1,150 research outputs found

    Lifting Grobner bases from the exterior algebra

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    In the article "Non-commutative Grobner bases for commutative algebras", Eisenbud-Peeva-Sturmfels proved a number of results regarding Grobner bases and initial ideals of those ideals in the free associative algebra which contain the commutator ideal. We prove similar results for ideals which contains the anti-commutator ideal (the defining ideal of the exterior algebra). We define one notion of generic initial ideals in the free assoicative algebra, and show that gin's of ideals containing the commutator ideal, or the anti-commutator ideal, are finitely generated.Comment: 6 pages, LaTeX2

    Chemical exchange saturation transfer MRI shows low cerebral 2-deoxy-D-glucose uptake in a model of Alzheimer's Disease

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    Glucose is the central nervous system's only energy source. Imaging techniques capable to detect pathological alterations of the brain metabolism are useful in different diagnostic processes. Such techniques are also beneficial for assessing the evaluation efficacy of therapies in pre-clinical and clinical stages of diseases. Chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) is a possible alternative to positron emission tomography (PET) imaging that has been widely explored in cancer research in humans and animal models. We propose that pathological alterations in brain 2-deoxy-D-glucose (2DG) uptake, typical of neurodegenerative diseases, can be detected with CEST MRI. Transgenic mice overexpressing a mutated form of amyloid precusrsor protein (APP23), a model of Alzheimer's disease, analyzed with CEST MRI showed a clear reduction of 2DG uptake in different brain regions. This was reminiscent of the cerebral condition observed in Alzheimer's patients. The results indicate the feasibility of CEST for analyzing the brain metabolic state, with better image resolution than PET in experimental models

    The effects of matter density uncertainties on neutrino oscillations in the Earth

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    We compare three different methods to evaluate uncertainties in the Earth's matter density profile, which are relevant to long baseline experiments, such as neutrino factories.Comment: 3 pages, 1 figure. Talk given at the NuFact'02 Workshop, London, 1-6 July, 200

    Magnetic moments of the 3/2 resonances and their quark spin structure

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    We discuss magnetic moments of the J=3/2J=3/2 baryons based on an earlier model for the baryon magnetic moments, allowing for flavor symmetry breaking in the quark magnetic moments as well as a general quark spin structure. From our earlier analysis of the nucleon-hyperon magnetic moments and the measured values of the magnetic moments of Δ++\Delta^{++} and Ω\Omega^{-} we predict the other magnetic moments and deduce the spin structure of the resonance particles. We find from experiment that the total spin polarization of the decuplet baryons, ΔΣ(3/2)\Delta\Sigma(3/2), is considerably smaller than the non-relativistic quark model value of 3, although the data is still not good enough to give a precise determination.Comment: 13 pages, REVTeX, 2 figures, minor clarifying change

    Magnetic Resonance Imaging Findings in Finnish Spitz Dogs with Focal Epilepsy

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    Eleven Finnish Spitz dogs with focal seizures and 3 healthy controls were evaluated. General clinical and neurological examinations, blood examination, urinalysis, cerebrospinal fluid examination, electroencephalography (EEG), and magnetic resonance imaging (MRI) of the brain were performed on all dogs. On EEG examination, focal epileptic activity was found in 7 of 11 dogs (64%), and generalized epileptic activity was observed in 4 of 11 dogs (36%). MRI (performed with 1.5 T equipment) detected changes in 1 epileptic dog. Mild contrast enhancement after gadolinium injection was identified in this dog's right parietal cortex. However, no such changes were observed in repeated magnetic resonance images. Special emphasis was given to seizure history to determine any correlations between seizure intervals and MRI findings. Our results indicate that Finnish Spitz dogs with focal seizures suffer from focal idiopathic epilepsy and have nondetectable findings on MRI or pathology. MRI showed poor sensitivity in detecting epileptogenic areas in our patients with focal seizures. Reversible MRI changes in 1 dog could have been caused by seizures

    Associations of Fully Automated CSF and Novel Plasma Biomarkers With Alzheimer Disease Neuropathology at Autopsy

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    OBJECTIVE: To study cerebrospinal fluid (CSF) biomarkers of Alzheimer's disease (AD) analyzed by fully automated Elecsys immunoassays in comparison to neuropathologic gold standards, and compare their accuracy to plasma phosphorylated tau (p-tau181) measured using a novel Simoa method. METHODS: We studied ante-mortem Elecsys-derived CSF biomarkers in 45 individuals who underwent standardized post-mortem assessments of AD and non-AD neuropathologic changes at autopsy. In a subset of 26 participants, we also analysed ante-mortem levels of plasma p-tau181 and neurofilament light (NfL). Reference biomarker values were obtained from 146 amyloid-PET-negative healthy controls (HC). RESULTS: All CSF biomarkers clearly distinguished pathology-confirmed AD dementia (N=27) from HC (AUCs=0.86-1.00). CSF total-tau (t-tau), p-tau181, and their ratios with Aβ1-42, also accurately distinguished pathology-confirmed AD from non-AD dementia (N=8; AUCs=0.94-0.97). In pathology-specific analyses, intermediate-to-high Thal amyloid phases were best detected by CSF Aβ1-42 (AUC[95% CI]=0.91[0.81-1]), while intermediate-to-high CERAD neuritic plaques and Braak tau stages were best detected by CSF p-tau181 (AUC=0.89[0.79-0.99] and 0.88[0.77-0.99], respectively). Optimal Elecsys biomarker cut-offs were derived at 1097/229/19 pg/ml for Aβ1-42, t-tau, and p-tau181. In the plasma subsample, both plasma p-tau181 (AUC=0.91[0.86-0.96]) and NfL (AUC=0.93[0.87-0.99]) accurately distinguished pathology-confirmed AD (N=14) from HC. However, only p-tau181 distinguished AD from non-AD dementia cases (N=4; AUC=0.96[0.88-1.00]), and showed a similar, though weaker, pathologic specificity for neuritic plaques (AUC=0.75[0.52-0.98]) and Braak stage (AUC=0.71[0.44-0.98]) as CSF p-tau181. CONCLUSIONS: Elecsys-derived CSF biomarkers detect AD neuropathologic changes with very high discriminative accuracy in-vivo. Preliminary findings support the use of plasma p-tau181 as an easily accessible and scalable biomarker of AD pathology. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that fully-automated CSF t-tau and p-tau181measurements discriminate between autopsy-confirmed Alzheimer's disease and other dementias

    GRADE equity guidelines 4: guidance on how to assess and address health equity within the evidence to decision process

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    Objective: The aim of this paper is to provide detailed guidance on how to incorporate health equity within the GRADE (Grading Recommendations Assessment and Development Evidence) evidence to decision process. Study design and setting: We developed this guidance based on the GRADE evidence to decision (EtD) framework, iteratively reviewing and modifying draft documents, in person discussion of project group members and input from other GRADE members. Results: Considering the impact on health equity may be required, both in general guidelines, and guidelines that focus on disadvantaged populations. We suggest two approaches to incorporate equity considerations: 1) assessing the potential impact of interventions on equity and; 2) incorporating equity considerations when judging or weighing each of the evidence to decision criteria. We provide guidance and include illustrative examples. Conclusion: Guideline panels should consider the impact of recommendations on health equity with attention to remote and underserviced settings and disadvantaged populations. Guideline panels may wish to incorporate equity judgments across the evidence to decision framework

    Octet Baryon Magnetic Moments in the Chiral Quark Model with Configuration Mixing

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    The Coleman-Glashow sum-rule for magnetic moments is always fulfilled in the chiral quark model, independently of SU(3) symmetry breaking. This is due to the structure of the wave functions, coming from the non-relativistic quark model. Experimentally, the Coleman-Glashow sum-rule is violated by about ten standard deviations. To overcome this problem, two models of wave functions with configuration mixing are studied. One of these models violates the Coleman-Glashow sum-rule to the right degree and also reproduces the octet baryon magnetic moments rather accurately.Comment: 22 pages, RevTe
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