9,449 research outputs found

    Lexico-semantic Impairment in a Case of HSVE to the Left Anterior Temporal Lobe

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    This study investigates the role of the left anterior temporal lobe (aTL) in semantics. Clinical and neuroscientific investigations propose the aTL bilaterally (BaTL), are implicated in semantics, based on findings that: (1) disruption to BaTL results in a multimodal semantic impairment, observed in semantic dementia (SD) and herpes-simplex-viral-encephalitis (HSVE); (2) impairment can be mimicked by inducing a “virtual lesion” (repetitive-transcranial-magnetic-stimulation) to BaTL in neurologically intact participants; (3) neuroimaging studies identify BaTL activation for semantic tasks (Fig 1, Lambon Ralph et al., 2012, for points 1-3). Anchored in this evidence is the assumption that semantic impairment will result from BaTL damage only. Recently, investigators have suggested a loss of semantic knowledge can result from LaTL damage. Using sensitive tests, this can be observed in chronic stroke (Schwartz et al., 2009) and temporal lobe resection for epilepsy patients (rTLE: Antonucci et al., 2008; Lambon Ralph et al., 2012). Of interest is the striking similarity of rTLE and very early stages of SD (when atrophy is left sided and overlaps with resection) – impairment is mild and the primary symptom is anomia and/or forgetfulness. This builds upon the possibility that a semantic weakness may result from a LaTL lesion. Whilst rTLE studies have provided insight into this notion, one must be cautious – pre-surgical seizures may initiate changes in brain organisation/normal development, and reorganisation of function could occur post-surgery. Chronic stroke studies are problematic since lesions are large and encompass other areas that may contribute to the impairment. Consequently, whether LaTL lesions results in semantic impairment is not entirely understood. The goal of the present case study was to initiate an investigation to determine whether semantic impairment is in fact present following LaTL lesion

    Mechanism of the Vasodilator Action of Pinacidil

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    The mechanism of the vasodilator action of pinacidil has been studied in rat mesenteric small arteries. The results show, first, that the use of flux studies to make measurements of ion permeability requires knowledge of the membrane potential, especially as regards K+ permeability. Second, the results confirm that the vasodilator effect of pinacidil is due to an increase in K+ permeability. Lastly, the results suggest that the K+ channels involved are sensitive to glibenclamide

    An unusual cause of acute abdominal pain – A case presentation

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    BACKGROUND: In 1983, Graham Hughes described a condition of Antiphospholipid Syndrome in which there was a danger of thrombosis. The condition is readily detectable by blood tests and, once diagnosed; the risk of further thrombosis can be significantly reduced by anticoagulation treatments. Affected groups of patients can be distinguished by a specific blood test – the detection of antiphospholipid antibody (Ref-1). Patients with Hughes syndrome have hypercoaguable state with a markedly increased risk of both arterial and venous thrombosis and there is temporal persistence of antibody positivity. CASE PRESENTATION: A 44-year-old woman was admitted under the acute surgical "take" with left sided abdominal pain radiating to her back. She had a history of borderline thyrotoxicosis in the early 1990s. She was on etonogestrel-releasing implants for contraception and there was no history of previous deep venous thrombosis. She was very tender, locally, over the left side of the abdomen. Investigations showed haemoglobin of 13.2 g/dl, white cell count of 19.9 10*9/L, and platelets 214 10*9/L with neutrophilia. Amylase and renal function tests were found to be normal. Liver function tests were deranged with Gamma GT 244 u/l (twice normal). An abdominal Ultrasound Scan suggested a possible splenic infarction, which was confirmed by a CT scan of her abdomen. Tests were carried out to investigate the possibility of a post thrombotic state. Coagulation risk factors for thrombosis were within the normal limits; Protein S 67 %(60–140), Protein C 103 % (72–146), Antithrombin 3 110 %(80–120) and Activated P C Resistance was 1.9(2.0–4.3). The Hams test was negative but the Anticardiolipin antibody test was positive. IgM level was 52 (normal is up to 10) and IgG was 18.8 (normal is up to 10). She also had border line APC Sensitivity 1.9 (2 to 4.3). Kaolin time 49 sec (70–120) Ktmix 64 sec (70–120), thyroid function test revealed TSH 0.32 mu/L, fT4 20.2 pmol/L (10–25). Subsequent determination of Anticardiolipin antibody was negative. Her symptoms were settled with the use of simple analgesia and she was discharged home with long-term anticoagulation medication. The INR target for long-term anticoagulation was aimed at >3. CONCLUSION: This case presented to us as an acute abdominal pain. Subsequent investigations revealed the presence of splenic infarction. Coagulation risk factors for thrombosis proved negative. Haematological investigations revealed the presence of anticardiolipin antibodies at the first instance but subsequent determinations were negative. Hence, it mimicked Hughes syndrome initially but the criteria for temporal persistence of anticardiolipin antibody was not fulfilled. Unusual surgical presentation of a thrombotic abnormality as abdominal pain due to splenic infarction

    Defect filtering for thermal expansion induced dislocations in III-V lasers on silicon

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    Epitaxially integrated III-V semiconductor lasers for silicon photonics have the potential to dramatically transform information networks, but currently, dislocations limit performance and reliability even in defect tolerant InAs quantum dot (QD) based lasers. Despite being below critical thickness, QD layers in these devices contain previously unexplained misfit dislocations, which facilitate non-radiative recombination. We demonstrate here that these misfit dislocations form during post-growth cooldown due to the combined effects of (1) thermal-expansion mismatch between the III-V layers and silicon and (2) precipitate and alloy hardening in the active region. By incorporating an additional sub-critical thickness, indium-alloyed misfit dislocation trapping layer, we leverage these mechanical hardening effects to our advantage, successfully displacing 95% of misfit dislocations from the QD layer in model structures. Unlike conventional dislocation mitigation strategies, the trapping layer reduces neither the number of threading dislocations nor the number of misfit dislocations. It simply shifts the position of misfit dislocations away from the QD layer, reducing the defects' impact on luminescence. In full lasers, adding a misfit dislocation trapping layer both above and below the QD active region displaces misfit dislocations and substantially improves performance: we measure a twofold reduction in lasing threshold currents and a greater than threefold increase in output power. Our results suggest that devices employing both traditional threading dislocation reduction techniques and optimized misfit dislocation trapping layers may finally lead to fully integrated, commercially viable silicon-based photonic integrated circuits.Comment: 9 pages, 6 figure

    The functional characteristics of optogenetic gene therapy for vision restoration

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    Optogenetic strategies to restore vision in patients blind from end-stage retinal degenerations aim to render remaining retinal neurons light-sensitive. We present an innovative combination of multi-electrode array recordings together with a complex pattern-generating light source as a toolset to determine the extent to which neural retinal responses to complex light stimuli can be restored following viral delivery of red-shifted channelrhodopsin in the retinally degenerated mouse. Our data indicate that retinal output level spatiotemporal response characteristics achieved by optogenetic gene therapy closely parallel those observed for normal mice but equally reveal important limitations, some of which could be mitigated using bipolar-cell targeted gene-delivery approaches. As clinical trials are commencing, these data provide important new information on the capacity and limitations of channelrhodopsin-based gene therapies. The toolset we established enables comparing optogenetic constructs and stem-cell-based techniques, thereby providing an efficient and sensitive starting point to identify future approaches for vision restoration

    The geochemistry and petrogenesis of the Paleoproterozoic du Chef dyke swarm, Québec, Canada

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    This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.The du Chef dyke swarm in southern Québec, Canada is composed of numerous northeast trending, greenschist-amphibolite facies, gabbronoritic dykes that crop out either side of the Grenville Front. The age of the du Chef swarm (2408 ± 3 Ga) has led previous authors to suggest a genetic link between the du Chef dykes and coeval swarms (including the Ringvassøy, Scourie, Widgemooltha and Sebanga) preserved on other Archean cratons. These now disparate dyke swarms are proposed to have formed in response to mantle plume-induced continental breakup during the early Proterozoic. This work represents the first geochemical study of the du Chef dykes and shows that the swarm evolved through fractional crystallisation of a tholeiitic parent magma that remained largely uncontaminated during its residence in, and ascent through, the crust. We also show that the primary magma for the du Chef swarm was derived through partial melting of an enriched region of the mantle, with a similar trace element composition to the modern-day HIMU reservoir and that the magma produced was significantly hotter than the ambient mantle at the time. We contend that the du Chef dykes are the product of early Proterozoic mantle plume magmatism and may help pinpoint an ancient hotspot centre that initiated continental break up along the margin of the Superior Craton at ∼2.4 Ga. Other dyke swarms proposed to be genetically linked with the du Chef dykes record a distinctly different petrogenetic history to that of the du Chef dykes, as evidenced by their more volcanic arc-like geochemical signature. These contrasting geochemical signatures in supposedly cogenetic continental tholeiitic rocks may be evidence of early Proterozoic mantle heterogeneity sampled by the rising du Chef mantle plume.This study forms part of a Ph.D. dissertation undertaken by T.J.R.C. at the University of Cardiff, United Kingdom. A. Okrugin's assistance in the field is acknowledged. J. Strongman, J. Fletcher and J. Pett are thanked for their permission of use of the petrographic equipment at Petrolab Ltd. L. Badham, A. Oldroyd, L. Woolley and P. Fisher are thanked for their help in preparation and analysis of samples. This is publication number 38 of the Large Igneous Provinces, Supercontinent Reconstruction, Resource Exploration Project (www.supercontinent.org)

    Are tibial angles measured with inertial sensors useful surrogates for frontal plane projection angles using 2-dimensional video analysis during single leg squat tasks? A reliability and agreement analysis in elite football (soccer) players

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    During single leg squats (SLS), tibial angle (TA) quantification using inertial measurement units (IMU) may offer a practical alternative to frontal plane projection angle (FPPA) measurement using 2-dimensional (2D) video analysis. This study determined: (i) the reliability of IMUs and 2D video analysis for TA measurement, and 2D video analysis for FPPA measurement; (ii) the agreement between IMU TA and both 2D video TA and FPPA measurements during single leg squats in elite footballers. 18 players were tested on consecutive days. Absolute TA (ATA) and relative TA (RTA) were measured with IMUs. ATA and FPPA were measured concurrently using 2D video analysis. Within-session reliability for all measurements varied across days (intraclass correlation coefficient (ICC) range=0.27–0.83, standard error of measurement (SEM) range=2.12–6.23°, minimal detectable change (MDC) range=5.87–17.26°). Between-sessions, ATA reliability was good for both systems (ICCs=0.70–0.74, SEMs=1.64–7.53°, MDCs=4.55–7.01°), while IMU RTA and 2D FPPA reliability ranged from poor to good (ICCs=0.39–0.72, SEMs=2.60–5.99°, MDCs=7.20–16.61°). All limits of agreement exceeded a 5° acceptability threshold. Both systems were reliable for between-session ATA, although agreement was poor. IMU RTA and 2D video FPPA reliability was variable. For SLS assessment, IMU derived TAs are not useful surrogates for 2D video FPPA measures in this population

    A randomized controlled trial of inhibitory control training for smoking cessation and reduction

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    This is the author accepted manuscript. The final version is available from the American Psychological Association via the DOI in this recordObjective: The high rates of illness and mortality associated with cigarette smoking necessitate the development of novel reduction and cessation treatments. Inhibitory control training (ICT) has recently emerged as a potentially efficacious intervention to reduce the consumption of alcohol and unhealthy food. This randomized controlled trial was the first to investigate the effect of Internet-delivered ICT on cigarette consumption in a community sample of heavy smokers. Method: For the present study, 107 adult smokers (mean age = 46.15 years; 57 female) who smoked a minimum of 10 cigarettes per day and met criteria for a moderate or severe tobacco use disorder were recruited. Participants were randomly allocated to receive go/no-go training in which either smoking stimuli (intervention) or nonsmoking stimuli (control) were paired with no-go signals and were instructed to complete 1 training session per day over a 2-week period. This trial was preregistered with the Australian and New Zealand Clinical Trials Registry (Trial ID: ACTRN12617000252314). Results: We found no significant differences between conditions on percentage of days abstinent or daily cigarette consumption, although there was a significant decrease in daily cigarette consumption across both conditions. Further, we found no significant moderating effects of impulsivity on the relationship between cigarette consumption and the 2 tasks. Conclusions: Although participants in both conditions reduced their daily cigarette consumption, the intervention task was no more successful than the control task was in achieving cigarette abstinence or reduction.Deakin Universit
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