a distinct neoplasm of the salivary gland composed of luminal and non-luminal tumor cells admixed in varying proportions. Its resemblance to lobular carcinoma of the breast had led to its earlier nomenclature of 'terminal duct carcinoma'. Most patients present with an asymptomatic mass in the hard palate. In rare cases, the mass can also occur in the tongue. We report an unusual case of polymorphous low-grade adenocarcinoma at the base of tongue.</p> <p>Case presentation</p> <p>A 47-year-old Asian Caucasian woman presented with a painless swelling at the right lateral border of the tongue with an intact overlying mucosa. There were no other associated complaints. The lesion was excised and subjected to histopathological examination that revealed an interesting and unusual morphology of polymorphous low-grade adenocarcinoma.</p> <p>Conclusion</p> <p>Polymorphous low-grade adenocarcinoma is a well-defined entity in the minor salivary glands. Its occurrence in the tongue is rare with very few cases reported in the literature. It is a malignant neoplasm with low aggressiveness and it is thus important to identify and treat it accordingly.</p

A review of RCTs in four medical journals to assess the use of imputation to overcome missing data in quality of life outcomes

Background: Randomised controlled trials (RCTs) are perceived as the gold-standard method for evaluating healthcare interventions, and increasingly include quality of life (QoL) measures. The observed results are susceptible to bias if a substantial proportion of outcome data are missing. The review aimed to determine whether imputation was used to deal with missing QoL outcomes. Methods: A random selection of 285 RCTs published during 2005/6 in the British Medical Journal, Lancet, New England Journal of Medicine and Journal of American Medical Association were identified. Results: QoL outcomes were reported in 61 (21%) trials. Six (10%) reported having no missing data, 20 (33%) reported ≤ 10% missing, eleven (18%) 11%–20% missing, and eleven (18%) reported >20% missing. Missingness was unclear in 13 (21%). Missing data were imputed in 19 (31%) of the 61 trials. Imputation was part of the primary analysis in 13 trials, but a sensitivity analysis in six. Last value carried forward was used in 12 trials and multiple imputation in two. Following imputation, the most common analysis method was analysis of covariance (10 trials). Conclusion: The majority of studies did not impute missing data and carried out a complete-case analysis. For those studies that did impute missing data, researchers tended to prefer simpler methods of imputation, despite more sophisticated methods being available.The Health Services Research Unit is funded by the Chief Scientist Office of the Scottish Government Health Directorate. Shona Fielding is also currently funded by the Chief Scientist Office on a Research Training Fellowship (CZF/1/31)

A review of RCTs in four medical journals to assess the use of imputation to overcome missing data in quality of life outcomes

Peer reviewedPublisher PD

Interactions between Connected Half-Sarcomeres Produce Emergent Mechanical Behavior in a Mathematical Model of Muscle

Most reductionist theories of muscle attribute a fiber's mechanical properties to the scaled behavior of a single half-sarcomere. Mathematical models of this type can explain many of the known mechanical properties of muscle but have to incorporate a passive mechanical component that becomes ∼300% stiffer in activating conditions to reproduce the force response elicited by stretching a fast mammalian muscle fiber. The available experimental data suggests that titin filaments, which are the mostly likely source of the passive component, become at most ∼30% stiffer in saturating Ca2+ solutions. The work described in this manuscript used computer modeling to test an alternative systems theory that attributes the stretch response of a mammalian fiber to the composite behavior of a collection of half-sarcomeres. The principal finding was that the stretch response of a chemically permeabilized rabbit psoas fiber could be reproduced with a framework consisting of 300 half-sarcomeres arranged in 6 parallel myofibrils without requiring titin filaments to stiffen in activating solutions. Ablation of inter-myofibrillar links in the computer simulations lowered isometric force values and lowered energy absorption during a stretch. This computed behavior mimics effects previously observed in experiments using muscles from desmin-deficient mice in which the connections between Z-disks in adjacent myofibrils are presumably compromised. The current simulations suggest that muscle fibers exhibit emergent properties that reflect interactions between half-sarcomeres and are not properties of a single half-sarcomere in isolation. It is therefore likely that full quantitative understanding of a fiber's mechanical properties requires detailed analysis of a complete fiber system and cannot be achieved by focusing solely on the properties of a single half-sarcomere

Experiences of families post treatment for childhood brain tumours during medical clinic consultations regarding health‐related quality of life, unmet needs and communication barriers: A qualitative exploration

This is the final version. Available on open access from Wiley via the DOI in this recordData availability statement: Research data are not shared.Background Many studies highlight poor health-related quality of life (HRQoL) in children treated for brain tumours and their parents. However, little is known about the extent to which their informational, healthcare and communication needs regarding HRQoL are met during medical outpatient consultations. Aim To explore the experiences of families regarding communication with physicians about HRQoL issues during consultations after treatment for childhood brain tumours. Methods Interviews were conducted with 18 families of children and adolescents aged 8–17 years after completion of brain tumour treatment. Participants had completed treatment within the last 5 years and were receiving regular outpatient follow-up care. Thematic analysis was undertaken using the Framework Method. Results Five main themes were identified: (i) unmet emotional and mental health needs; (ii) double protection; (iii) unmet information needs; (iv) communication barriers within consultations; and (v) finding a new normal. Conclusion There was a need to improve communication between clinicians and these families, improve information provision, and overcome barriers to conversing with children within these outpatient consultations. Children and their parents should be supported to voice their current needs and concerns regarding their HRQoL. These findings will inform further development of the UK version of the ‘KLIK’ patient- and parent-reported outcome (PROM) portal.Brain Tumour Charit

Systematic review: measurement properties of patient-reported outcome measures evaluated with childhood brain tumor survivors or other acquired brain injury

This is the author accepted manuscript. The final version is available from Oxford University Press via the DOI in this recordBackground Survivors of childhood brain tumors or other acquired brain injury (ABI) are at risk of poor health-related quality of life (HRQoL); its valid and reliable assessment is essential to evaluate the effect of their illness on their lives. The aim of this review was to critically appraise psychometric properties of patient-reported outcome measures (PROMs) of HRQoL for these children, to be able to make informed decisions about the most suitable PROM for use in clinical practice. Methods We searched MEDLINE, EMBASE, and PsycINFO for studies evaluating measurement properties of HRQoL PROMs in children treated for brain tumors or other ABI. Methodological quality of relevant studies was evaluated using the consensus-based standards for the selection of health status measurement instruments checklist. Results Eight papers reported measurement properties of 4 questionnaires: Health Utilities Index (HUI), PedsQL Core and Brain Tumor Modules, and Child and Family Follow-up Survey (CFFS). Only the CFFS had evidence of content and structural validity. It also demonstrated good internal consistency, whereas both PedsQL modules had conflicting evidence regarding this. Conflicting evidence regarding test-retest reliability was reported for the HUI and PedsQL Core Module only. Evidence of measurement error/precision was favorable for HUI and CFFS and absent for both PedsQL modules. All 4 PROMs had some evidence of construct validity/hypothesis testing but no evidence of responsiveness to change. Conclusions Valid and reliable assessment is essential to evaluate impact of ABI on young lives. However, measurement properties of PROMs evaluating HRQoL appropriate for this population require further evaluation, specifically construct validity, internal consistency, and responsiveness to change.The Brain Tumour Charit

Dark-field tomography of an attenuating object using intrinsic x-ray speckle tracking.

Purpose: We investigate how an intrinsic speckle tracking approach to speckle-based x-ray imaging is used to extract an object's effective dark-field (DF) signal, which is capable of providing object information in three dimensions. Approach: The effective DF signal was extracted using a Fokker-Planck type formalism, which models the deformations of illuminating reference beam speckles due to both coherent and diffusive scatter from the sample. Here, we assumed that (a) small-angle scattering fans at the exit surface of the sample are rotationally symmetric and (b) the object has both attenuating and refractive properties. The associated inverse problem of extracting the effective DF signal was numerically stabilized using a "weighted determinants" approach. Results: Effective DF projection images, as well as the DF tomographic reconstructions of the wood sample, are presented. DF tomography was performed using a filtered back projection reconstruction algorithm. The DF tomographic reconstructions of the wood sample provided complementary, and otherwise inaccessible, information to augment the phase contrast reconstructions, which were also computed. Conclusions: An intrinsic speckle tracking approach to speckle-based imaging can tomographically reconstruct an object's DF signal at a low sample exposure and with a simple experimental setup. The obtained DF reconstructions have an image quality comparable to alternative x-ray DF techniques