279 research outputs found
Assessment of query reweighing, by rocchio method in farsi information retrieval
Due to the lack of users knowledge of the collections used by search engines and in general retrieval systems, users can not express their information need appropriately in queries. In other words, they do not have enough experience to formulate their needs to find related documents. The idea of user’s query expansion aims to help users to improve and correct the queries. In fact, retrieval system, regarding the feedback it receives from user at the first stage, moves the query in set space to more related documents. Different approaches in information retrieval systems have been used; however, there has not been any assessment of efficacy of query expansion in Farsi information retrieval systems. In this paper, expansion basic model of Rocchio, assessed as the primary model to retrieve Farsi documents, has been presented. As a matter of fact, the purpose of this study is to determine the effect of a standard and basic model on query expansion to retrieve Farsi documents, so that the researchers can compare their achievements of query expansion with the findings of this paper which showed a straightforward and positive effect on Farsi document retrieval
Tat–Dependent Translocation of an F420–Binding Protein of Mycobacterium tuberculosis
F420 is a unique cofactor present in a restricted range of microorganisms, including mycobacteria. It has been proposed that F420 has an important role in the oxidoreductive reactions of Mycobacterium tuberculosis, possibly associated with anaerobic survival and persistence. The protein encoded by Rv0132c has a predicted N–terminal signal sequence and is annotated as an F420–dependent glucose-6-phosphate dehydrogenase. Here we show that Rv0132c protein does not have the annotated activity. It does, however, co–purify with F420 during expression experiments in M. smegmatis. We also show that the Rv0132c–F420 complex is a substrate for the Tat pathway, which mediates translocation of the complex across the cytoplasmic membrane, where Rv0132c is anchored to the cell envelope. This is the first report of any F420–binding protein being a substrate for the Tat pathway and of the presence of F420 outside of the cytosol in any F420–producing microorganism. The Rv0132c protein and its Tat export sequence are essentially invariant in the Mycobacterium tuberculosis complex. Taken together, these results show that current understanding of F420 biology in mycobacteria should be expanded to include activities occurring in the extra-cytoplasmic cell envelope
SLC25A22 is a novel gene for migrating partial seizures in infancy
Objective To identify a genetic cause for migrating partial seizures in infancy (MPSI). Methods We characterized a consanguineous pedigree with MPSI and obtained DNA from affected and unaffected family members. We analyzed single nucleotide polymorphism 500K data to identify regions with evidence of linkage. We performed whole exome sequencing and analyzed homozygous variants in regions of linkage to identify a candidate gene and performed functional studies of the candidate gene SLC25A22. Results In a consanguineous pedigree with 2 individuals with MPSI, we identified 2 regions of linkage, chromosome 4p16.1-p16.3 and chromosome 11p15.4-pter. Using whole exome sequencing, we identified 8 novel homozygous variants in genes in these regions. Only 1 variant, SLC25A22 c.G328C, results in a change of a highly conserved amino acid (p.G110R) and was not present in control samples. SLC25A22 encodes a glutamate transporter with strong expression in the developing brain. We show that the specific G110R mutation, located in a transmembrane domain of the protein, disrupts mitochondrial glutamate transport. Interpretation We have shown that MPSI can be inherited and have identified a novel homozygous mutation in SLC25A22 in the affected individuals. Our data strongly suggest that SLC25A22 is responsible for MPSI, a severe condition with few known etiologies. We have demonstrated that a combination of linkage analysis and whole exome sequencing can be used for disease gene discovery. Finally, as SLC25A22 had been implicated in the distinct syndrome of neonatal epilepsy with suppression bursts on electroencephalogram, we have expanded the phenotypic spectrum associated with SLC25A22. Ann Neurol 2013;74:873-882 © 2013 American Neurological Association
F420H2-Dependent Degradation of Aflatoxin and other Furanocoumarins Is Widespread throughout the Actinomycetales
Two classes of F420-dependent reductases (FDR-A and FDR-B) that can reduce aflatoxins and thereby degrade them have previously been isolated from Mycobacterium smegmatis. One class, the FDR-A enzymes, has up to 100 times more activity than the other. F420 is a cofactor with a low reduction potential that is largely confined to the Actinomycetales and some Archaea and Proteobacteria. We have heterologously expressed ten FDR-A enzymes from diverse Actinomycetales, finding that nine can also use F420H2 to reduce aflatoxin. Thus FDR-As may be responsible for the previously observed degradation of aflatoxin in other Actinomycetales. The one FDR-A enzyme that we found not to reduce aflatoxin belonged to a distinct clade (herein denoted FDR-AA), and our subsequent expression and analysis of seven other FDR-AAs from M. smegmatis found that none could reduce aflatoxin. Certain FDR-A and FDR-B enzymes that could reduce aflatoxin also showed activity with coumarin and three furanocoumarins (angelicin, 8-methoxysporalen and imperatorin), but none of the FDR-AAs tested showed any of these activities. The shared feature of the compounds that were substrates was an α,β-unsaturated lactone moiety. This moiety occurs in a wide variety of otherwise recalcitrant xenobiotics and antibiotics, so the FDR-As and FDR-Bs may have evolved to harness the reducing power of F420 to metabolise such compounds. Mass spectrometry on the products of the FDR-catalyzed reduction of coumarin and the other furanocoumarins shows their spontaneous hydrolysis to multiple products
Metabolic Engineering of Cofactor F420 Production in Mycobacterium smegmatis
Cofactor F420 is a unique electron carrier in a number of microorganisms including Archaea and Mycobacteria. It has been shown that F420 has a direct and important role in archaeal energy metabolism whereas the role of F420 in mycobacterial metabolism has only begun to be uncovered in the last few years. It has been suggested that cofactor F420 has a role in the pathogenesis of M. tuberculosis, the causative agent of tuberculosis. In the absence of a commercial source for F420, M. smegmatis has previously been used to provide this cofactor for studies of the F420-dependent proteins from mycobacterial species. Three proteins have been shown to be involved in the F420 biosynthesis in Mycobacteria and three other proteins have been demonstrated to be involved in F420 metabolism. Here we report the over-expression of all of these proteins in M. smegmatis and testing of their importance for F420 production. The results indicate that co–expression of the F420 biosynthetic proteins can give rise to a much higher F420 production level. This was achieved by designing and preparing a new T7 promoter–based co-expression shuttle vector. A combination of co–expression of the F420 biosynthetic proteins and fine-tuning of the culture media has enabled us to achieve F420 production levels of up to 10 times higher compared with the wild type M. smegmatis strain. The high levels of the F420 produced in this study provide a suitable source of this cofactor for studies of F420-dependent proteins from other microorganisms and for possible biotechnological applications
Epidemiology of nausea and vomiting of pregnancy: prevalence, severity, determinants, and the importance of race/ethnicity
<p>Abstract</p> <p>Background</p> <p>Studies that contributed to the epidemiology of nausea and vomiting of pregnancy have reported conflicting findings, and often failed to account for all possible co-variables necessary to evaluate the multidimensional associations. The objectives of this study were to: 1) Estimate the prevalence and the severity of nausea and vomiting of pregnancy during the 1<sup>st </sup>and the 2<sup>nd </sup>trimester of pregnancy, and 2) Identify determinants of presence and severity of nausea and vomiting of pregnancy during the 1<sup>st </sup>and 2<sup>nd </sup>trimesters separately, with a special emphasis on the impact of race/ethnicity.</p> <p>Methods</p> <p>A prospective study including pregnant women attending the Centre Hospitalier Universitaire (CHU) Sainte-Justine or René-Laennec clinics for their prenatal care was conducted from 2004 to 2006. Women were eligible if they were ≥ 18 years of age, and ≤ 16 weeks of gestation. Women were asked to fill out a 1<sup>st </sup>trimester self-administered questionnaire and were interviewed over the telephone during their 2<sup>nd </sup>trimester of pregnancy. Presence of nausea and vomiting of pregnancy was based on the reporting of pregnant women (yes/no); severity of symptoms was measured by the validated modified-PUQE index.</p> <p>Results</p> <p>Of the 367 women included in the study, 81.2% were Caucasians, 10.1% Blacks, 4.6% Hispanics, and 4.1% Asians. Multivariate analyses showed that race/ethnicity was significantly associated with a decreased likelihood of reporting nausea and vomiting of pregnancy (Asians vs. Caucasians OR: 0.13; 95%CI 0.02–0.73; and Blacks vs. Caucasians OR: 0.29; 95%CI 0.09–0.99).</p> <p>Conclusion</p> <p>Our study showed that race/ethnicity was associated with the reporting of nausea and vomiting of pregnancy in the 1<sup>st </sup>trimester of pregnancy.</p
Intelligent negotiation model for ubiquitous group decision scenarios
Supporting group decision-making in ubiquitous contexts is a complex task that must deal with a large amount of
factors to succeed. Here we propose an approach for an intelligent negotiation model to support the group decision-making process
specially designed for ubiquitous contexts. Our approach can be used by researchers that intend to include arguments, complex
algorithms and agents' modelling in a negotiation model. It uses a social networking logic due to the type of communication
employed by the agents and it intends to support the ubiquitous group decision-making process in a similar way to the real process,
which simultaneously preserves the amount and quality of intelligence generated in face-to-face meetings. We propose a new look
into this problematic by considering and defining strategies to deal with important points such as the type of attributes in the multicriteria
problems, agents' reasoning and intelligent dialogues.This work has been
supported by COMPETE Programme (operational
programme for competitiveness) within project
POCI-01-0145-FEDER-007043, by National Funds
through the FCT – Fundação para a Ciência e a
Tecnologia (Portuguese Foundation for Science and
Technology) within the Projects
UID/CEC/00319/2013, UID/EEA/00760/2013, and
the João Carneiro PhD grant with the reference
SFRH/BD/89697/2012 and by Project MANTIS -
Cyber Physical System Based Proactive Collaborative
Maintenance (ECSEL JU Grant nr. 662189).info:eu-repo/semantics/publishedVersio
Roadmap on photonic metasurfaces
Funding: C.R. and U.L. acknowledge support through the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy via the Excellence Cluster 3D Matter Made to Order (EXC-2082/1, Grant No. 390761711). A.B.E. acknowledges support through the Cluster of Excellence PhoenixD (EXC 2122, Project ID No. 390833453). I.F.-C. and C.R. acknowledge support through the CRC Waves: Analysis and Numerics (SFB 1173, Grant No. 258734477. K.A. acknowledges funding from the Swiss National Science Foundation (Project No. PZ00P2_193221).Here we present a roadmap on Photonic metasurfaces. This document consists of a number of perspective articles on different applications, challenge areas or technologies underlying photonic metasurfaces. Each perspective will introduce the topic, present a state of the art as well as give an insight into the future direction of the subfield.Peer reviewe
Global, regional, and national burden of meningitis and its aetiologies, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019
Background: Although meningitis is largely preventable, it still causes hundreds of thousands of deaths globally each year. WHO set ambitious goals to reduce meningitis cases by 2030, and assessing trends in the global meningitis burden can help track progress and identify gaps in achieving these goals. Using data from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019, we aimed to assess incident cases and deaths due to acute infectious meningitis by aetiology and age from 1990 to 2019, for 204 countries and territories. Methods: We modelled meningitis mortality using vital registration, verbal autopsy, sample-based vital registration, and mortality surveillance data. Meningitis morbidity was modelled with a Bayesian compartmental model, using data from the published literature identified by a systematic review, as well as surveillance data, inpatient hospital admissions, health insurance claims, and cause-specific meningitis mortality estimates. For aetiology estimation, data from multiple causes of death, vital registration, hospital discharge, microbial laboratory, and literature studies were analysed by use of a network analysis model to estimate the proportion of meningitis deaths and cases attributable to the following aetiologies: Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae, group B Streptococcus, Escherichia coli, Klebsiella pneumoniae, Listeria monocytogenes, Staphylococcus aureus, viruses, and a residual other pathogen category. Findings: In 2019, there were an estimated 236 000 deaths (95% uncertainty interval [UI] 204 000–277 000) and 2·51 million (2·11–2·99) incident cases due to meningitis globally. The burden was greatest in children younger than 5 years, with 112 000 deaths (87 400–145 000) and 1·28 million incident cases (0·947–1·71) in 2019. Age-standardised mortality rates decreased from 7·5 (6·6–8·4) per 100 000 population in 1990 to 3·3 (2·8–3·9) per 100 000 population in 2019. The highest proportion of total all-age meningitis deaths in 2019 was attributable to S pneumoniae (18·1% [17·1–19·2]), followed by N meningitidis (13·6% [12·7–14·4]) and K pneumoniae (12·2% [10·2–14·3]). Between 1990 and 2019, H influenzae showed the largest reduction in the number of deaths among children younger than 5 years (76·5% [69·5–81·8]), followed by N meningitidis (72·3% [64·4–78·5]) and viruses (58·2% [47·1–67·3]). Interpretation: Substantial progress has been made in reducing meningitis mortality over the past three decades. However, more meningitis-related deaths might be prevented by quickly scaling up immunisation and expanding access to health services. Further reduction in the global meningitis burden should be possible through low-cost multivalent vaccines, increased access to accurate and rapid diagnostic assays, enhanced surveillance, and early treatment. Funding: Bill & Melinda Gates Foundation
The global burden of cancer attributable to risk factors, 2010-19: a systematic analysis for the Global Burden of Disease Study 2019
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