168 research outputs found
Neutrino Oscillations in Deconstructed Dimensions
We present a model for neutrino oscillations in the presence of a
deconstructed non-gravitational large extra dimension compactified on the
boundary of a two-dimensional disk. In the deconstructed phase, sub-mm lattice
spacings are generated from the hierarchy of energy scales between 1 TeV and
the usual B-L breaking scale 10^{15} GeV. Here, short distance cutoffs down to
1 eV can be motivated by the strong coupling behavior of gravity in local
discrete extra dimensions. This could make it possible to probe the
discretization of extra dimensions and non-trivial field configurations in
theory spaces which have only a few sites, i.e., for coarse latticizations.
Thus, the model has relevance to present and future precision neutrino
oscillation experiments.Comment: 38 pages, 11 figures, typos correcte
Tomography of the Earth's Core Using Supernova Neutrinos
We investigate the possibility to use the neutrinos coming from a future
galactic supernova explosion to perform neutrino oscillation tomography of the
Earth's core. We propose to use existing or planned detectors, resulting in an
additional payoff. Provided that all of the discussed uncertainties can be
reduced as expected, we find that the average matter densities of the Earth's
inner and outer cores could be measured with a precision competitive with
geophysics. However, since seismic waves are more sensitive to matter density
jumps than average matter densities, neutrino physics would give partly
complementary information.Comment: 17 pages, 6 figures, LaTeX. Final version to be published in
Astropart. Phy
Treatment with Unlabeled mAb BR96 After Radioimmunotherapy with (177)Lu-DOTA-BR96 in a Syngeneic Rat Colon Carcinoma Model.
Metastatic disease after successful treatment of the primary tumor continues to be a therapeutic challenge. Enhancement of therapeutic effects by the administration of unlabeled monoclonal antibodies (mAbs) after radioimmunotherapy (RIT) may provide a means of preventing or delaying the development of metastatic disease. In the present study, Brown Norway rats with syngeneic grafted colon carcinomas were administered the minimal effective therapeutic dose of 400 MBq/kg lutetium-177 ((177)Lu)-DOTA-BR96. After 2 weeks, half of the animals were given 15 mg/kg unlabeled mAb BR96 as consolidation therapy. Treatment response and toxicity were monitored 100 days after the treatment with unlabeled BR96. The treatment with unlabeled mAb after RIT resulted in a complete response (CR) in 19 of 19 animals, while RIT alone resulted in a CR in 17 of 19 animals. The additional treatment did not affect the number of animals with metastatic disease or the time to clinical symptoms of metastases. RIT resulted in reversible myelotoxicity. The unlabeled mAb BR96 did not cause any additional toxicity, making it possible to repeat the consolidation therapy
Pattern of antigen expression in metastases after radioimmunotherapy of a syngeneic rat colon carcinoma utilizing the BR96 antibody.
Abstract ABSTRACT: BACKGROUND: Repeated administration of antibody-based therapies such as radioimmunotherapy depends on preserved antigen expression in tumor lesions. The purpose of this study was to evaluate whether the antigen expression in metastases observed after radioimmunotherapy differs from that of untreated primary tumors. FINDINGS: 30 of the 35 Brown Norway rats with syngeneic colon carcinoma treated with 400 MBq/kg 177Lu-DOTA-BR96 exhibited consistent complete response of the primary tumor. 13 animals developed metastases that were detected after treatment. The antigen expression was reduced in 17 of 23 metastases detected after radioimmunotherapy compared with untreated tumors. No tumors completely lacked positively stained tumor cells. CONCLUSIONS: Although it was not possible to demonstrate that the antigen reduction is triggered by the radioimmunotherapy this result stress the importance of considering the risk of reduced antigen expression in metastases after radioimmunotherapy prior to further targeted therapies
Triplet Leptogenesis in Left-Right Symmetric Seesaw Models
We discuss scalar triplet leptogenesis in a specific left-right symmetric
seesaw model. We show that the Majorana phases that are present in the model
can be effectively used to saturate the existing upper limit on the
CP-asymmetry of the triplets. We solve the relevant Boltzmann equations and
analyze the viability of triplet leptogenesis. It is known for this kind of
scenario that the efficiency of leptogenesis is maximal if there exists a
hierarchy between the branching ratios of the triplet decays into leptons and
Higgs particles. We show that triplet leptogenesis typically favors branching
ratios with not too strong hierarchies, since maximal efficiency can only be
obtained at the expense of suppressed CP-asymmetries.Comment: 16 pages, 5 figures, published versio
The Intratumoral Distribution of Radiolabeled 177Lu-BR96 Monoclonal Antibodies Changes in Relation to Tumor Histology over Time in a Syngeneic Rat Colon Carcinoma Model.
The therapeutic effect of radioimmunotherapy depends on the distribution of the absorbed dose in relation to viable cancer cells within the tumor, which in turn is a function of the activity distribution. The aim of this study was to investigate the distribution of (177)Lu-DOTA-BR96 monoclonal antibodies targeting the Lewis Y antigen over 7 d using a syngeneic rat model of colon carcinoma
Stability and leptogenesis in the left-right symmetric seesaw mechanism
We analyze the left-right symmetric type I+II seesaw mechanism, where an
eight-fold degeneracy among the mass matrices of heavy right-handed neutrinos
M_R is known to exist. Using the stability property of the solutions and their
ability to lead to successful baryogenesis via leptogenesis as additional
criteria, we discriminate among these eight solutions and partially lift their
eight-fold degeneracy. In particular, we find that viable leptogenesis is
generically possible for four out of the eight solutions.Comment: 25 pages, 11 figures, latex; minor changes, published versio
Indirect Detection of Kaluza-Klein Dark Matter from Latticized Universal Dimensions
We consider Kaluza-Klein dark matter from latticized universal dimensions. We
motivate and investigate two different lattice models, where the models differ
in the choice of boundary conditions. The models reproduce relevant features of
the continuum model for Kaluza-Klein dark matter. For the model with simple
boundary conditions, this is the case even for a model with only a few lattice
sites. We study the effects of the latticization on the differential flux of
positrons from Kaluza-Klein dark matter annihilation in the galactic halo. We
find that for different choices of the compactification radius, the
differential positron flux rapidly converges to the continuum model results as
a function of the number of lattice sites. In addition, we consider the
prospects for upcoming space-based experiments such as PAMELA and AMS-02 to
probe the latticization effect.Comment: 25 pages, 9 figures, LaTeX. Final version published in JCA
18F-AV-1451 tau PET imaging correlates strongly with tau neuropathology in MAPT mutation carriers
Tau positron emission tomography ligands provide the novel possibility to image tau pathology in vivo. However, little is known about how in vivo brain uptake of tau positron emission tomography ligands relates to tau aggregates observed post-mortem. We performed tau positron emission tomography imaging with 18F-AV-1451 in three patients harbouring a p.R406W mutation in the MAPT gene, encoding tau. This mutation results in 3- and 4-repeat tau aggregates similar to those in Alzheimer's disease, and many of the mutation carriers initially suffer from memory impairment and temporal lobe atrophy. Two patients with short disease duration and isolated memory impairment exhibited 18F-AV-1451 uptake mainly in the hippocampus and adjacent temporal lobe regions, correlating with glucose hypometabolism in corresponding regions. One patient died after 26 years of disease duration with dementia and behavioural deficits. Pre-mortem, there was 18F-AV-1451 uptake in the temporal and frontal lobes, as well as in the basal ganglia, which strongly correlated with the regional extent and amount of tau pathology in post-mortem brain sections. Amyloid-β (18F-flutemetamol) positron emission tomography scans were negative in all cases, as were stainings of brain sections for amyloid. This provides strong evidence that 18F-AV-1451 positron emission tomography can be used to accurately quantify in vivo the regional distribution of hyperphosphorylated tau protein
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