2,141 research outputs found
Pseudo-rotations of the open annulus
In this paper, we study pseudo-rotations of the open annulus, \emph{i.e.}
conservative homeomorphisms of the open annulus whose rotation set is reduced
to a single irrational number (the angle of the pseudo-rotation). We prove in
particular that, for every pseudo-rotation of angle , the rigid
rotation of angle is in the closure of the conjugacy class of . We
also prove that pseudo-rotations are not persistent in topology for any
.Comment: 25 page
Some fossil ginkgophytes and a possible vojnovskyalean element from the Glossopteris flora of Vereeniging, Transvaal
Main articleA short historical review is given of previously described sites where plant fossils
occur in Lower Karroo beds at Vereeniging in the Southern Transvaal. Reference is made to the importance of these sites because of the outstanding discoveries made here in the past. Some new material from the same sites is described and several unusual elements in the Glossopteris flora of Vereeniging are recorded for the first time.
Leaves of a plant not previously recorded from Gondwanaland are provisionally
described under the term cf. Nephropsis on account of a strong resemblance to leaves of
the Russian Permian genus Nephropsis Zalessky.
The remaining specimens in the assemblage are tentatively placed in the genera
Ginkgoites Seward and Psygmophyllum Schimper respectively. Owing to the paucity of
material, type numbers are assigned in certain cases, instead of specific names. Specific
identification is attempted, however, in the case of four of the specimens, which are
provisionally assigned to Psygmophyllum kidstoni Seward.Non
On some "northern" elements in the Lower Gondwana flora of Vereeniging, Transvaal
Main articleA small assemblage of plant elements from the Lower Permian of Vereeniging, in the southern Transvaal, is described here. The assemblage is constituted of form-genera normally only found in the palaeo floristic regions of the northern hemisphere. The genera concerned are: Pecopteris (Asterotheca), Cladophlebis, Sphenophyllum and Psygmophyllum. The intermingling of these "Northern" elements with
the Glossopteris flora of Vereeniging serves to illustrate the mixed nature of this flora. Reference is made to similar mixed Gondwana floras elsewhere in Africa and also in South America.Non
Duodenal-Jejunal Bypass and Jejunectomy Improve Insulin Sensitivity in Goto-Kakizaki Diabetic Rats Without Changes in Incretins or Insulin Secretion
Gastric bypass surgery can dramatically improve type 2 diabetes. It has been hypothesized that by excluding duodenum and jejunum from nutrient transit, this procedure may reduce putative signals from the proximal intestine that negatively influence insulin sensitivity ( S I ). To test this hypothesis, resection or bypass of different intestinal segments were performed in diabetic Goto-Kakizaki and Wistar rats. Rats were randomly assigned to five groups: duodenal-jejunal bypass (DJB), jejunal resection (jejunectomy), ileal resection (ileectomy), pair-fed sham-operated, and nonoperated controls. Oral glucose tolerance test was performed within 2 weeks after surgery. Baseline and poststimulation levels of glucose, insulin, glucagon-like peptide 1 (GLP-1), and glucose-dependent insulinotropic polypeptide (GIP) were measured. Minimal model analysis was used to assess S I . S I improved after DJB ( S I = 1.14 ± 0.32 Ă 10 â4 min â1 â
pM â1 ) and jejunectomy ( S I = 0.80 ± 0.14 Ă 10 â4 min â1 â
pM â1 ), but not after ileectomy or sham operation/pair feeding in diabetic rats. Both DJB and jejunal resection normalized S I in diabetic rats as shown by S I levels equivalent to those of Wistar rats ( S I = 1.01 ± 0.06 Ă 10 â4 min â1 â
pM â1 ; P = NS). Glucose effectiveness did not change after operations in any group. While ileectomy increased plasma GIP levels, no changes in GIP or GLP-1 were observed after DJB and jejunectomy. These findings support the hypothesis that anatomic alterations of the proximal small bowel may reduce factors associated with negative influence on S I , therefore contributing to the control of diabetes after gastric bypass surgery
American consensus recommendations for gastric scintigraphy: curve fitting with only a few points remains an easy and accurate method to obtain reliable and reproducible gastric emptying estimates.
International audienceBACKGROUND: In 2008, American consensus recommendations for performing gastric emptying (GE) scintigraphy were published. It was recommended that data are acquired only at 0, 1, 2, and 4 h and that the results are expressed as percentages of meal retention. Until now, it was established that the GE time-activity curves should have many points (every 10, 15, or 20 min) to reflect the GE process accurately and to be optimally adjusted by a mathematical model. In this study, we have evaluated the curve fitting using only a few points as proposed by the consensus protocol. MATERIALS AND METHODS: GE scintigraphy tests of 224 patients were retrospectively analyzed. Two curve fittings were done for each patient, either using data acquired every 20 min or using data acquired every hour. A comparison of these two methods was made based on the values of the computed GE parameters. RESULTS: We observed strong correlations between the two methods (r=0.81-0.99, P<0.05). Using the Bland-Altman analysis, more than 95% of the differences were included in the mean difference 95% confidence interval. The mean differences were weak with a relatively small SD and Cohen's k coefficients ranging from 0.84 to 0.93, indicating an excellent agreement between the two methods. CONCLUSION: Our results showed the feasibility and accuracy of curve fitting using only a few points. The curve fitting is easy to perform and allows the computation of reliable and reproducible parameters that reflect the whole GE process
Direct sequencing of hepatitis A virus strains isolated during an epidemic in France
Direct sequencing of PCR products was used to study the VP1 region of the hepatitis A virus (HAV) genome (position 2199 to 2356) of nine strains isolated from human stools collected during a hepatitis A epidemic (western France, 1992), three strains from environmental samples (1990, 1991, and 1992), and two HAV cell culture isolates (the French strain CF53/Lyon and strain CLF). These viruses differed from CF53/Lyon (genotype I) by between 1 and 10.3%, and results indicated the existence of two groups of strains belonging to two different subgenotypes (IA and IB). With this sequencing technique it was possible to monitor the epidemiology of HAV and study its relations
A New Model of Social Class: Findings from the BBC's Great British Class Survey Experiment
The social scientific analysis of social class is attracting renewed interest given the accentuation of economic and social inequalities throughout the world. The most widely validated measure of social class, the Nuffield class schema, developed in the 1970s, was codified in the UKâs National Statistics Socio-Economic Classification (NS-SEC) and places people in one of seven main classes according to their occupation and employment status. This principally distinguishes between people working in routine or semi-routine occupations employed on a âlabour contractâ on the one hand, and those working in professional or managerial occupations employed on a âservice contractâ on the other. However, this occupationally based class schema does not effectively capture the role of social and cultural processes in generating class divisions. We analyse the largest survey of social class ever conducted in the UK, the BBCâs 2011 Great British Class Survey, with 161,400 web respondents, as well as a nationally representative sample survey, which includes unusually detailed questions asked on social, cultural and economic capital. Using latent class analysis on these variables, we derive seven classes. We demonstrate the existence of an âeliteâ, whose wealth separates them from an established middle class, as well as a class of technical experts and a class of ânew affluentâ workers. We also show that at the lower levels of the class structure, alongside an ageing traditional working class, there is a âprecariatâ characterised by very low levels of capital, and a group of emergent service workers. We think that this new seven class model recognises both social polarisation in British society and class fragmentation in its middle layers, and will attract enormous interest from a wide social scientific community in offering an up-to-date multi-dimensional model of social class
How far back do we need to look to capture diagnoses in electronic health records? A retrospective observational study of hospital electronic health record data
Objectives: Analysis of routinely collected electronic health data is a key tool for long-term condition research and practice for hospitalised patients. This requires accurate and complete ascertainment of a broad range of diagnoses, something not always recorded on an admission document at a single point in time. This study aimed to ascertain how far back in time electronic hospital records need to be interrogated to capture long-term condition diagnoses. /
Design: Retrospective observational study of routinely collected hospital electronic health record data. /
Setting: Queen Elizabeth Hospital Birmingham (UK)-linked data held by the PIONEER acute care data hub. /
Participants: Patients whose first recorded admission for chronic obstructive pulmonary disease (COPD) exacerbation (n=560) or acute stroke (n=2142) was between January and December 2018 and who had a minimum of 10 years of data prior to the index date. /
Outcome measures: We identified the most common International Classification of Diseases version 10-coded diagnoses received by patients with COPD and acute stroke separately. For each diagnosis, we derived the number of patients with the diagnosis recorded at least once over the full 10-year lookback period, and then compared this with shorter lookback periods from 1 year to 9 years prior to the index admission. /
Results: Seven of the top 10 most common diagnoses in the COPD dataset reached >90% completeness by 6 years of lookback. Atrial fibrillation and diabetes were >90% coded with 2â3 years of lookback, but hypertension and asthma completeness continued to rise all the way out to 10 years of lookback. For stroke, 4 of the top 10 reached 90% completeness by 5 years of lookback; angina pectoris was >90% coded at 7 years and previous transient ischaemic attack completeness continued to rise out to 10 years of lookback. /
Conclusion: A 7-year lookback captures most, but not all, common diagnoses. Lookback duration should be tailored to the conditions being studied
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