2,181 research outputs found

    Concurrent Lexicalized Dependency Parsing: A Behavioral View on ParseTalk Events

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    The behavioral specification of an object-oriented grammar model is considered. The model is based on full lexicalization, head-orientation via valency constraints and dependency relations, inheritance as a means for non-redundant lexicon specification, and concurrency of computation. The computation model relies upon the actor paradigm, with concurrency entering through asynchronous message passing between actors. In particular, we here elaborate on principles of how the global behavior of a lexically distributed grammar and its corresponding parser can be specified in terms of event type networks and event networks, resp.Comment: 68kB, 5pages Postscrip

    Concurrent Lexicalized Dependency Parsing: The ParseTalk Model

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    A grammar model for concurrent, object-oriented natural language parsing is introduced. Complete lexical distribution of grammatical knowledge is achieved building upon the head-oriented notions of valency and dependency, while inheritance mechanisms are used to capture lexical generalizations. The underlying concurrent computation model relies upon the actor paradigm. We consider message passing protocols for establishing dependency relations and ambiguity handling.Comment: 90kB, 7pages Postscrip

    Message-Passing Protocols for Real-World Parsing -- An Object-Oriented Model and its Preliminary Evaluation

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    We argue for a performance-based design of natural language grammars and their associated parsers in order to meet the constraints imposed by real-world NLP. Our approach incorporates declarative and procedural knowledge about language and language use within an object-oriented specification framework. We discuss several message-passing protocols for parsing and provide reasons for sacrificing completeness of the parse in favor of efficiency based on a preliminary empirical evaluation.Comment: 12 pages, uses epsfig.st

    Interdépendance du potentiel d'exploitation et la structure d'habitat dans la région de l'Atakora

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    Le dĂ©partement de l’Atakora est une rĂ©gion trĂšs contrastĂ©e et jusqu’à prĂ©sent trĂšs peu explorĂ©e. Son Ă©lĂ©ment le plus saillant est la ChaĂźne de l’Atakora, une des rares Ă©lĂ©vations montagneuses de cette partie de l’Afrique occidentale. Le haut-plateau de l’Atakora est caractĂ©risĂ© par une densitĂ© de la population relativement basse, comparĂ©e au reste de la rĂ©gion, et une vĂ©gĂ©tation variĂ©e, qui est jusqu’à prĂ©sent extrĂȘmement mal connu. Il contraste fortement avec son piĂ©mont Ă  l’ouest de la chaĂźne qui est trĂšs densĂ©ment peuplĂ© et exploitĂ© de maniĂšre intensive. Notre recherche a Ă©tĂ© consacrĂ©e Ă  la question de savoir si ce sont des facteurs dĂ©pendant du gĂ©opotentiel ou plutĂŽt des donnĂ©es socio-Ă©conomiques qui sont responsables pour la disparitĂ© actuelle de ce paysage. Partant de l’hypothĂšse que non seulement les conditions socio-Ă©conomiques mais aussi les conditions naturelles sont beaucoup plus favorables dans le piĂ©mont que sur le plateau, nous avons - par une approche interdisciplinaire - effectuĂ© une analyse et une Ă©valuation de ces facteurs. Des mĂ©thodes de la tĂ©lĂ©dĂ©tection, de la pĂ©dologie, de la botanique et de la gĂ©ographie agraire ont Ă©tĂ© employĂ©es

    Reaction optimization of a Suzuki‐Miyaura cross‐coupling using design of experiments

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    The combination of lab automation and design of experiments for the execution of screening experiments increases productivity and reduces error-prone manual work. A self-developed software tool allows for creating fractional-factorial experimental design (FFED). Application of FFED on the screening of a Suzuki-Miyaura cross-coupling leads to a 93 % reduced design compared to full-factorial design. The resulting regression model qualitatively shows the positive effect of educt concentrations, time, and temperature and reveals the decrease in conversion at high base concentrations

    Highly conserved serine residue 40 in HIV-1 p6 regulates capsid processing and virus core assembly

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    Background: The HIV-1 p6 Gag protein regulates the final abscission step of nascent virions from the cell membrane by the action of two late assembly (L-) domains. Although p6 is located within one of the most polymorphic regions of the HIV-1 gag gene, the 52 amino acid peptide binds at least to two cellular budding factors (Tsg101 and ALIX), is a substrate for phosphorylation, ubiquitination, and sumoylation, and mediates the incorporation of the HIV-1 accessory protein Vpr into viral particles. As expected, known functional domains mostly overlap with several conserved residues in p6. In this study, we investigated the importance of the highly conserved serine residue at position 40, which until now has not been assigned to any known function of p6. Results: Consistently with previous data, we found that mutation of Ser-40 has no effect on ALIX mediated rescue of HIV-1 L-domain mutants. However, the only feasible S40F mutation that preserves the overlapping pol open reading frame (ORF) reduces virus replication in T-cell lines and in human lymphocyte tissue cultivated ex vivo. Most intriguingly, L-domain mediated virus release is not dependent on the integrity of Ser-40. However, the S40F mutation significantly reduces the specific infectivity of released virions. Further, it was observed that mutation of Ser-40 selectively interferes with the cleavage between capsid (CA) and the spacer peptide SP1 in Gag, without affecting cleavage of other Gag products. This deficiency in processing of CA, in consequence, led to an irregular morphology of the virus core and the formation of an electron dense extra core structure. Moreover, the defects induced by the S40F mutation in p6 can be rescued by the A1V mutation in SP1 that generally enhances processing of the CA-SP1 cleavage site. Conclusions: Overall, these data support a so far unrecognized function of p6 mediated by Ser-40 that occurs independently of the L-domain function, but selectively affects CA maturation and virus core formation, and consequently the infectivity of released virions

    Multidisciplinary Late Effects Clinics for Childhood Cancer Survivors in Germany - a Two-Center Study

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    Background: Childhood cancer survivors are at risk for therapy-related sequelae and, therefore, require long-term follow-up. At 2 university hospitals in Germany collaborative multidisciplinary late effects clinics were installed to provide specialized care and to evaluate the current health status of these patients in a clinical setting. Patients andMethods: Every patient who visited the late effects clinics at the university hospital in LĂŒbeck and Erlangen over a period of 3 years and met the inclusion criteria was included in the study. Patients' characteristics as well as cancer diagnosis, treatment related factors and the prevalence of chronic health conditions were assessed. Results: 220 patients attended the late effects clinics during the observation period. The median follow-up period was 16 years (range 5-45 years). In total over 64% of the patients were affected by at least 1 chronic health condition, including endocrine disruptions in 19.1% of the patients. Moreover, secondary neoplasms occurred in 9.1% of the study participants. Conclusion: German childhood cancer survivors are affected by multiple therapy-related sequelae. A comprehensive network of late effects clinics should be established to ensure specialized and risk-adapted care for every childhood cancer survivor in Germany

    The usefulness of C-reactive protein in predicting malaria parasitemia in a sub-Saharan African region.

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    BACKGROUND: Malaria remains a leading cause of childhood mortality in sub-Saharan Africa. Identifying patients who are at risk for severe manifestations at presentation still remains challenging. This study examines whether a semi-quantitative test on C-Reactive Protein (CRP) could be useful for rapidly predicting the presence or absence of malarial parasitemia in febrile children. METHOD: Data were collected from children with fever or a history of fever at the Agogo Presbyterian Hospital in the Ashanti Region of Ghana. Haematological measurements, microscopic detection of plasmodium species and semi-quantitative CRP measurements with a membrane-based immunoassay for whole blood were performed. CRP was classified as positive when the measured level was ≄ 10 mg/l. RESULTS: During 548 visits, thick blood film results could be obtained from 541 patients, 270 (49.3%) yielded parasitemia with Plasmodium spp. Whereas malaria parasites were detected in only a few patients (7.1%) with normal CRP levels (< 10mg/l), more than a half of patients with an increased CRP concentration (≄ 10 mg/l) were parasite positive (OR 14.5 [CI 4.4-47.6], p<0.001). Patients with increased CRP levels had more than an eight-fold likelihood for parasitemia after correction for other parameters (adjusted OR 8.7 [CI 2.5-30.5], p<0.001). Sensitivity, specificity as well as positive predictive and negative predictive values of CRP for malaria were 99.3% (CI 96.2%-100%), 9.2% (CI 6.4%-12.8%), 31.7% (CI 27.4%-36.1%) and 97.0% (CI 84.2%-99.9%), respectively. CONCLUSION: The semi-quantitative method of measuring CRP is cheap, rapid and easy to perform but not useful in predicting parasitemia and malaria. However, due to its high negative predictive value, it could have a role in identifying those patients unlikely to be presenting with clinical malaria

    Sinus lifting before Le Fort I maxillary osteotomy: a suitable method for oral rehabilitation of edentulous patients with skelettal class-III conditions: review of the literature and report of a case

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    BACKGROUND: Functional rehabilitation of patients afflicted with severe mandibular and maxillary alveolar atrophy might be challenging especially in malformed patients. METHODS: Treatment planning using sinus lifting and implant placement before Le Fort I maxillary osteotomy in a patient with severe mandibular and posterior maxillary alveolar atrophy and skelettal class-III conditions due to cleft palate are described. RESULTS: A full functional and esthetic rehabilitation of the patient was achieved by a stepwise surgical approach performed through sinus lifting as the primary approach followed by implant placement and subsequent Le Fort I maxillary osteotomy to correct the maxillo-mandibular relation. CONCLUSION: Stabilisation of the maxillary complex by a sinus lifting procedure in combination with computer aided implant placement as preorthodontic planning procedure before Le Fort I maxillary osteotomy seems to be suitable in order to allow ideal oral rehabilitation especially in malformed patients

    16S rRNA Gene Sequence-Based Identification of Bacteria in Automatically Incubated Blood Culture Materials from Tropical Sub-Saharan Africa.

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    BACKGROUND: The quality of microbiological diagnostic procedures depends on pre-analytic conditions. We compared the results of 16S rRNA gene PCR and sequencing from automatically incubated blood culture materials from tropical Ghana with the results of cultural growth after automated incubation. METHODS: Real-time 16S rRNA gene PCR and subsequent sequencing were applied to 1500 retained blood culture samples of Ghanaian patients admitted to a hospital with an unknown febrile illness after enrichment by automated culture. RESULTS: Out of all 1500 samples, 191 were culture-positive and 98 isolates were considered etiologically relevant. Out of the 191 culture-positive samples, 16S rRNA gene PCR and sequencing led to concordant results in 65 cases at species level and an additional 62 cases at genus level. PCR was positive in further 360 out of 1309 culture-negative samples, sequencing results of which suggested etiologically relevant pathogen detections in 62 instances, detections of uncertain relevance in 50 instances, and DNA contamination due to sample preparation in 248 instances. In two instances, PCR failed to detect contaminants from the skin flora that were culturally detectable. Pre-analytical errors caused many Enterobacteriaceae to be missed by culture. CONCLUSIONS: Potentially correctable pre-analytical conditions and not the fastidious nature of the bacteria caused most of the discrepancies. Although 16S rRNA gene PCR and sequencing in addition to culture led to an increase in detections of presumably etiologically relevant blood culture pathogens, the application of this procedure to samples from the tropics was hampered by a high contamination rate. Careful interpretation of diagnostic results is required
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