1,020 research outputs found

    On the Viability of Minimal Neutrinophilic Two-Higgs-Doublet Models

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    We study the constraints that electroweak precision data can impose, after the discovery of the Higgs boson by the LHC, on neutrinophilic two-Higgs-doublet models which comprise one extra SU(2)×U(1)SU(2)\times U(1) doublet and a new symmetry, namely a spontaneously broken Z2\mathbb{Z}_2 or a softly broken global U(1)U(1). In these models the extra Higgs doublet, via its very small vacuum expectation value, is the sole responsible for neutrino masses. We find that the model with a Z2\mathbb{Z}_2 symmetry is basically ruled out by electroweak precision data, even if the model is slightly extended to include extra right-handed neutrinos, due to the presence of a very light scalar. While the other model is still perfectly viable, the parameter space is considerably constrained by current data, specially by the TT parameter. In particular, the new charged and neutral scalars must have very similar masses.Comment: 22 pages, 3 figures, references and comments added, conclusions unchanged, matches version to appear in JHE

    Simultaneous conduction and valence band quantisation in ultra-shallow, high density doping profiles in semiconductors

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    We demonstrate simultaneous quantisation of conduction band (CB) and valence band (VB) states in silicon using ultra-shallow, high density, phosphorus doping profiles (so-called Si:P δ\delta-layers). We show that, in addition to the well known quantisation of CB states within the dopant plane, the confinement of VB-derived states between the sub-surface P dopant layer and the Si surface gives rise to a simultaneous quantisation of VB states in this narrow region. We also show that the VB quantisation can be explained using a simple particle-in-a-box model, and that the number and energy separation of the quantised VB states depend on the depth of the P dopant layer beneath the Si surface. Since the quantised CB states do not show a strong dependence on the dopant depth (but rather on the dopant density), it is straightforward to exhibit control over the properties of the quantised CB and VB states independently of each other by choosing the dopant density and depth accordingly, thus offering new possibilities for engineering quantum matter.Comment: 5 pages, 2 figures and supplementary materia

    Classical and quantum spinor cosmology with signature change

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    We study the classical and quantum cosmology of a universe in which the matter source is a massive Dirac spinor field and consider cases where such fields are either free or self-interacting. We focus attention on the spatially flat Robertson-Walker cosmology and classify the solutions of the Einstein-Dirac system in the case of zero, negative and positive cosmological constant Λ\Lambda. For Λ<0\Lambda<0, these solutions exhibit signature transitions from a Euclidean to a Lorentzian domain. In the case of massless spinor fields it is found that signature changing solutions do not exist when the field is free while in the case of a self-interacting spinor field such solutions may exist. The resulting quantum cosmology and the corresponding Wheeler-DeWitt equation are also studied for both free and self interacting spinor fields and closed form expressions for the wavefunction of the universe are presented. These solutions suggest a quantization rule for the energy.Comment: 13 pages, 4 figure

    Opportunity cost determines free-operant action initiation latency and predicts apathy

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    Background Apathy, a disabling and poorly understood neuropsychiatric symptom, is characterised by impaired self-initiated behaviour. It has been hypothesised that the opportunity cost of time (OCT) may be a key computational variable linking self-initiated behaviour with motivational status. OCT represents the amount of reward which is foregone per second if no action is taken. Using a novel behavioural task and computational modelling, we investigated the relationship between OCT, self-initiation and apathy. We predicted that higher OCT would engender shorter action latencies, and that individuals with greater sensitivity to OCT would have higher behavioural apathy. Methods We modulated the OCT in a novel task called the 'Fisherman Game', Participants freely chose when to self-initiate actions to either collect rewards, or on occasion, to complete non-rewarding actions. We measured the relationship between action latencies, OCT and apathy for each participant across two independent non-clinical studies, one under laboratory conditions (n = 21) and one online (n = 90). 'Average-reward' reinforcement learning was used to model our data. We replicated our findings across both studies. Results We show that the latency of self-initiation is driven by changes in the OCT. Furthermore, we demonstrate, for the first time, that participants with higher apathy showed greater sensitivity to changes in OCT in younger adults. Our model shows that apathetic individuals experienced greatest change in subjective OCT during our task as a consequence of being more sensitive to rewards. Conclusions Our results suggest that OCT is an important variable for determining free-operant action initiation and understanding apathy

    Nano-Size Layered Manganese-Calcium Oxide as an Efficient and Biomimetic Catalyst for Water Oxidation Under Acidic Conditions: Comparable To Platinum

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    Inspired by Nature's catalyst, a nano-size layered manganese-calcium oxide showed a low overvoltage for water oxidation in acidic solutions, which is comparable to platinum.Institute for Advanced Studies in Basic Sciences and the National Elite FoundationUS Department of Energy, Office of Basic Energy Sciences, Division of Chemical, Geochemical and Biological Sciences DE-FG02-86ER13622, DE-FG0209ER16119Russian Foundation for Basic Research 11-04-01389a, 12-0492101a, 13-04-92711aMolecular and Cell Biology Programs of the Russian Academy of SciencesCenter for Electrochemistr

    Movement disorders associated with expansions and intermediate repeats in the C9orf72 gene

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    Measuring the Weak Mixing Angle in the DUNE Near Detector Complex

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    The planned DUNE experiment will have excellent sensitivity to the vector and axial couplings of the electron to the ZZ-boson via precision measurements of neutrino--electron scattering. We investigate the sensitivity of DUNE-PRISM, a movable near detector in the direction perpendicular to the beam line, and find that it will qualitatively impact our ability to constrain the weak couplings of the electron. We translate these neutrino--electron scattering measurements into a determination of the weak mixing angle at low scales and estimate that, with seven years of data taking, the DUNE near-detector can be used to measure sin2θW\sin^2\theta_W with about 2\% precision. We also discuss the impact of combining neutrino--electron scattering data with neutrino trident production at DUNE-PRISM.Comment: 6 pages, 4 figures, 1 Table. Improved analysis, added supplemental material, conclusions unchange

    Canonical wave packets in quantum cosmology

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    We discuss the construction of wave packets resulting from the solutions of a class of Wheeler-DeWitt equations in Robertson-Walker type cosmologies, for arbitrary curvature. We show that there always exists a ``canonical initial slope" for a given initial wave function, which optimizes some desirable properties of the resulting wave packet, most importantly good classical-quantum correspondence. This can be properly denoted as a canonical wave packet. We introduce a general method for finding these canonical initial slopes which is generalization of our earlier work.Comment: 19 pages, 8 figure

    A quantum cosmology and discontinuous signature changing classical solutions

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    We revisit the classical and quantum cosmology of a universe in which a self interacting scalar field is coupled to gravity with a flat FRW type metric undergoing continuous signature transition. We arrange for quantum cosmologically allowed discontinuity in the classical solutions at the signature changing hypersurface, provided these solutions be dual in some respects. This may be of some importance in the study of early universe within the signature changing scenarios.Comment: 11 pages, Latex, title and abstract changed, some cghanges in the text, to appear in GR

    The effects of alpha-lipoic acid supplementation on glucose control and lipid profiles among patients with metabolic diseases: A systematic review and meta-analysis of randomized controlled trials

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    Abstract Objective This systematic review and meta-analysis of randomized controlled trials (RCTs) was performed to summarize the effect of alpha-lipoic acid (ALA) supplementation on glycemic control and lipid profiles among patients with metabolic diseases. Methods We searched the following databases till October 2017: MEDLINE, EMBASE, Web of Science and Cochrane Central Register of Controlled Trials. The relevant data were extracted and assessed for quality of the studies according to the Cochrane risk of bias tool. Data were pooled using the inverse variance method and expressed as standardized mean difference (SMD) with 95% confidence intervals (95% CI). Heterogeneity between studies was assessed by the Cochran Q statistic and I-squared tests (I2). Twenty-four studies were included in the meta-analyses. Results The findings of this meta-analysis showed that ALA supplementation among patients with metabolic diseases significantly decreased fasting glucose (SMD -0.54; 95% CI, −0.89, –0.19; P = 0.003), insulin (SMD –1.01; 95% CI, −1.70, −0.31; P = 0.006), homeostasis model assessment of insulin resistance (SMD -0.76; 95% CI, −1.15, –0.36; P < 0.001) and hemoglobin A1c (SMD –1.22; 95% CI, −2.01, –0.44; P = 0.002), triglycerides (SMD –0.58; 95% CI, −1.00, −0.16; P = 0.006), total- (SMD –0.64; 95% CI, −1.01, −0.27; P = 0.001), low density lipoprotein-cholesterol (SMD –0.44; 95% CI, −0.76, −0.11; P = 0.008). We found no detrimental effect of ALA supplementation on high density lipoprotein-cholesterol (HDL-cholesterol) levels (SMD 0.57; 95% CI, −0.14, 1.29; P = 0.11). Conclusions Overall, the current meta-analysis demonstrated that ALA administration may lead to an improvement in glucose homeostasis parameters and lipid profiles except HDL-cholesterol levels. Keywords: Meta-analysis Lipid profiles Glycemic control Alpha-lipoic acid
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