4,046 research outputs found
Phylogenetic relationships of African Caecilians (Amphibia: Gymnophiona): insights from mitochondrial rRNA gene sequences
Africa (excluding the Seychelles) has a diverse caecilian fauna, including the endemic family Scolecomorphidae and six endemic genera of the more cosmopolitan Caeciliidae. Previous molecular phylogenetic studies have not included any caecilians from the African mainland. Partial 12S and 16S mitochondrial gene sequences were obtained for two species of the endemic African Scolecomorphidae and five species and four genera of African Caeciliids, aligned against previously reported sequences for 16 caecilian species, and analysed using parsimony, maximum likelihood, Bayesian and distance methods. Results are in agreement with traditional taxonomy in providing support for the monophyly of the African Caeciliid genera Boulengerula and Schistometopum and for the Scolecomorphidae. They disagree in indicating that the Caeciliidae is paraphyletic with respect to the Scolecomorphidae. Although more data from morphology and/or molecules will be required to resolve details of the interrelationships of the African caecilian genera, the data provide strong support for at least two origins of caecilians in which the eye is reduced and covered with bone, and do not support the hypotheses that the caecilian assemblages of Africa, and of East and of West Africa are monophyletic
Ten myths about character, virtue and virtue education â plus three well-founded misgivings
Initiatives to cultivate character and virtue in moral education at school continue to provoke sceptical responses. Most of those echo familiar misgivings about the notions of character, virtue and education in virtue â as unclear, redundant, old-fashioned, religious, paternalistic, anti-democratic, conservative, individualistic, relative and situation dependent. I expose those misgivings as âmythsâ, while at the same time acknowledging three better-founded historical, methodological and practical concerns about the notions in question
Existence of positive solutions of a superlinear boundary value problem with indefinite weight
We deal with the existence of positive solutions for a two-point boundary
value problem associated with the nonlinear second order equation
. The weight is allowed to change its sign. We assume
that the function is
continuous, and satisfies suitable growth conditions, so as the case
, with , is covered. In particular we suppose that is
large near infinity, but we do not require that is non-negative in a
neighborhood of zero. Using a topological approach based on the Leray-Schauder
degree we obtain a result of existence of at least a positive solution that
improves previous existence theorems.Comment: 12 pages, 4 PNG figure
High-frequency oscillatory ventilation in pediatric acute hypoxemic respiratory failure: disease-specific morbidity survival analysis.
BackgroundMultiple ventilatory strategies for acute hypoxemic respiratory failure (AHRF) in children have been advocated, including high-frequency oscillatory ventilation (HFOV). Despite the frequent deployment of HFOV, randomized controlled trials remain elusive and currently there are no pediatric trials looking at its use. Our longitudinal study analyzed the predictive clinical outcome of HFOV in pediatric AHRF given disease-specific morbidity.MethodsA retrospective 8-year review on pediatric intensive care unit admissions with AHRF ventilated by HFOV was performed. Primary outcomes included survival, morbidity, length of stay (LOS), and factors associated with survival or mortality.ResultsA total of 102 patients underwent HFOV with a 66 % overall survival rate. Survivors had a greater LOS than nonsurvivors (p = 0.001). Mortality odds ratio (OR) for patients without bronchiolitis was 8.19 (CI = 1.02, 65.43), and without pneumonia it was 3.07 (CI = 1.12, 8.39). A lower oxygenation index (OI) after HFOV commencement and at subsequent time points analyzed predicted survival. After 24 h, mortality was associated with an OI > 35 [OR = 31.11 (CI = 3.25, 297.98)]. Sepsis-related mortality was associated with a higher baseline FiO(2) (0.88 vs. 0.65), higher OI (42 vs. 22), and augmented metabolic acidosis (pH of 7.25 vs. 7.32) evaluated 4 h on HFOV (p < 0.05).ConclusionHigh-frequency oscillatory ventilation may be safely utilized. It has a 66 % overall survival rate in pediatric AHRF of various etiologies. Patients with morbidity limited to the respiratory system and optimized oxygenation indices are most likely to survive on HFOV
From the test tube to the World Wide Web - The cleavage specificity of the proteasome
Diese Dissertation handelt von Proteasomen (von 'Protease' und dem griechischen 'soma' = Protein-schneidender Körper) und ihrer Rolle in der Regulierung von Immunantworten. Proteasomen sind fassförmige, molekulare Maschinen (Enzyme), die in jeder Körperzelle zu finden sind. Ihre Aufgabe ist es, Proteine klein zu hacken, so Ă€hnlich wie eine HĂ€ckselmaschine, die Ăste und Zweige in kleine StĂŒcke schneidet. Die kleinen ProteinstĂŒcke können zur ZelloberflĂ€che transportiert und dort den zu den weiĂen Blutkörperchen gehörenden T-Zellen prĂ€sentiert werden. Wenn eine Körperzelle 'krank' ist (d.h. sie ist zu einer Tumorzelle geworden oder ist mit Krankheitserregern wie Viren oder Bakterien infiziert), sehen die Proteinfragmente auf der ZelloberflĂ€che anders aus. T-Zellen werden dadurch aktiviert, die 'kranke' Körperzelle zum Wohl des Gesamtorganismus abzutöten.
WĂ€hrend der Forschung fĂŒr meine Diplomarbeit (April-Dez. 1997) und meine Doktorarbeit (Jan. 1998-Dez. 2000) versuchte ich im Detail zu klĂ€ren, wie Proteine von Proteasomen klein geschnitten werden. Ich hatte GlĂŒck und konnte einige Regeln bestimmen, nach denen Proteasomen Proteine zerhĂ€ckseln. Diese Regeln wurden als Grundlage fĂŒr die Vorhersage von Proteasomen-Schnitten herangezogen. Meine Forschungsergebnisse haben groĂen Nutzen fĂŒr die Entwicklung von Impfstoffen und die Vorhersage von Immunantworten.This dissertation deals with proteasomes (from 'protease' and Greek 'soma' = protein-chopping body) and their role in the regulation of immune responses. Proteasomes are barrel-shaped molecular machines (enzymes) that are found in every cell of the body. Their job is to chop up proteins, much like a garden shredder that cuts twigs and branches into small pieces. The small protein pieces can be transported to the cell surface to be presented to T-cells, immune cells that constitute a part of the white blood cells. If a body cell is 'sick' (i.e. it has turned into a tumor cell or is infected by pathogens such as viruses or bacteria), the protein fragments on the cell surface look different. They therefore can activate T-cells to kill the diseased cell for the good of the whole organism.
During the research for my Diploma thesis (April-Dec. 1997) and my Ph.D. thesis (Jan. 1998-Dec. 2000) I tried to find out more about how exactly proteins are cleaved by proteasomes. I was lucky and could determine some of the rules that proteasomes follow to chop up proteins. These rules were used as a basis for the prediction of proteasome cleavages. My results have important implications for vaccine development and the prediction of immune responses
Intergenerational justice of what: welfare, resources or capabilities?
An important aspect of intergenerational justice concerns the specification of a 'currency of advantage' that can be used to evaluate distributive outcomes across time. Environmental theorists have introduced several innovative currencies of justice in recent years, such as ecological space and critical natural capital. However they have often downplayed the application of established currencies (such as welfare, resources or capabilities) to issues of futurity. After exploring the merits of a number of rival currencies, it is argued that the currency of 'capabilities to function' provides a promising basis for a theory of justice that takes seriously the rights and duties of intergenerational justice
Benzo-fused Tri[8]annulenes as Molecular Models of Cubic Graphite
Cyclotrimerization of 9,10âdibromoâ9,10âdihydrodibenzo[3,4:7,8]cycloocta[1,2âl]phenanthrene with potassium tertâbutoxide in the presence of a transitionâmetal catalyst afforded two polycyclic aromatic hydrocarbon stereoisomers consisting of three cyclooctatetraene (COT) moieties connected via a central benzene ring. Both isomeric tri[8]annulenes were obtained selectively through the choice of the catalyst: The α,α,αâform (Ru catalyst) displayed a threefold symmetrywith the COT subunits forming the side walls of a (chiral) molecular cup. In the thermodynamically more stable α,α,ÎČâisomer (Pd catalyst), one of the three boatâshaped COTs was flipped over and faced the opposite molecular hemisphere with respect to the central benzene ring as evidenced by crystal structure analysis. Both title compounds are small segments of âcubic graphiteâ, an elusive carbon allotrope
Normal Cones and Thompson Metric
The aim of this paper is to study the basic properties of the Thompson metric
in the general case of a real linear space ordered by a cone . We
show that has monotonicity properties which make it compatible with the
linear structure. We also prove several convexity properties of and some
results concerning the topology of , including a brief study of the
-convergence of monotone sequences. It is shown most of the results are
true without any assumption of an Archimedean-type property for . One
considers various completeness properties and one studies the relations between
them. Since is defined in the context of a generic ordered linear space,
with no need of an underlying topological structure, one expects to express its
completeness in terms of properties of the ordering, with respect to the linear
structure. This is done in this paper and, to the best of our knowledge, this
has not been done yet. The Thompson metric and order-unit (semi)norms
are strongly related and share important properties, as both are
defined in terms of the ordered linear structure. Although and
are only topological (and not metrical) equivalent on , we
prove that the completeness is a common feature. One proves the completeness of
the Thompson metric on a sequentially complete normal cone in a locally convex
space. At the end of the paper, it is shown that, in the case of a Banach
space, the normality of the cone is also necessary for the completeness of the
Thompson metric.Comment: 36 page
An archaeology of borders: qualitative political theory as a tool in addressing moral distance
Interviews, field observations and other qualitative methods increasingly are being used to inform the construction of arguments in normative political theory. This article works to demonstrate the strong salience of some kinds of qualitative material for cosmopolitan arguments to extend distributive boundaries. The incorporation of interviews and related qualitative material can make the moral claims of excluded others more vivid and possibly more difficult to dismiss by advocates of strong priority to compatriots in distributions. Further, it may help to promote the kind of perspective taking that has been associated with actually motivating a willingness to aid by individuals. Illustrative findings are presented from field work conducted for a normative project on global citizenship, including interviews with unauthorized immigrants and the analysis of artifacts left behind on heavily used migrant trails
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