527 research outputs found
Review of travels into print: exploration, writing, and publishing with John Murray, 1773-1859
A Technique for generating Feynman Diagrams
We present a simple technique that allows to generate Feynman diagrams for
vector models with interactions of order and similar models (Gross-Neveu,
Thirring model), using a bootstrap equation that uses only the free field value
of the energy as an input. The method allows to find the diagrams to, in
principle, arbitrarily high order and applies to both energy and correlation
functions. It automatically generates the correct symmetry factor (as a
function of the number of components of the field) and the correct sign for any
diagram in the case of fermion loops. We briefly discuss the possibility of
treating QED as a Thirring model with non-local interaction.Comment: 19 pages, LateX, To be published in Z. f. Phys.
Pseudomonas aeruginosa in cystic fibrosis patients : acquisition, early diagnosis and efficacy of eradication treatment
Varicella paediatric hospitalisations in Belgium : a 1-year national survey
Background: Varicella universal vaccination (UV) has been implemented in many countries for several years. Nevertheless, varicella UV remains debated in Europe and few data are available on the real burden of infection. We assessed the burden of varicella in Belgium through analysis of hospitalised cases during a 1-year period.
Methods: Data on children admitted to hospital with varicella were collected through a national network from November 2011 to October 2012. Inclusion criteria were either acute varicella or related complications up to 3 weeks after the rash.
Results: Participation of 101 hospitals was obtained, covering 97.7% of the total paediatric beds in Belgium. 552 children were included with a median age of 2.1 years. Incidence of paediatric varicella hospitalisations reached 29.5/105 person-years, with the highest impact among those 0-4 years old (global incidence and odds of hospitalisation: 79/105 person-years and 1.6/100 varicella cases, respectively). Only 14% (79/552) of the cohort had an underlying chronic condition. 65% (357/552) of children had >= 1 complication justifying their admission, 49% were bacterial superinfections and 10% neurological disorders. Only a quarter of children (141/ 552) received acyclovir. Incidence of complicated hospitalised cases was 19/10(5) person-years. Paediatric intensive care unit admission and surgery were required in 4% and 3% of hospitalised cases, respectively. Mortality among Belgian paediatric population was 0.5/106 and fatality ratio 0.2% among our cohort.
Conclusions: Varicella demonstrated a substantial burden of disease in Belgian children, especially among the youngest. Our thorough nationwide study, run in a country without varicella UV, offers data to support varicella UV in Belgium
Impact of Fusarium mycotoxins on in vitro activity of major hepatic cytochrome P450 biotransformation enzymes in pigs
Resistance assessment and safeguarding the efficacy : dose optimalization of enrofloxacin for the treatment of colibacillosis in broilers
Large N limit of O(N) vector models
Using a simple identity between various partial derivatives of the energy of
the vector model in 0+0 dimensions, we derive explicit results for the
coefficients of the large N expansion of the model. These coefficients are
functions in a variable , which is the expectation value of the two
point function in the limit . These functions are analytic and have
only one (multiple) pole in . We show to all orders that these
expressions obey a given general formula. Using this formula it is possible to
derive the double scaling limit in an alternative way. All the results obtained
for the double scaling limit agree with earlier calculations. (to be published
in Physics Letters B)Comment: 12 page
Characterization of porcine hepatic and intestinal drug metabolizing CYP450 : comparison with human orthologues from a quantitative, activity and selectivity perspective
Over the past two decades, the pig has gained attention as a potential model for human drug metabolism. Cytochrome P450 enzymes (CYP450), a superfamily of biotransformation enzymes, are pivotal in drug metabolism. Porcine CYP450 has been demonstrated to convert typical substrates of human CYP450. Nevertheless, knowledge and insight into porcine CYP450 quantity and substrate selectivity is scant, especially regarding intestinal CYP450. The current study aimed to map the quantities of hepatic and intestinal CYP450 in the conventional pig by using a proteomic approach. Moreover, the selectivity of the six most common used probe substrates (phenacetin, coumarin, midazolam, tolbutamide, dextromethorphan, and chlorzoxazone) for drug metabolizing enzyme subfamilies (CYP1A, CYP2A, CYP3A, CYP2C, CYP2D and CYP2E respectively), was investigated. Hepatic relative quantities were 4% (CYP1A), 31% (CYP2A), 14% (CYP3A), 10% (CYP2C), 28% (CYP2D) and 13% (CYP2E), whereas for the intestine only duodenal CYP450 could be determined with 88% for CYP3A and 12% for CYP2C. Furthermore, the results indicate that coumarin (CYP2A), midazolam (CYP3A), tolbutamide (CYP2C), and dextromethorphan (CYP2D) are as selective for porcine as for human CYP450. However, phenacetin (CYP1A2) and chlorzoxazone (CYP2E1) are less selective for the specific enzyme, despite similarities in selectivity towards the different enzymes involved compared to humans
A simple algorithm for automatic Feynman diagram generation
An algorithm for the automatic Feynman diagram (FD) generation is presented
in this paper. The algorithm starts directly from the definition formula of FD,
and is simple in concept and easy for coding. The symmetry factor for each FD
is naturally generated. It is expected to bring convenience for the researchers
who are studying new calculation techniques or making new calculation tools and
for the researchers who are studying effective field theory. A C-program made
from the algorithm is also presented, which is short, fast, yet very general
purpose: it receives arbitrary user defined model and arbitrary process as
input and generates FD's at any order.Comment: 11 pages, 2 figure
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