1,859 research outputs found

    On the evolution of an entangled lepton-neutrino pair

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    The evolution of the entangled muon-neutrino system emerging from charged pion decay is explored both in vacuum and in matter. The study is based on a Weisskopf-Wigner type wave-packet description. Explicit formulae are derived displaying modulation and attenuation of the oscillations due to additional time scales characterising the production process. The case of neutrinos disentangled due to the detection of the muon is also considered

    Signatures from an extra-dimensional seesaw model

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    We study the generation of small neutrino masses in an extra-dimensional model, where right-handed neutrinos are allowed to propagate in the extra dimension, while the Standard Model particles are confined to a brane. Motivated by the fact that extra-dimensional models are non-renormalizable, we truncate the Kaluza-Klein towers at a maximal extra-dimensional momentum. The structure of the bulk Majorana mass term, motivated by the Sherk-Schwarz mechanism, implies that the right-handed Kaluza-Klein neutrinos pair to form Dirac neutrinos, except for a number of unpaired Majorana neutrinos at the top of each tower. These heavy Majorana neutrinos are the only sources of lepton number breaking in the model, and similarly to the type-I seesaw mechanism, they naturally generate small masses for the left-handed neutrinos. The lower Kaluza-Klein modes mix with the light neutrinos, and the mixing effects are not suppressed with respect to the light-neutrino masses. Compared to conventional fermionic seesaw models, such mixing can be more significant. We study the signals of this model at the Large Hadron Collider, and find that the current low-energy bounds on the non-unitarity of the leptonic mixing matrix are strong enough to exclude an observation.Comment: 17 pages, 3 figures, REVTeX4. Final version published in Phys. Rev.

    Effective communications on invasive alien species: Identifying communication needs of Swedish domestic garden owners

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    Invasive alien species threaten biodiversity with domestic gardens acting as a major pathway for the introduction of alien species. Even though the Nordic region is not currently a hotspot for biological invasions, the number of invasions in the Nordic area has been predicted to increase due to climate change. Given a time lag between introduction and invasion, many non-invasive horticultural alien species already introduced into gardens may become invasive in the future. This study aimed to identify the communication needs of Swedish garden owners regarding their management of invasive alien species. A survey among domestic garden owners, informed by topic specialists and local area experts, and interviews with garden owners were conducted in three different bio-climatic areas in a latitudinal gradient across Sweden. The questions targeted invasive alien species and their relations to biodiversity loss and climate change, as well as measures taken to control these species. Analysing the survey data collected in relation to measures taken to control invasive species, Bayesian Additive Regression Tree (BART) modelling was used to identify geographically varying communication needs of the domestic garden owners. In all study areas, the garden owners' measures taken to control invasive alien species were correlated with their strength of beliefs in having experienced local biodiversity loss. A majority of the garden owners were, moreover, uncertain about the impact of climate change on the invasiveness of alien species. In addition, the garden owners' capacity for identifying invasive alien species was often in need of improvement, in particular with respect to the species Impatiens glandulifera, Reynoutria japonica and Rosa rugosa. The results suggest that the evidence-based guidelines for effective communications we developed, have the potential to help communicators meet the local communication needs of garden owners across Sweden, in relation to the management of invasive alien garden species

    EURONU WP6 2009 yearly report: Update of the physics potential of Nufact, superbeams and betabeams

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    Many studies in the last ten years have shown that we can measure the unknown angle theta13, discover leptonic CP violation and determine the neutrino hierarchy in more precise neutrino oscillation experiments, searching for the subleading channel nue -> numu in the atmospheric range. In this first report of WP6 activities the following new results are reviewed: (1) Re-evaluation of the physics reach of the upcoming generation of experiments to measure theta13 and delta; (2) New tools to explore a larger parameter space as needed beyond the standard scenario; (3) Neutrino Factory: (a) evaluation of the physics reach of a Nufact regards sterile neutrinos; (b) evaluation of the physics reach of a Nufact as regards non-standard interactions; (c) evaluation of the physics reach of a Nufact as regards violation of unitarity; (d) critical assessment on long baseline tau-detection at Nufact; (e) new physics searches at a near detector in a Nufact; (4) Beta-beams: (a) choice of ions and location for a gamma = 100 CERN-based beta-beam; (b) re-evaluation of atmospheric neutrino background for the gamma = 100 beta-beam scenario; (c) study of a two baseline beta-beam; (d) measuring absolute neutrino mass with beta-beams; (e) progress on monochromatic beta-beams; (5) Update of the physics potential of the SPL super-beam. Eventually, we present an updated comparison of the sensitivity to theta13, delta and the neutrino mass hierarchy of several of the different proposed facilities.Comment: 2009 Yearly report of the Working Package 6 (Physics) of the EUROnu FP7 EU project. 55 pages, 21 figures

    Amyloid mis-metabolism in idiopathic normal pressure hydrocephalus

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    BACKGROUND: Patients with idiopathic normal pressure hydrocephalus (iNPH) have reduced cerebrospinal fluid (CSF) concentrations of amyloid-β (Aβ) and α- and β-cleaved soluble forms of amyloid precursor protein (sAPPα and sAPPβ). The aims of this study were to examine if changes could also be seen in the CSF for secreted metabolites of APP-like protein 1 (APLP1) and to explore the prognostic value of amyloid-related CSF biomarkers, as well as markers of neuronal injury and astroglial activation, as regards to clinical outcome after shunt surgery. METHODS: Twenty patients diagnosed with iNPH, 10 improved and 10 unchanged by shunt surgery, and 20 neurologically healthy controls were included. All patients were examined clinically prior to surgery and at 6-month follow-up after surgery using the iNPH scale. Lumbar puncture was performed pre-operatively. CSF samples were analyzed for neurofilament light (NFL), Aβ isoforms Aβ38, Aβ40 and Aβ42, sAPPα, sAPPβ, APLP1 β-derived peptides APL1β25, APL1β 27 and APL1β 28 and YKL40 by immunochemical methods. RESULTS: The concentrations of all soluble forms of APP, all Aβ isoforms and APL1β28 were lower, whilst APL1β25 and APL1β27 were higher in the CSF of iNPH patients compared to controls. There was no difference in biomarker concentrations between patients who improved after surgery and those who remained unchanged. CONCLUSIONS: The reduced CSF concentrations of Aβ38, Aβ40, Aβ42, sAPPα and sAPPβ suggest that APP expression could be downregulated in iNPH. In contrast, APLP1 concentration in the CSF seems relatively unchanged. The increase of APL1β25 and APL1β27 in combination with a slight decreased APL1β28 could be caused by more available γ-secretase due to reduced availability of its primary substrate, APP. The data did not support the use of these markers as indicators of shunt responsiveness

    CXCL13 in patients with facial palsy caused by varicella zoster virus and Borrelia burgdorferi: a comparative study

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    High cerebrospinal fluid (CSF) concentrations of the chemokine CXCL13 have been associated with Lyme neuroborreliosis (LNB), and have recently been studied as a potential diagnostic marker. It has proven difficult to establish a reliable diagnostic cut-off, possibly in part due to heterogenicity of case–control groups. Our purpose was to investigate CSF CXCL13 concentrations in patients with similar clinical presentations, facial palsy. We retrospectively included patients with facial palsy associated with LNB (n = 21), or varicella zoster virus (VZV) (n = 26). Median CXCL13 concentrations were significantly higher in patients with LNB facial palsy compared to VZV facial palsy. Receiver-operating characteristic analyses yielded an optimal cut-off concentration at 34.5 pg/mL (sensitivity 85.7%, specificity of 84.6%), lower than that in previous studies. Although the analysis has potential, it is still not adequately established that CXCL13 provides additional, clinically useful, diagnostic information over current recommendations

    Preclinical amyloid pathology biomarker positivity: effects on tau pathology and neurodegeneration

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    Brain autopsy and biomarker studies indicate that the pathology of Alzheimer's disease (AD) is initiated at least 10-20 years before clinical symptoms. This provides a window of opportunity to initiate preventive treatment. However, this emphasizes the necessity for biomarkers that identify individuals at risk for developing AD later in life. In this cross-sectional study, originating from three epidemiologic studies in Sweden (n=1428), the objective was to examine whether amyloid pathology, as determined by low cerebrospinal fluid (CSF) concentration of the 42 amino acid form of β-amyloid (Aβ42), is associated with biomarker evidence of other pathological changes in cognitively healthy elderly. A total of 129 patients were included and CSF levels of Aβ42, total tau, tau phosphorylated at threonine 181 (p-tau), neurogranin, VILIP-1, VEGF, FABP3, Aβ40, neurofilament light, MBP, orexin A, BDNF and YKL-40 were measured. Among these healthy elderly, 35.6% (N=46) had CSF Aβ42 levels below 530 pg ml(-1). These individuals displayed significantly higher CSF concentrations of t-tau (P<0.001), p-tau (181) (P<0.001), neurogranin (P=0.009) and FABP3 (P=0.044) compared with amyloid-negative individuals. Our study indicates that there is a subpopulation among healthy older individuals who have amyloid pathology along with signs of ongoing neuronal and synaptic degeneration, as well as tangle pathology. Previous studies have demonstrated that increase in CSF tau and p-tau is a specific sign of AD progression that occurs downstream of the deposition of Aβ. On the basis of this, our data suggest that these subjects are at risk for developing AD. We also confirm the association between APOE ɛ4 and amyloid pathology in healthy older individuals

    New interactions: past and future experiments

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    In this talk I will review the present status and future perspectives of some popular extensions of the conventional three-neutrino oscillation scenario, from a purely phenomenological point of view. For concreteness I will focus only on three specific scenarios: non-standard neutrino interactions with matters, models with extra sterile neutrinos, and neutrino decay and decoherence.Comment: LaTeX file using jpconf class, 8 pages, 2 tables. Proceedings of the "XXIII International Conference on Neutrino Physics and Astrophysics" (Neutrino 08), Christchurch, New Zealand, May 25-31, 200
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