824 research outputs found
Avalanche frontiers in dissipative abelian sandpile model as off-critical SLE(2)
Avalanche frontiers in Abelian Sandpile Model (ASM) are random simple curves
whose continuum limit is known to be a Schramm-Loewner Evolution (SLE) with
diffusivity parameter . In this paper we consider the dissipative
ASM and study the statistics of the avalanche and wave frontiers for various
rates of dissipation. We examine the scaling behavior of a number of functions
such as the correlation length, the exponent of distribution function of loop
lengths and gyration radius defined for waves and avalanches. We find that they
do scale with the rate of dissipation. Two significant length scales are
observed. For length scales much smaller than the correlation length, these
curves show properties close to the critical curves and the corresponding
diffusivity parameter is nearly the same as the critical limit. We interpret
this as the ultra violet (UV) limit where corresponding to .
For length scales much larger than the correlation length we find that the
avalanche frontiers tend to Self-Avoiding Walk, the corresponding driving
function is proportional to the Brownian motion with the diffusion parameter
corresponding to a field theory with . This is the infra
red (IR) limit. Correspondingly the central charge decreases from the IR to the
UV point.Comment: 11 Pages, 6 Figure
Human cytochrome b5 reductase: structure, function, and potential applications
Cytochrome b5 reductase is a flavoprotein that is produced as two different isoforms that have different localizations.
The amphipathic microsomal isoform, found in all cell types with the exception of erythrocytes, consists of one
hydrophobic membrane-anchoring domain and a larger hydrophilic flavin catalytic domain. The soluble cytochrome
b5 reductase isoform, found in human erythrocytes, is a truncated protein that is encoded by an alternative transcript
and consists of the larger domain only. Cytochrome b5 reductase is involved in the transfer of reducing equivalents
from the physiological electron donor, NADH, via an FAD domain to the small molecules of cytochrome b5. This protein
has received much attention from researchers due to its involvement in many oxidation and reduction reactions, such
as the reduction of methemoglobin to hemoglobin. Autosomal cytochrome b5 reductase gene deficiency manifests
with the accumulation of oxidized Fe+3 and recessive congenital methemoglobinemia in humans. In this article,
we provide a comprehensive overview of the structure and function of cytochrome b5 reductase from different
eukaryotic sources and its potential use in the food industry, biosensor, and diagnostic areas
14C-urea breath test in patients undergoing anti-tuberculosis therapy
Aim: Urea breath test (UBT) is a non-invasive diagnostic test for detecting the presence of Helicobacter pylori (H pylori). In this study we evaluated the effect of anti-tuberculosis therapy on the results of 14C-UBT. Methods: Patients, with the diagnosis of tuberculosis (TB) who had a positive UBT at the point of starting anti-TB therapy, were included. None had a history of peptic ulcer disease or had taken antibiotics, bismuth compounds and/or PPI in the previous month. 14C-UBT was repeated at the end of the second month and the end of treatment period and one month after completion of treatment course. Results: Thirty-five patients (23 males) were enrolled. 14C-UBT was negative in all 35 patients (100) at the end of the second month and remained negative in 30 cases (85.7) at the end of the treatment course. One month after completion of treatment course, UBT remained negative in 13 patients (37.1). Conclusion: Our report underscores the need for caution while interpreting urea breath test results in patients undergoing anti-TB therapy. Furthermore, the combination of drugs used in this study resulted in H pylori eradication in a minority of patients. © 2005 The WJG Press and Elsevier Inc. All rights reserved
The anticancer agent prodigiosin is not a multidrug resistance protein substrate
The brilliant red pigments prodiginines are natural secondary metabolites that are produced
by select species of Gram-negative and Gram-positive bacteria. These molecules have
received significant attention due to their reported antibacterial, antifungal,
immunosuppressive, and anticancer activities. In this study, a Serratia marcescens SER1
strain was isolated and verified using 16s rDNA. The prodigiosin was purified using silica
chromatography and was analyzed by 1H-NMR spectroscopy. The cell cytotoxic effects of
Updating Fragility Curves for Portuguese Pre-Seismic Code Reinforced Concrete Buildings
This paper is part of a broader study under development at LNEC with the main aim of
defining general policies for the cost-effective seismic retrofitting of the existing
Portuguese building stock.
The paper will summarise the methodology implemented for determining accurate
capacity and fragility curves of existing pre-seismic design code reinforced concrete
(RC) buildings when subjected to seismic action. The methodology involved the
definition of probabilistic models of relevant input variables (geometry and materials),
performing advanced numerical models of RC buildings under seismic action, setting of
appropriate limit states and finally analysis of the results in order to derive the updated
curves for Portuguese building stock.
This paper will also present a comparison between curves obtained from the current
study and the corresponding curves currently being used in LNEC’s seismic risk
assessment platform (LNECloss).info:eu-repo/semantics/publishedVersio
Spatial Asymmetric Two dimensional Continuous Abelian Sandpile Model
We insert some asymmetries in the continuous Abelian sandpile models, such as
directedness and ellipticity. We analyze probability distribution of different
heights and also find the field theory corresponding to the models. Also we
find the fields associated with some height variables.Comment: 14 Pages, 11 Figure
Electroosmotic Pressure-Driven Flow through a Slit Micro-Channel with Electric and Magnetic Transverse Field
In the present study, flow through two-dimensional microchannel under an axial electric field, transverse electric and magnetic fields and with axial pressure gradient has been investigated numerically. Continuity and momentum equations were solved steadily with respect to the non-slip condition by using discrete finite volume method and a numerical code. The results show that in the presence of the axial electric field, applying transverse magnetic field reduces flow velocity. However, when the transverse electric field and axial electric field exist together, applying the transverse magnetic field increases the flow rate to a certain extent and then reduces the flow rate. Hartmann number like this amount of magnetic field is known as critical Hartmann number. Therefore, with the presence of transverse and axial electric fields and transverse magnetic field, the highest possible flow rate is for critical Hartmann number. It was also found that by increasing the pressure gradient within the microchannel, the critical Hartmann number decreases. Moreover, by increasing the transverse electric field, the sensitivity of critical Hartmann number to the pressure gradient decreases and its value tends to a specific number (about 1.5)
IMECE2009-10157 Contact Time Study of Microsystems Actuated by Ramp-Input Voltages
ABSTRACT This paper presents a model to analyze contact phenomenon in microsystems, actuated by ramp voltages, which has applications in frequency sweeping. First-order shear deformation theory is used to model dynamical system using finite element method, while finite difference method is applied to model squeeze film damping. The model is validated by static pull-in results. The presented hybrid FEM-FDM model is utilized to compute values of contact time and dynamic behavior. Considering this model, effects of different geometrical and mechanical parameters on contact time are studied. The influence of imposing the additional reverse voltage on dynamic characteristics of the system is also investigated. It is shown that magnitude and position of applying the reverse voltage is very important in preventing pull-in instability
Evaluation of the end colostomy complications and the risk factors influencing them in Iranian patients
Introduction: The aim of this study was to assess the prevalence of end colostomy complications and the evaluation of factors influencing outcome. Patients and methods: Three hundred and thirty patients with end colostomy were studied. All patient were recalled for examination for recent complications. Early complications included stoma site pain, early dermal irritation (during the first month after surgery), mucosal bleeding, stornal prolapse and psychosocial complications. Late complications included peristomal hernia, stomal stenosis, late dermal irritation (after the first month), stomal retraction, stomal necrosis and other stoma complications (perforation, fistula etc.). Probable underlying factors were studied. To evaluate risk factors affecting complications, univariable analysis and then multivariable analysis by binary logistic regression was performed. Results: One hundred and one (30.6) patients had no complications and the remainder had at least one of early or late complications. Overall, psychosocial complications, 56.4; mucosal bleeding, 34.5; early dermal irritation, 23.5 were the most frequent complications. Peristomal hernia (11.2) was the most common late complication. Those aged >40 years had significant associations with psychosocial problem (OR = 2.77), mucosal haemorrhage (OR = 2.19), and early dermal irritation (OR = 3.14). The risks of peristomal hernia and early dermal irritation are greater in the patients with BMI >25 kg/m2 (OR = 2.08 and 2.55, respectively). Conclusion: The risk of most prevalent complications of colostomy construction increases in elder patients. The high prevalence of psychosocial and skin problems in patients with a colostomy, needs special attention especially from the viewpoint of education by trained stoma nurses and preparation of standard equipment. © 2005 Blackwell Publishing Ltd
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