838 research outputs found
Singular Behaviour of the Potts Model in the Thermodynamic Limit
The self-duality transformation is applied to the Fisher zeroes near the
critical point in the thermodynamic limit in the q>4 state Potts model in two
dimensions. A requirement that the locus of the duals of the zeroes be
identical to the dual of the locus of zeroes (i) recovers the ratio of specific
heat to internal energy discontinuity at criticality and the relationships
between the discontinuities of higher cumulants and (ii) identifies duality
with complex conjugation. Conjecturing that all zeroes governing ferromagnetic
critical behaviour satisfy the latter requirement, the full locus of Fisher
zeroes is shown to be a circle. This locus, together with the density of zeroes
is shown to be sufficient to recover the singular form of all thermodynamic
functions in the thermodynamic limit.Comment: Contribution to Lattice 97, LaTeX, 3 pages, 0 figure
Bacillus subtilis vegetative isolate surviving chlorine dioxide exposure: an elusive mechanism of resistance
Aims
Oxidizing agents such as chlorine dioxide are widely used microbicides, including for disinfection of medical equipment. We isolated a Bacillus subtilis isolate from a washer-disinfector whose vegetative form demonstrated unique resistance to chlorine dioxide (0·03%) and hydrogen peroxide (7·5%). The aim of this study was to understand the mechanisms of resistance expressed by this isolate.
Methods and Results
A range of resistance mechanisms were investigated in the B. subtilis isolate and a reference B. subtilis strain (ATCC 6051) to include bacterial cell aggregation, the presence of profuse exopolysaccharide (EPS), and the expression of detoxification enzymes. The basis of resistance of the isolate to high concentrations of oxidizing agents was not linked to the presence of endospores. Although, the presence of EPS, aggregation and expression of detoxification enzymes may play a role in bacterial survival to low concentrations of chlorine dioxide, it is unlikely that the mechanisms helped tested to survive the bactericidal effect of higher oxidizer concentrations.
Conclusions
Overall, the mechanisms conferring resistance to chlorine dioxide and hydrogen peroxide remains elusive. Based on recent advances in the mode of action of oxidizing agents and notably hydrogen peroxide, we postulate that additional efficient intracellular mechanisms may be involved to explain significant resistance to in-use concentrations of commonly used high-level disinfectants
Fisher Zeroes and Singular Behaviour of the Two Dimensional Potts Model in the Thermodynamic Limit
The duality transformation is applied to the Fisher zeroes near the
ferromagnetic critical point in the q>4 state two dimensional Potts model. A
requirement that the locus of the duals of the zeroes be identical to the dual
of the locus of zeroes in the thermodynamic limit (i) recovers the ratio of
specific heat to internal energy discontinuity at criticality and the
relationships between the discontinuities of higher cumulants and (ii)
identifies duality with complex conjugation. Conjecturing that all zeroes
governing ferromagnetic singular behaviour satisfy the latter requirement gives
the full locus of such Fisher zeroes to be a circle. This locus, together with
the density of zeroes is then shown to be sufficient to recover the singular
form of the thermodynamic functions in the thermodynamic limit.Comment: 10 pages, 0 figures, LaTeX. Paper expanded and 2 references added
clarifying duality relationships between discontinuities in higher cumulant
A national registry for juvenile dermatomyositis and other paediatric idiopathic inflammatory myopathies: 10 years' experience; the Juvenile Dermatomyositis National (UK and Ireland) Cohort Biomarker Study and Repository for Idiopathic Inflammatory Myopathies
Objectives: The paediatric idiopathic inflammatory myopathies (IIMs) are a group of rare chronic inflammatory disorders of childhood, affecting muscle, skin and other organs. There is a severe lack of evidence base for current treatment protocols in juvenile myositis. The rarity of these conditions means that multicentre collaboration is vital to facilitate studies of pathogenesis, treatment and disease outcomes. We have established a national registry and repository for childhood IIM, which aims to improve knowledge, facilitate research and clinical trials, and ultimately to improve outcomes for these patients.
Methods: A UK-wide network of centres and research group was established to contribute to the study. Standardized patient assessment, data collection forms and sample protocols were agreed. The Biobank includes collection of peripheral blood mononuclear cells, serum, genomic DNA and biopsy material. An independent steering committee was established to oversee the use of data/samples. Centre training was provided for patient assessment, data collection and entry.
Results: Ten years after inception, the study has recruited 285 children, of which 258 have JDM or juvenile PM; 86% of the cases have contributed the biological samples. Serial sampling linked directly to the clinical database makes this a highly valuable resource. The study has been a platform for 20 sub-studies and attracted considerable funding support. Assessment of children with myositis in contributing centres has changed through participation in this study.
Conclusions: This establishment of a multicentre registry and Biobank has facilitated research and contributed to progress in the management of a complex group of rare muscloskeletal conditions
Structure and evolution of the Demerara Plateau, offshore French Guiana : rifting, tectonic inversion and post-rift tilting at transform-divergent margins intersection
International audienceWe present the structure and evolution of the eastern part of the Demerara plateau, offshore French Guiana, from the analysis of geophysical data collected during GUYAPLAC cruise. This area is located at the intersection of a transform segment and a divergent segment of a continental margin related to the Early Cretaceous opening of the Equatorial Atlantic. The main structures are NNE-SSW to NNW-SSE trending normal faults on the eastern edge of the plateau, and WNW-ESE to NW-SE trending acoustic basement ridges on its northern edge. When replaced in their Albian position, these structures appear to be parallel to the coeval oceanic accretion axis and transform faults, respectively. The most striking structures are related to a post-rift but syn-transform tectonic inversion, producing E-W to WNW-ESE trending folds, sealed by a regional unconformity. This shortening can not be related to ridge push, but is probably related to a plate kinematic change 105 My ago, that modified the deformation in the vicinity of the transform fault. Late post-rift evolution also includes a significant Tertiary oceanward tilt of the edge of the Demerara plateau. The driving mechanism of this late tilt is unclear, but may be related to a lithospheric flexure resulting from the loading of the abyssal plain by the Orinoco and Amazon deep-sea fans
Analytical evidence for the absence of spin glass transition on self-dual lattices
We show strong evidence for the absence of a finite-temperature spin glass
transition for the random-bond Ising model on self-dual lattices. The analysis
is performed by an application of duality relations, which enables us to derive
a precise but approximate location of the multicritical point on the Nishimori
line. This method can be systematically improved to presumably give the exact
result asymptotically. The duality analysis, in conjunction with the
relationship between the multicritical point and the spin glass transition
point for the symmetric distribution function of randomness, leads to the
conclusion of the absence of a finite-temperature spin glass transition for the
case of symmetric distribution. The result is applicable to the random bond
Ising model with or Gaussian distribution and the Potts gauge glass on
the square, triangular and hexagonal lattices as well as the random three-body
Ising model on the triangular and the Union-Jack lattices and the four
dimensional random plaquette gauge model. This conclusion is exact provided
that the replica method is valid and the asymptotic limit of the duality
analysis yields the exact location of the multicritical pointComment: 11 Pages, 4 figures, 1 table. submitted to J. Phys. A Math. Theo
Intérêt de l’acide tranexamique en traitement d’urgence de première intention des crises d’angiœdème bradykinique sous IEC
INTRODUCTION: Episodes of acquired bradykinin-mediated angioedema due to angiotensin-converting enzyme (ACE) inhibitors may result in fatal outcomes. There is no consensus regarding emergency pharmacological management of these episodes. Treatment options include icatibant and C1INH concentrate. Tranexamic acid is administered for moderate episodes. Its efficacy in the treatment of ACE inhibitor-induced episodes of angioedema is not established. The aim of this retrospective study is to assess the benefits of emergency tranexamic acid administration in the management of ACE inhibitor-induced episodes of angioedema.
METHODS: Retrospective analysis of the medical files of patients who consulted between 2010 and 2016 in two French tertiary care hospitals for a bradykinic angioedema attributed to an ACE treatment. All of them had received tranexamic acid as a first line treatment.
RESULTS: Thirty three patients who had experienced severe episode of angioedema were included. Twenty seven patients showed significant improvement when treated with tranexamic acid alone. The six remaining patients were treated with icatibant (5/33) or C1INH concentrate (1/33), due to partial improvement after tranexamic acid therapy. None of the patients were intubated, no fatalities were recorded and no side effects were reported.
CONCLUSION: Tranexamic acid is an easily accessible and affordable therapy that may provide effective treatment for ACE inhibitor-induced episodes of angioedema. It may help while waiting for a more specific treatment (icatibant and C1INH concentrate) that is at times unavailable in emergency departments
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