1,179 research outputs found
International standards for early fetal size and pregnancy dating based on ultrasound measurement of crown-rump length in the first trimester of pregnancy.
No full textOBJECTIVES: There are no international standards for relating fetal crown-rump length (CRL) to gestational age (GA), and most existing charts have considerable methodological limitations. The INTERGROWTH-21(st) Project aimed to produce the first international standards for early fetal size and ultrasound dating of pregnancy based on CRL measurement.
METHODS: Urban areas in eight geographically diverse countries that met strict eligibility criteria were selected for the prospective, population-based recruitment, between 9 + 0 and 13 + 6 weeks' gestation, of healthy well-nourished women with singleton pregnancies at low risk of fetal growth impairment. GA was calculated on the basis of a certain last menstrual period, regular menstrual cycle and lack of hormonal medication or breastfeeding in the preceding 2 months. CRL was measured using strict protocols and quality-control measures. All women were followed up throughout pregnancy until delivery and hospital discharge. Cases of neonatal and fetal death, severe pregnancy complications and congenital abnormalities were excluded from the study.
RESULTS: A total of 4607 women were enrolled in the Fetal Growth Longitudinal Study, one of the three main components of the INTERGROWTH-21(st) Project, of whom 4321 had a live singleton birth in the absence of severe maternal conditions or congenital abnormalities detected by ultrasound or at birth. The CRL was measured in 56 women at < 9 + 0 weeks' gestation; these were excluded, resulting in 4265 women who contributed data to the final analysis. The mean CRL and SD increased with GA almost linearly, and their relationship to GA is given by the following two equations (in which GA is in days and CRL in mm): mean CRL = -50.6562 + (0.815118 × GA) + (0.00535302 × GA(2) ); and SD of CRL = -2.21626 + (0.0984894 × GA).
GA estimation is carried out according to the two equations: GA = 40.9041 + (3.21585 × CRL(0.5) ) + (0.348956 × CRL); and SD of GA = 2.39102 + (0.0193474 × CRL).
CONCLUSIONS: We have produced international prescriptive standards for early fetal linear size and ultrasound dating of pregnancy in the first trimester that can be used throughout the world
Transcritical rotating flow over topography
No full textThe flow of a one-and-a-half layer fluid over a three-dimensional obstacle of non-dimensional height M, relative to the lower layer depth, is investigated in the presence of rotation, the magnitude of which is measured by a non-dimensional parameter B (inverse Burger number). The transcritical regime in which the Froude number F, the ratio of the flow speed to the interfacial gravity wave speed, is close to unity is considered in the shallow-water (small-aspect-ratio) limit. For weakly rotating flow over a small isolated obstacle (M -> 0) a similarity theory is developed in which the behaviour is shown to depend on the parameters Gamma = (F - 1)M-2/3 and nu = (BM-1/3)-M-1/2. The flow pattern in this regime is determined by a nonlinear equation in which Gamma and nu appear explicitly, termed here the 'rotating transcritical small-disturbance equation' (rTSD equation, following the analogy with compressible gasdynamics). The rTSD equation is forced by 'equivalent aerofoil' boundary conditions specific to each obstacle. Several qualitatively new flow behaviours are exhibited, and the parameter reduction afforded by the theory allows a (Gamma, nu) regime diagram describing these behaviours to be constructed numerically. One important result is that, in a supercritical oncoming flow in the presence of sufficient rotation (nu greater than or similar to 2), hydraulic jumps can appear downstream of the obstacle even in the absence of an upstream jump. Rotation is found to have the general effect of increasing the amplitude of any existing downstream hydraulic jumps and reducing the lateral extent and amplitude of upstream jumps. Numerical results are compared with results from a shock-capturing shallow-water model, and the (Gamma, nu) regime diagram is found to give good qualitative and quantitative predictions of flow patterns at finite obstacle height (at least for M less than or similar to 0.4). Results are compared and contrasted with those for a two-dimensional obstacle or ridge, for which rotation also causes hydraulic jumps to form downstream of the obstacle and acts to attenuate upstream jumps
l-Gruppen und Bezout-Bereiche
No full textWir untersuchen die Strukturtheorie abelscher l-Gruppen im Hinblick auf ihre Beziehungen zur Teilbarkeit in Bezout-Bereichen und zu MV-Algebren. Hauptmotivation für die Arbeit ist die Jaffard-Ohm-Korrespondenz zwischen abelschen l-Gruppen und Bezout-Bereichen, und D. Mundici's funktorielle Äquivalenz zwischen abelschen l-Gruppen mit starker Einheit und MV-Algebren.
Mit Hilfe der Bewertungstheorie erhalten wir eine positive Antwort zum Problem von Conrad und Dauns (1969), ob ein Verbandsschiefkörper mit positiven Quadraten stets angeordnet ist. Als Gegenstück hierzu beweisen wir die Existenz gerichteter Algebren mit negativen Quadraten.
Für eine beliebige l-Gruppe verallgemeinern wir die Charakterisierung von o-Idealen in Rieszschen Räumen auf l-Ideale (2004). Mittels der Mundici-Korrespondenz zwischen l-Gruppen und MV-Algebren erhalten wir eine negative Entscheidung einer Frage von Belluce (1986) über Prim-Annihilatoren in MV-Algebren.
Für eine abelsche l-Gruppe G konstruieren wir eine dichte Einbettung von G in eine lateral vollständige abelsche l-Gruppe E(G) mittels Garbentheorie. Falls G archimedisch ist, beweisen wir, dass E(G) die laterale Vervollständigung von G ist, während dies im Allgemeinen falsch zu sein scheint. Als Nebenprodukt erhalten wir einen eleganten Beweis des Bernauschen Einbettungssatzes für Archimedische l-Gruppen. Ist G die Teilbarkeitsgruppe eines Bezout-Bereichs D, so zeigen wir, dass Spec(D) zum Spektrum Spec*(G) topologisch dual ist im Sinne von Hochster.
Wir studieren die C-Topologie abelscher l-Gruppen mit Blick auf Bezout-Bereiche und MV-Algebren. Dabei korrigieren wir zwei Lemmata von Gusi\'c (1998), was zu einer Verallgemeinerung eines seiner Hauptergebnisse führt.
Schliesslich beantworten wir eine Frage von Dumitrescu, Lequain, Mott und Zafrullah (2001), indem wir zeigen, dass die Jaffard-Ohm Korrespondenz für abelsche fast-l-Gruppen nicht gilt.We study the relationship between l-groups, Bezout domains, and MV-algebras. Our main motivation and starting point has been the Jaffard-Ohm correspondence between Abelian l-groups and Bezout domains and Mundici's equivalence between Abelian unital l-groups and MV-algebras.
Using valuation theory, we give a positive answer to Conrad and Dauns' problem (1969) whether a lattice-ordered skew-field with positive squares is linearly ordered. As a counterpart, we prove the existence of directed algebras with negative squares. For an arbitrary l-group, we give some characterizations of l-ideals in terms of absolute values, generalizing a similar result for o-ideals in Riesz spaces (2004).
A number of ring-theoretical notions and properties are introduced for l-groups and MV-algebras. Using the correspondence between l-groups and MV-algebras, we answer a question of Belluce (1986) on prime annihilators in MV-algebras in the negative.
For an Abelian l-group G, we construct a dense embedding of G into a laterally complete Abelian l-group E(G) by means of sheaf theory. In case G is Archimedean, we prove that E(G) is the lateral completion of G, while in general, this seems to be false. As a byproduct, we get a natural and elegant proof of Bernau's celebrated embedding theorem for Archimedean l-groups. If G is the group of divisibility of a B\'ezout domain D, we show that Spec(D) is related to a quasi-compact topology on Spec*(G) which turns out to be the Hochster dual" of the spectral topology.
We study the C-topology on Abelian l-groups and apply it to Bezout domains and MV-algebras. We correct two lemmas of Gusi\'c (1998) which leads to a generalization of one of his main results.
Finally, we answer a question of Dumitrescu, Lequain, Mott and Zafrullah (20019 which shows that the Jaffard-Ohm correspondence does not hold for Abelian almost l-groups
Non-dispersive and weakly dispersive single-layer flow over an axisymmetric obstacle: the equivalent aerofoil formulation
No full textNon-dispersive and weakly dispersive single-layer flows over axisymmetric obstacles, of non-dimensional height M measured relative to the layer depth, are investigated. The case of transcritical flow, for which the Froude number F of the oncoming flow is close to unity, and that of supercritical flow, for which F > 1, are considered. For transcritical flow, a similarity theory is developed for small obstacle height and, for non-dispersive flow, the problem is shown to be isomorphic to that of the transonic flow of a compressible gas over a thin aerofoil. The non-dimensional drag exerted by the obstacle on the flow takes the form D(Gamma)M-5/3, where Gamma = (F - 1)M-2/3 is a transcritical similarity parameter and D is a function which depends on the shape of the 'equivalent aerofoil' specific to the obstacle. The theory is verified numerically by comparing results from a shock-capturing shallow-water model with corresponding solutions of the transonic small-disturbance equation, and is found to be generally accurate for M less than or similar to 0.4 and vertical bar Gamma vertical bar less than or similar to 1. In weakly dispersive flow the equivalent aerofoil becomes the boundary condition for the Kadomtsev-Petviashvili equation and (multiple) solitary waves replace hydraulic jumps in the resulting flow patterns.For Gamma greater than or similar to 1.5 the transcritical similarity theory is found to be inaccurate and, for small M, flow patterns are well described by a supercritical theory, in which the flow is determined by the linear solution near the obstacle. In this regime the drag is shown to be c(d)M(2)/(F root F-2 - 1), where c(d) is a constant dependent on the obstacle shape. Away from the obstacle, in non-dispersive flow the far-field behaviour is known to be described by the N-wave theory of Whitham and in dispersive flow by the Kortewegde Vries equation. In the latter case the number of emergent solitary waves in the wake is shown to be a function of A = 3M/(2 delta(2) root F-2 - 1), where delta is the ratio of the undisturbed layer depth to the radial scale of the obstacle
The growth hormone 1 GH1:c.457C>G mutation is associated with intramuscular and rump fat distribution in a large sample of Australian feedlot cattle
No full textThe GH1:c.457C>G exon 5 missense mutation in the bovine growth hormone 1 (GH1) gene that causes the replacement of leucine (L) with valine (V) was investigated in 1027 cattle with primarily Angus and Shorthorn breeding from Australian feedlots. The allele frequency of the GH1:c.457C allele was 0.77 in Angus and 0.76 in Shorthorn. The GH1:c.457C allele was associated with lower marbling (P = 0.0472), and the average effect of allele substitution was -0.22 of a phenotypic standard deviation. This allele was also associated with slightly higher rump fat (P = 0.0541) and the average effect of allele substitution was 0.11 SD. Marbling and rump fat were not strongly correlated (r = 0.097, P 0.1). Given these relationships, the differences between GH1 alleles could be the result of differential deposition of fat in fat depots
Using ultrasound measurements of rump fat to assess nutritional condition of woodland caribou in northern British Columbia, Canada
No full textBody reserves (fat and protein) of cervids are important to the reproductive success of individuals, and therefore may limit productivity of populations. We used a portable ultrasound machine to measure thickness of rump fat for 39 woodland caribou (Rangifer tarandus caribou) captured in the winters (January–February) of 2003 and 2004. We compared thickness of rump fat between pregnant and non-pregnant individuals in the Besa-Prophet drainage of northern British Columbia, Canada. Thirty-eight of the 39 females captured in British Columbia were adults and 34 of the adult caribou were pregnant (89.5 ± 5.1%, x– ± binomial SE). Pregnant individuals had more rump fat (0.60 ± 0.067 cm) than nonpregnant animals (0.20 ± 0.029 cm). Recognizing that deposition and mobilization of fat vary with age and possibly across the winter season, ultrasonography can be used as a non-invasive technique in the field to assist in estimating body fat of caribou
STAT3 is required for IL-6-gp130-dependent activation of hepcidin in vivo
No full textBBackground & Aims: Hepcidin is a peptide hormone that is central to the regulation of iron homeostasis. In response to interleukin 6 (IL-6), hepatocytes produce hepcidin that decreases iron release/transfer from enterocytes and macrophages and causes hypoferremia. To clarify the molecular pathways involved in hepcidin activation by IL-6, we used different mice strains in which the main IL-6/gp130 signaling pathways have been genetically disrupted. Methods: We generated mice with hepatocyte-specific deletion of the IL-6 signaltransducing gp130 receptor (alfgp130 (LoxP/LoxP)), with a gp130 receptor lacking the essential region for STAT1 and -3 activation (alrpCre gp130(Delta STAT/LoxP)) or mice expressing a gp130 allele lacking the essential tyrosine for RAS-MAPK activation (alfpCregp130(Y757F/LoxP)). We studied gp130-dependent pathways and hepcidin mRNA expression by Western blot, reverse-transcription polymerase chain reaction, and Northern blot in vivo and ex vivo. Results: IL-6 stimulated phospho STAT3, serum amyloid A (SAA), and suppressor of cytokine signaling 3 (SOCS3) expression in livers of mild-type and alfpCregp130(Y757F/LoxP) mice, whereas this response was blocked in alfpCre gp130(LoxP/LoxP) and alfpCre gp130(Delta STAT/LoxP) mice. In wild-type and alfpCregP130(Y757F/LoxP) animals, significantly higher hepcidin mRNA expression was found 3 to 6 hours after IL-6 stimulation. In contrast, no IL-6-dependent regulation of hepcidin mRNA expression was found in alfpgp130(Delta STAT/LoxP) and AlfpCre gp130 (LoxP.LoxP) animals. In primary hepatocytes, higher hepcidin mRNA expression after IL-6 stimulation was only observed when gp130-STAT3-dependent signaling was intact. Conclusions: We have demonstrated that both in vivo and in vitro STAT3 is the key transcription factor responsibl
Standardisation of crown-rump length measurement.
No full textCorrect estimation of gestational age is essential for any study of ultrasound biometry and for everyday clinical practice. However, inconsistency in pregnancy dating may occur through differences in measurement methods or errors during measurement. In the INTERGROWTH-21(st) Project, pregnancies are dated by the last menstrual period, provided that it is certain and associated with a regular menstrual cycle, and the gestational age by dates concurs with a first-trimester ultrasound crown-rump length (CRL) estimation. Hence, there was a need to standardise CRL measurement methodology across the study sites in this international, multicentre project to avoid systematic differences in dating. To achieve uniformity we undertook the following steps: the ultrasound technique was standardised by disseminating an illustrated, operating manual describing CRL plane landmarks and calliper application, and posters describing the correct acquisition technique were disseminated for quick reference. To ensure that all ultrasonographers understood the methodology, they forwarded a log-book to the INTERGROWTH-21(st) Ultrasound Coordinating Unit, containing the answers to a written test on the manual material and five images of a correctly acquired CRL. Interpretation of CRL was also standardised by ensuring that the same CRL regression formula was used across all study sites. These methods should minimise potential systematic errors in dating associated with pooling data from different health institutions, and represent a model for standardising CRL measurement in future studies
On the enumeration of finite -algebras
No full textWe use Constraint Satisfaction Methods to construct and enumerate finite
-algebras up to isomorphism. These objects were recently introduced by Rump
and appear in Garside theory, algebraic logic, and the study of the
combinatorial Yang-Baxter equation. There are 377322225 isomorphism classes of
-algebras of size eight. The database constructed suggest the existence of
bijections between certain classes of -algebras and well-known combinatorial
objects. On the one hand, we prove that Bell numbers enumerate isomorphism
classes of finite linear -algebras. On the other hand, we also prove that
finite regular -algebras are in bijective correspondence with
infinite-dimensional Young diagrams.Comment: 17 pages, 3 tables, 2 figures. Postprint versio
Merchants, commissioners and wardmasters : municipal politics in Cape Town, 1840-1854
No full textBibliography: leaves 260-272.Merchants,Commissioners and Wardmasters: Municipal Politics in Cape Town, 1840-854 explores the social, political and economic changes and conflicts that helped to determine Cape Town's evolution in the mid nineteenth century. The focus lies on the dominant classes who were involved in municipal and colonial affairs. This study critically examines the thesis, first propounded by Tony Kirk, of class rivalry between Cape Town's 'aristocracy', the mercantile elite, and the rising commercial middle class which dominated the municipal executive. It also investigates the intra-institutional relations between the municipal commissioners (the executive) and wardmasters (members of the junior board of the municipality), and the role played by the municipality in Cape politics. In filling a gap that exists in the growing body of academic research on the history of Cape Town, this dissertation aims to make an original contribution to the field of South African urban history
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