Question Answering (QA) systems are often built modularly, with a text retrieval component feeding forward into an answer extraction component. Conventional wisdom suggests that, the higher the quality of the retrieval results used as input to the answer extraction module, the better the extracted answers, and hence system accuracy, will be. This turns out to be a poor assumption, because text ...

Alzheimer's disease (AD) is one of the major causes of dementia. The pathogenesis of the disease is not entirely understood, but the amyloid β peptide (Aβ) and the formation of senile plaques seem to play pivotal roles. Oligomerization of the Aβ is thought to trigger a cascade of events, including oxidative stress, glutamate excitotoxicity and inflammation. The kynurenine (KYN) pathway is the m...

BACKGROUND Quinolinic acid (QA) is a neurotoxin and has been shown to be present at high levels in the central nervous system of patients with certain diseases, such as AIDS and meningitis. The enzyme quinolinic acid phosphoribosyltransferase (QAPRTase) provides the only route for QA metabolism and is also an essential step in de novo NAD biosynthesis. QAPRTase catalyzes the synthesis of nicoti...

Rat striata were exposed to 15 mM quinolinic acid (QUIN), or QUIN plus the nitric oxide synthase inhibitors S-methyl-L-thiocitrulline dihydrochloride (L-MIN) or 7-nitroindazole monosodium salt (7-NINA) for 21 days. Co-administration of 100 microM or 1 mM L-MIN with QUIN significantly reduced lesion volume compared to QUIN alone. Co-administration of 1 microM or 10 microM L-MIN with QUIN had no ...

In order to investigate the role of the dorsomedial and dorsolateral caudate-putamen (CPu) in movement initiation of rats, we examined the effects of quinolinic acid lesions (30 nmol in 1 microliter) in these striatal subregions in a simple reaction time task. Results show that lesions of the dorsomedial, but not of the dorsolateral CPu increased reaction times. These findings provide further e...

A retrospective study of 261 Vietnamese adults with severe malaria was conducted to determine the relationship between cerebrospinal fluid (CSF) levels of metabolites of the kynurenine pathway, the incidence of neurologic complications, and the disease outcome. Three metabolites were measured: the excitotoxin quinolinic acid (QA); the protective receptor antagonist kynurenic acid (KA); and the ...

Nicotinamide adenine dinucleotide (NAD) is a ubiquitous coenzyme in oxidation-reduction reactions. Recent animal and fungal studies show that it also plays important roles in transcriptional regulation, longevity, and age-associated diseases. NAD is synthesized de novo from aspartic acid in E. coli or from tryptophan in animals, by way of quinolinic acid. Although the number of biochemical stud...

Department of Biology, University of Turku, SF-20500 Turku, Finland (P.M., E.T., T.T.); Section of Bioénergetique, Département de Biologie Cellulaire et Moléculaire, lnstitut National de Ia Recherche Agronomique/Comissariat de I’Energie Atomique-Saclay, 91 190 Gif sur Yvette, France (T.M., I.-M.D.); Department of Plant Biology, University of Illinois, Urbana, lllinois 61 801 (G.); and Photoregu...

The series system means that both components must work for systems success. From probability concepts (independent events), the reliability (system success) of the above system (RAB) is given as: RAB = RA RB and the system unreliability (system failure), designated as Q is given as: QAB = 1 RAB = 1 RA RB considering that, Q + R = 1 or R = 1 Q, therefore, QAB = 1 (1 QA) (1 QB) = QA + QB QA QB Fo...

We generalize Berreman's model to the case qA > or = 1 , where q is the wave vector of the surface structure and A its amplitude, to describe the alignment induced by a solid surface on a nematic liquid crystal. We show that, by taking into account correctly the elastic contribution to the surface energy connected with the surface topography, the effective surface energy is smaller than the one...