2,086 research outputs found

    Electric-field-induced coherent coupling of the exciton states in a single quantum dot

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    The signature of coherent coupling between two quantum states is an anticrossing in their energies as one is swept through the other. In single semiconductor quantum dots containing an electron-hole pair the eigenstates form a two-level system that can be used to demonstrate quantum effects in the solid state, but in all previous work these states were independent. Here we describe a technique to control the energetic splitting of these states using a vertical electric field, facilitating the observation of coherent coupling between them. Near the minimum splitting the eigenstates rotate in the plane of the sample, being orientated at 45{\deg} when the splitting is smallest. Using this system we show direct control over the exciton states in one quantum dot, leading to the generation of entangled photon pairs

    Missense Mutation R338W in ARHGEF9 in a Family with X-linked Intellectual Disability with Variable Macrocephaly and Macro-Orchidism

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    Non-syndromal X-linked intellectual disability (NS-XLID) represents a broad group of clinical disorders in which ID is the only clinically consistent manifestation. Although in many cases either chromosomal linkage data or knowledge of the >100 existing XLID genes has assisted mutation discovery, the underlying cause of disease remains unresolved in many families. We report the resolution of a large family (K8010) with NS-XLID, with variable macrocephaly and macro-orchidism. Although a previous linkage study had mapped the locus to Xq12-q21, this region contained too many candidate genes to be analyzed using conventional approaches. However, X-chromosome exome sequencing, bioinformatics analysis and segregation analysis revealed a novel missense mutation (c.1012C>T; p.R338W) in ARHGEF9. This gene encodes collybistin (CB), a neuronal GDP-GTP exchange factor previously implicated in several cases of XLID, as well as clustering of gephyrin and GABAA receptors at inhibitory synapses. Molecular modeling of the CB R338W substitution revealed that this change results in the substitution of a long electropositive side-chain with a large non-charged hydrophobic side-chain. The R338W change is predicted to result in clashes with adjacent amino acids (K363 and N335) and disruption of electrostatic potential and local folding of the PH domain, which is known to bind phosphatidylinositol-3-phosphate (PI3P/PtdIns-3-P). Consistent with this finding, functional assays revealed that recombinant CB CB2SH3- (R338W) was deficient in PI3P binding and was not able to translocate EGFP-gephyrin to submembrane microaggregates in an in vitro clustering assay. Taken together, these results suggest that the R338W mutation in ARHGEF9 is the underlying cause of NS-XLID in this family

    Feasibility of vocal fold abduction and adduction assessment using cine-MRI

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    OBJECTIVE: Determine feasibility of vocal fold (VF) abduction and adduction assessment by cine magnetic resonance imaging (cine-MRI) METHODS: Cine-MRI of the VF was performed on five healthy and nine unilateral VF paralysis (UVFP) participants using an axial gradient echo acquisition with temporal resolution of 0.7 s. VFs were continuously imaged with cine-MRI during a 10-s period of quiet respiration and phonation. Scanning was repeated twice within an individual session and then once again at a 1-week interval. Asymmetry of VF position during phonation (VF phonation asymmetry, VFPa) and respiration (VF respiration asymmetry, VFRa) was determined. Percentage reduction in total glottal area between respiration and phonation (VF abduction potential, VFAP) was derived to measure overall mobility. An un-paired t-test was used to compare differences between groups. Intra-session, inter-session and inter-reader repeatability of the quantitative metrics was evaluated using intraclass correlation coefficient (ICC). RESULTS: VF position asymmetry (VFPa and VFRa) was greater (p=0.012; p=0.001) and overall mobility (VFAP) was lower (p=0.008) in UVFP patients compared with healthy participants. ICC of repeatability of all metrics was good, ranged from 0.82 to 0.95 except for the inter-session VFPa (0.44). CONCLUSION: Cine-MRI is feasible for assessing VF abduction and adduction. Derived quantitative metrics have good repeatability. KEY POINTS: • Cine-MRI is used to assess vocal folds (VFs) mobility: abduction and adduction. • New quantitative metrics are derived from VF position and abduction potential. • Cine-MRI able to depict the difference between normal and abnormal VF mobility. • Cine-MRI derived quantitative metrics have good repeatability

    Kisspeptin-neuron control of LH pulsatility and ovulation

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    Feedback from oestradiol (E2) plays a critical role in the regulation of major events in the physiological menstrual cycle including the release of gonadotrophins to stimulate follicular growth, and the mid-cycle luteinising hormone (LH) surge that leads to ovulation. E2 predominantly exerts its action via oestrogen receptor-alpha (ERα), however, as gonadotrophin releasing hormone (GnRH) neurons lack ERα, E2-feedback is posited to be indirectly mediated via upstream neurons. Kisspeptin (KP) is a neuropeptide expressed in hypothalamic KP-neurons that control GnRH secretion and plays a key role in the central mechanism regulating the hypothalamic-pituitary-gonadal (HPG) axis. In the rodent arcuate (ARC) nucleus, KP is co-expressed with Neurokinin B and Dynorphin; and thus, these neurons are termed ‘Kisspeptin-Neurokinin B-Dynorphin’ (KNDy) neurons. ARC KP-neurons function as the ‘GnRH pulse generator’ to regulate GnRH pulsatility, as well as mediating negative feedback from E2. A second KP neuronal population is present in the rostral periventricular area of the third ventricle (RP3V), which includes anteroventral periventricular (AVPV) nucleus and preoptic area neurons. These RP3V KP-neurons mediate positive feedback to induce the mid-cycle luteinising hormone (LH) surge and subsequent ovulation. Here, we describe the role of KP-neurons in these two regions in mediating this differential feedback from oestrogens. We conclude by considering reproductive diseases for which exploitation of these mechanisms could yield future therapies

    Vascular disrupting agent for neovascular age related macular degeneration: a pilot study of the safety and efficacy of intravenous combretastatin A-4 phosphate

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    BACKGROUND: This study was designed to assess the safety, tolerability, and efficacy of intravenous infusion of CA4P in patients with neovascular age-related macular degeneration (AMD). METHODS: Prospective, interventional, dose-escalation clinical trial. Eight patients with neovascular AMD refractory to at least 2 sessions of photodynamic therapy received CA4P at a dose of 27 or 36 mg/m2 as weekly intravenous infusion for 4 consecutive weeks. Safety was monitored by vital signs, ocular and physical examinations, electrocardiogram, routine laboratory tests, and collection of adverse events. Efficacy was assessed using retinal fluorescein angiography, optical coherence tomography, and best corrected visual acuity (BCVA). RESULTS: The most common adverse events were elevated blood pressure (46.7%), QTc prolongation (23.3%), elevated temperature (13.3%), and headache (10%), followed by nausea and eye injection (6.7%). There were no adverse events that were considered severe in intensity and none resulted in discontinuation of treatment. There was reduction of the excess foveal thickness by 24.15% at end of treatment period and by 43.75% at end of the two-month follow-up (p = 0.674 and 0.161, respectively). BCVA remained stable throughout the treatment and follow-up periods. CONCLUSIONS: The safety profile of intravenous CA4P was consistent with that reported in oncology trials of CA4P and with the class effects of vascular disruptive agents; however, the frequency of adverse events was different. There are evidences to suggest potential efficacy of CA4P in neovascular AMD. However, the level of systemic safety and efficacy indicates that systemic CA4P may not be suitable as an alternative monotherapy to current standard-of-care therapy

    Higher IL-10 levels are associated with less effective clearance of Plasmodium falciparum parasites

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    The implications of high levels of the immune regulatory cytokine IL-10 in Plasmodium falciparum malaria are unclear. IL-10 may down-regulate pro-inflammatory responses and also exacerbate disease by inhibiting anti-parasitic immune functions. To study possible inhibiting effects on parasite clearance, IL-10 plasma levels were determined in 104 Tanzanian children, 1 to 4 years old, with acute uncomplicated P. falciparum malaria, and analysed for association with parasite densities during 3 days of anti-malarial treatment. Higher baseline IL-10 plasma levels were associated with statistically significantly higher parasite densities after 24, 48 and 72 h of treatment. These associations could not be explained by differences in initial parasitaemia, temperature, age, sex or type of treatment. Induction of high IL-10 production might be a direct or indirect mechanism whereby the parasite evades the immune response

    The social cure of social prescribing: a mixed-methods study on the benefits of social connectedness on quality and effectiveness of care provision

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    Objectives: To assess the degree to which the ‘Social Cure’ model of psycho-social health captures the understandings and experiences of healthcare staff and patients in a Social Prescribing (SP) pathway and the degree to which these psycho-social processes predict the effect of the pathway on healthcare usage. Design: Mixed-method: Study 1: semi-structured interviews, Study 2: longitudinal survey. Setting: An English SP pathway delivered between 2017 and 2019. Participants: Study 1: GPs (n=7), healthcare providers (n=9) and service users (n=19). Study 2: 630 patients engaging with SP pathway at a four-month follow-up after initial referral assessment. Intervention: Chronically ill patients experiencing loneliness referred onto SP pathway and meeting with a Health Coach and/or Link Worker, with possible further referral to existing or newly-created relevant third-sector groups. Main Outcome Measure: Study 1: Health providers and users’ qualitative perspectives on the experience of the pathway and social determinants of health. Study 2: Patients’ primary care usage. Results: Healthcare providers recognised the importance of social factors in determining patient well-being, and reason for presentation at primary care. They viewed SP as a potentially effective solution to such problems. Patients valued the different social relationships they created through the SP pathway, including those with link workers, groups, and community. Group memberships quantitatively predicted primary care usage, and this was mediated by increases in community belonging, and reduced loneliness. Conclusions: Methodological triangulation offers robust conclusions that ‘Social Cure’ processes explain the efficacy of SP, which can reduce primary care usage through increasing social connectedness (group membership and community belonging) and reducing loneliness. Recommendations for integrating Social Cure processes into SP initiatives are discussed. Strengths and limitations of this study The strengths of this study: a. It identifies mechanisms that underlie effective Social Prescribing interventions. b. It identifies mechanisms that enable more appropriate use of primary care services. c. It reports the most comprehensive multi-perspective evaluation of an NHS model of Social Prescribing to date, with accounts from General Practitioners, Link Workers, Health Coaches and Patients. The limitations of this study: a. The results observed in our longitudinal analysis are short-term and are likely to develop further over longer time-periods, though observing benefits after such a short time is promising. b. The specific characteristics of this sample (adults with complex health needs from across the socio-economic spectrum, living in a relatively affluent area) need to be borne in mind when considering the applicability of SP to other populations

    The adaptation of the Affective Norms for English Words (ANEW) for European Portuguese

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    This study presents the adaptation of the Affective Norms for English Words (ANEW; Bradley & Lang, 1999a) for European Portuguese (EP). The EP adaptation of the ANEW was based on the affective ratings made by 958 college students who were EP native speakers. Participants assessed about 60 words by considering the affective dimensions of valence, arousal, and dominance, using the Self-Assessment Manikin (SAM) in either a paper-and-pencil and a web survey procedures. Results of the adaptation of the ANEW for EP are presented. Furthermore, the differences between EP, American (Bradley & Lang, 1999a), and Spanish (Redondo, Fraga, Padrón, & Comesaña, 2007) standardizations were explored. Results showed that the ANEW words were understood in a similar way by EP, American, and Spanish subjects, although some sex and cross-cultural differences were observed. The EP adaptation of the ANEW is shown to be a valid and useful tool that will allow researchers to control and/or manipulate the affective properties of stimuli as well as to develop cross-linguistic studies. The normative values of EP adaptation of the ANEW can be downloaded at http://brm.psychonomic-journals.org/content/supplemental.COMPETE - Programa Operacional Factores de CompetitividadeFundo Europeu de Desenvolvimento Regional - FEDERQuadro de Referência Estratégico Nacional - QRENFundação para a Ciência e a Tecnologia (FCT) - research project “Procura Palavras (P-Pal ): A software program for deriving objective and subjective psycholinguistic indices for European Portuguese words

    Exploring pig trade patterns to inform the design of risk-based disease surveillance and control strategies

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    An understanding of the patterns of animal contact networks provides essential information for the design of risk-based animal disease surveillance and control strategies. This study characterises pig movements throughout England and Wales between 2009 and 2013 with a view to characterising spatial and temporal patterns, network topology and trade communities. Data were extracted from the Animal and Plant Health Agency (APHA)’s RADAR (Rapid Analysis and Detection of Animal-related Risks) database, and analysed using descriptive and network approaches. A total of 61,937,855 pigs were moved through 872,493 movements of batches in England and Wales during the 5-year study period. Results show that the network exhibited scale-free and small-world topologies, indicating the potential for diseases to quickly spread within the pig industry. The findings also provide suggestions for how risk-based surveillance strategies could be optimised in the country by taking account of highly connected holdings, geographical regions and time periods with the greatest number of movements and pigs moved, as these are likely to be at higher risk for disease introduction. This study is also the first attempt to identify trade communities in the country, information which could be used to facilitate the pig trade and maintain disease-free status across the country in the event of an outbreak
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