938 resultados para Classification of singularities


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Density, rheological properties, and conductivity of a homologous series of ammonium-based ionic liquids N-alkyl-triethylammonium bis{(trifluoromethyl) sulfonyl}imide were studied at atmospheric pressure as a function of alkyl chain length on the cation, as well as of the temperature from (293.15 to 363.15) K. From these investigations, the effect of the cation structure was quantified on each studied properties, which demonstrated, as expected, a decrease of the density and conductivity, a contrario of an increase of the viscosity with the alkyl chain length on the ammonium cation. Furthermore, rheological properties were measured for both pure and water-saturated ionic liquids. The studied ionic liquids were found to be Newtonian and non-Arrhenius. Additionally, the effect of water content in the studied ionic liquids on their viscosity was investigated by adding water until they were saturated at 293.15 K. By comparing the viscosity of pure ionic liquids with the data measured in water-saturated samples, it appears that the presence of water decreases dramatically the viscosity of ionic liquids by up to three times. An analysis of involved transport properties leads us to a classification of the studied ionic liquids in terms of their ionicity using the Walden plot, from which it is evident that they can be classified as "good" ionic liquids. Finally, from measured density data, different volumetric properties, that is, molar volumes and thermal expansion coefficients were determined as a function of temperature and of cationic structure. Based on these volumetric properties, an extension of Jacquemin's group contribution model has been then established and tested for alkylammonium-based ionic liquids within a relatively good uncertainty close to 0.1 %. © 2012 American Chemical Society.

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PURPOSE: To identify vision Patient-Reported Outcomes instruments relevant to glaucoma and assess their content validity.

METHODS: MEDLINE, MEDLINE in Process, EMBASE and SCOPUS (to January 2009) were systematically searched. Observational studies or randomised controlled trials, published in English, reporting use of vision instruments in glaucoma studies involving adults were included. In addition, reference lists were scanned to identify additional studies describing development and/or validation to ascertain the final version of the instruments. Instruments' content was then mapped onto a theoretical framework, the World Health Organization International Classification of Functioning, Disability and Health. Two reviewers independently evaluated studies for inclusion and quality assessed instrument content.

RESULTS: Thirty-three instruments were identified. Instruments were categorised into thirteen vision status, two vision disability, one vision satisfaction, five glaucoma status, one glaucoma medication related to health status, five glaucoma medication side effects and six glaucoma medication satisfaction measures according to each instruments' content. The National Eye Institute Visual Function Questionnaire-25, Impact of Vision Impairment and Treatment Satisfaction Survey-Intraocular Pressure had the highest number of positive ratings in the content validity assessment.

CONCLUSION: This study provides a descriptive catalogue of vision-specific PRO instruments, to inform the choice of an appropriate measure of patient-reported outcomes in a glaucoma context.

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Dioxin contamination of the food chain typically occurs when cocktails of combustion residues or polychlorinated biphenyl (PCB) containing oils become incorporated into animal feed. These highly toxic compounds are bioaccumulative with small amounts posing a major health risk. The ability to identify animal exposure to these compounds prior to their entry into the food chain may be an invaluable tool to safeguard public health. Dioxin-like compounds act by a common mode of action and this suggests that markers or patterns of response may facilitate identification of exposed animals. However, secondary co-contaminating compounds present in typical dioxin sources may affect responses to compounds. This study has investigated for the first time the potential of a metabolomics platform to distinguish between animals exposed to different sources of dioxin contamination through their diet. Sprague-Dawley rats were given feed containing dioxin-like toxins from hospital incinerator soot, a common PCB oil standard and pure 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (normalized at 0.1 µg/kg TEQ) and acquired plasma was subsequently biochemically profiled using ultra high performance liquid chromatography (UPLC) quadropole time-of-flight-mass spectrometry (QTof-MS). An OPLS-DA model was generated from acquired metabolite fingerprints and validated which allowed classification of plasma from individual animals into the four dietary exposure study groups with a level of accuracy of 97-100%. A set of 24 ions of importance to the prediction model, and which had levels significantly altered between feeding groups, were positively identified as deriving from eight identifiable metabolites including lysophosphatidylcholine (16:0) and tyrosine. This study demonstrates the enormous potential of metabolomic-based profiling to provide a powerful and reliable tool for the detection of dioxin exposure in food-producing animals.

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Immunohistochemistry (IHC) plays a central role in the histopathological classification of diseases, including cancer. More recently, the importance of immunohistochemical staining is increasing. IHC usage in diagnostics is invaluable; however, the genetic and therapeutic significance of biomarker immunostaining has become equally relevant.

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Objective: To investigate the effect of socioeconomic deprivation on cornea graft survival in the United Kingdom.

Design: Retrospective cohort study.

Participants: All the recipients (n = 13?644) undergoing their first penetrating keratoplasty (PK) registered on the United Kingdom Transplant Registry between April 1999 and March 2011 were included.

Methods: Data of patients' demographic details, indications, graft size, corneal vascularization, surgical complication, rejection episodes, and postoperative medication were collected at the time of surgery and 1, 2, and 5 years postoperatively. Patients with endophthalmitis were excluded from the study. Patients' home postcodes were used to determine the socioeconomic status using a well-validated deprivation index in the United Kingdom: A Classification of Residential Neighborhoods (ACORN). Kaplan–Meier survival and Cox proportional hazards regression were used to evaluate the influence of ACORN categories on 5-year graft survival, and the Bonferroni method was used to adjust for multiple comparisons.

Main Outcome Measures: Patients' socioeconomic deprivation status and corneal graft failure.

Results: A total of 13?644 patients received their first PK during the study periods. A total of 1685 patients (13.36%) were lost to follow-up, leaving 11?821 patients (86.64%) for analysis. A total of 138 of the 11?821 patients (1.17%) developed endophthalmitis. The risk of graft failure within 5 years for the patients classified as hard-pressed was 1.3 times that of the least deprived (hazard ratio, 1.3; 95% confidence interval, 1.1–1.5; P = 0.003) after adjusting for confounding factors and indications. There were no statistically significant differences between the causes of graft failure and the level of deprivation (P = 0.14).

Conclusions: Patients classified as hard-pressed had an increased risk of graft failure within 5 years compared with the least deprived patients.

Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article

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Weathering-rind thicknesses on pebble-and cobble-size sediment have been used for the past half-century, at least, as an age indicator of postdepositional time following a geologic event. In mountainous terrain, rind thickness is taken as a measurement of weathering over time frames of 0.5 m.yr.; variable thicknesses are used to discriminate relative ages of glacial deposits. The effects of chemical and physical weathering that together produce rinds are only rarely considered, and most research objectives have centered on lichen alteration of clast surfaces. Recent microscopic analyses of weathering rinds on volcanic clasts of similar to 70.0-ka to similar to 2.0-m.yr. age produced new data on weathering products as well as unexpected incorporated biotic materials undergoing diagenesis. The question as to how much physical/mineral/chemical/ biotic paleoenvironmental data might be archived in rinds is discussed. The character and classification of organic materials undergoing diagenesis are also discussed.

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The incorporation of active pharmaceutical ingredients (APIs) into multicomponent solid forms (such as salts and co-crystals) or liquid forms (such as ionic liquids (ILs) or deep eutectic mixtures) is important in optimizing the efficacy and delivery of APIs. However, there is a current debate regarding the classification of these multicomponent systems based on their ionicity which could interfere with their consideration in important applications. Multicomponent systems of intermediate ionicity can show a combination of properties, leading to behavior that is neither strictly typical of either purely ionic or purely neutral compounds, nor easily described as intermediate between the two. In this perspective, we attempt to illustrate the problems in classifying multicomponent APIs based on one of two categories by discussing selected literature regarding solid and liquid multicomponent APIs and presenting the crystal structures of some relevant systems as case studies. It is clear that a focus on restrictive nomenclature carries with it the risk that a thorough examination of the physicochemical properties of the compounds will be overlooked.

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Sponge classification has long been based mainly on morphocladistic analyses but is now being greatly challenged by more than 12 years of accumulated analyses of molecular data analyses. The current study used phylogenetic hypotheses based on sequence data from 18S rRNA, 28S rRNA, and the CO1 barcoding fragment, combined with morphology to justify the resurrection of the order Axinellida Lévi, 1953. Axinellida occupies a key position in different morphologically derived topologies. The abandonment of Axinellida and the establishment of Halichondrida Vosmaer, 1887 sensu lato to contain Halichondriidae Gray, 1867, Axinellidae Carter, 1875, Bubaridae Topsent, 1894, Heteroxyidae Dendy, 1905, and a new family Dictyonellidae van Soest et al., 1990 was based on the conclusion that an axially condensed skeleton evolved independently in separate lineages in preference to the less parsimonious assumption that asters (star-shaped spicules), acanthostyles (club-shaped spicules with spines), and sigmata (C-shaped spicules) each evolved more than once. Our new molecular trees are congruent and contrast with the earlier, morphologically based, trees. The results show that axially condensed skeletons, asters, acanthostyles, and sigmata are all homoplasious characters. The unrecognized homoplasious nature of these characters explains much of the incongruence between molecular-based and morphology-based phylogenies. We use the molecular trees presented here as a basis for re-interpreting the morphological characters within Heteroscleromorpha. The implications for the classification of Heteroscleromorpha are discussed and a new order Biemnida ord. nov. is erected.