621 research outputs found
A multipurpose Hopf deformation of the Algebra of Feynman-like Diagrams
We construct a three parameter deformation of the Hopf algebra
. This new algebra is a true Hopf deformation which reduces to
on one hand and to on the other, relating
to other Hopf algebras of interest in contemporary physics.
Further, its product law reproduces that of the algebra of polyzeta functions.Comment: 5 page
A Three Parameter Hopf Deformation of the Algebra of Feynman-like Diagrams
We construct a three-parameter deformation of the Hopf algebra \LDIAG. This
is the algebra that appears in an expansion in terms of Feynman-like diagrams
of the {\em product formula} in a simplified version of Quantum Field Theory.
This new algebra is a true Hopf deformation which reduces to \LDIAG for some
parameter values and to the algebra of Matrix Quasi-Symmetric Functions
(\MQS) for others, and thus relates \LDIAG to other Hopf algebras of
contemporary physics. Moreover, there is an onto linear mapping preserving
products from our algebra to the algebra of Euler-Zagier sums
Current Practice Patterns Regarding the Conduct of Thyroidectomy and Parathyroidectomy amongst Surgeons - A Survey Study
Background: Heterogeneity of surgical care exists among surgeons regarding the conduct of thyroidectomy and parathyroidectomy
Endothelial dysfunction and carotid atherosclerosis in Malawian adults: A cross-sectional study
Background and objective
In sub-Saharan Africa, data on prevalence, risk factors and pathobiology of carotid atherosclerosis are scarce. We aimed to investigate the relationship between biomarkers of endothelial dysfunction and carotid atherosclerosis.
Methods
Carotid ultrasound was performed in 66 patients. Plasma concentration of ICAM-1, PAI-1, VEGF, and soluble thrombomodulin were measured by ELISA. A univariable logistic regression analysis was performed to study the relationship between carotid atherosclerosis, biomarkers of endothelial dysfunction, and various demographic and clinical parameters of the participants.
Results
The mean age of the participants was 58.7 years (95% CI: 54.4–63.1). Carotid atherosclerosis was diagnosed in 39.4% (95% CI: 27.6–52.2). In the univariable logistic regression, the following factors were associated with carotid atherosclerosis: age > 45 years (OR = 12.0, 95% CI: 1.4–98.8, p = .02), hypertension (OR = 3.8, 95% CI: 1.2–12.1, p = .02), and high-level of soluble thrombomodulin (OR = 3.4, 95% CI: 1.2–10.0, p = .02).
Conclusions
There is an association between high levels of soluble thrombomodulin and carotid atherosclerosis in Malawian adults. Further studies with a larger sample size are needed to confirm our findings in other African populations
Feynman graphs and related Hopf algebras
In a recent series of communications we have shown that the reordering problem of bosons leads to certain combinatorial structures. These structures may be associated with a certain graphical description. In this paper, we show that there is a Hopf Algebra structure associated with this problem which is, in a certain sense, unique
Phenotypic Characterization of AmpC beta-lactamase among Cefoxitin Resistant Escherichia coli and Klebsiella pneumoniae Isolates in Accra, Ghana
AmpC ?-lactamases hydrolyze penicillins, cephalosporins and cephamycins and resist inhibition by clavulanate, sulbactam, and tazobactam. Strains with AmpC genes are inherently resistant to multiple agents, making the selection of an effective antibiotic difficult. This present work sought to investigate the occurrence of AmpC beta-lactamases-producing phenotypes in E. coli and K. pneumoniae and their antimicrobial sensitivity profile. Four hundred K. pneumoniae and E. coli non-duplicate isolates were collected and their antibiotic sensitivity testing for cefoxitin and other 16 antibiotics were determined using Vitek 2 Compact System (bioMérieux, Marcy I’Etoile, France). The isolates resistant to cefoxitin were confirmed as AmpC beta-lactamases-producing phenotypes with disk synergy testing (DST) using cefotaxime or ceftazidime with or without boronic acid. An increase in zone diameter of ?5mm in the presence of boronic acid indicates the presence of AmpC beta-lactamases in the test organism. The results showed that of the 50 cefoxitin resistant isolates screened from 400 bacterial isolates, 5(10%) were AmpC beta-lactamase-producers with 60%, 60%, 60%, 80% and 100% multiply antibiotic resistance in gentamicin, ciprofloxacin, norfloxacin, trimethoprim/sulfamethoxazole and tetracycline respectively. Nitrofurantoin which indicated 100% susceptibility with MIC90 of 32µg/ml may be a therapeutic option especially for non-life-threatening urinary tract infection. Imipenem was the antibiotic of choice with 100% susceptibility rates (MIC90 of ?1µg/ml). Though the insignificant (p>0.05) levels of AmpC beta-lactamase phenotypes may not require routine detection in health facilities, there is the need to implement evolutionary antibiotic administration policies and pragmatic infection control measures in the hospitals.     Keywords: AmpC beta-lactamase, Cefoxitin, ?-lactams, E. coli, K. pneumonia
The Reliability of Using Vitek 2 Compact System to Detect Extended-Spectrum Beta-lactamase-producing Isolates in Escherichia coli and Klebsiella pneumoniae in Accra, Ghana
Extended-spectrum beta-lactamases (ESBLs) are plasmid-mediated beta-lactamases that are capable of hydrolysing ?-lactams except carbapenems and cephamycins. The global increased prevalence of ESBL-producing bacteria creates an urgent need for laboratory diagnostic methods that will accurately and rapidly identify the presence of ESBL phenotypes in clinical isolates. The Vitek 2 System (bioMérieux, France) is a rapid automated microbiological system used for bacteria and yeast identification, antimicrobial susceptibility testing (AST), resistance mechanism detection and epidemiologic trending and reporting using its advanced expert system. This present work sought to determine the reliability of routinely using Vitek 2 System to accurately and rapidly detect ESBL-producing E. coli and K. pneumoniae in Accra. The ESBL phenotypes for 400 E. coli and K. pneumoniae isolates were determined using the Vitek 2 system and combined disc synergy method. The results were used to determine the sensitivity, specificity, negative predictive value and positive predictive value of the Vitek 2 ESBL test through comparative analysis with the combined disk synergy method which is the reference method recommended by CLSI. The findings of this work indicated that the sensitivity, specificity, positive predictive value and negative predictive value of Vitek 2 system was 98.5%, 98.9%, 99% and 98.5% respectively. Consequently, Vitek 2 system is a reliable semi-automated microbiology system which may be used for routine, accurate and rapid detection of ESBL strains in health facilities in Accra, Ghana. Keywords: Vitek 2 Compact System, Extended spectrum beta-lactamase, bioMérieux, E. coli and K. pneumoni
Re-Focusing - Building a Future for Entrepreneurial Education & Learning
The field of entrepreneurship has struggled with fundamental
questions concerning the subject’s nature and purpose. To whom and to
what means are educational and training agendas ultimately directed?
Such questions have become of central importance to policy makers,
practitioners and academics alike. There are suggestions that university
business schools should engage more critically with the lived experiences
of practising entrepreneurs through alternative pedagogical approaches
and methods, seeking to account for and highlighting the social, political
and moral aspects of entrepreneurial practice. In the UK, where funding in
higher education has become increasingly dependent on student fees,
there are renewed pressures to educate students for entrepreneurial
practice as opposed to educating them about the nature and effects of
entrepreneurship. Government and EU policies are calling on business
schools to develop and enhance entrepreneurial growth and skill sets, to
make their education and training programmes more proactive in
providing innovative educational practices which help and facilitate life
experiences and experiential learning. This paper makes the case for
critical frameworks to be applied so that complex social processes
become a source of learning for educators and entrepreneurs and so that
innovative pedagogical approaches can be developed in terms both of
context (curriculum design) and process (delivery methods)
Phenotypic Determination and Antimicrobial Resistance Profile of Extended Spectrum Beta-lactamases in Escherichia coli and Klebsiella pneumoniae in Accra, Ghana
Extended-spectrum beta-lactamases (ESBLs) are plasmid-mediated beta lactamases commonly found in the Enterobacteriaceae that are capable of hydrolysing ?-lactams except carbapenems and cephamycins. ESBLs confer resistance to several non-ß-lactam antibiotics. ESBL-producing organisms appear susceptible to cephalosporins in vitro using conventional breakpoints but ineffective in vivo. This work sought to determine the occurrence of ESBL in E. coli and K. pneumoniae and their antibiotic resistance profile. Four hundred K. pneumoniae and E. coli non-duplicate isolates were collected at the Central Laboratory of Korle Bu Teaching Hospital and Advent Clinical Laboratories. They were definitively identified and their minimum inhibition concentration and antibiotic sensitivity testing for 17 antibiotics were determined using Vitek 2 Compact System (bioMérieux, Marcy I’Etoile, France). The isolates were confirmed as ESBL-producing strains using the Combination Disk Synergy Method. The results indicated that 202 (50.5%) of the bacterial isolates were ESBL-producing phenotypes with high resistant to gentamicin, ciprofloxacin, tetracycline and trimethoprim/sulfamethoxazole indicating 82.2%, 79.7%, 70.8% and 97% resistant rates respectively. imipenem and amikacin were the antibiotics of choice with 99% and 94.1% susceptibility rates (MIC90 of ?1µg/ml and 4µg/ml respectively). It is imperative to routinely detect ESBL-phenotypes in health facilities, implement appropriate antibiotic administration policy and infection control measures in the hospitals.  Keywords: Extended Spectrum Beta-lactamase, Antimicrobial Resistance, ?-lactams, K. pneumoniae, E. col
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