233 research outputs found
Utilidade dos testes de sensibilidade do bacilo da tuberculose em saúde pública
Fez-se revisão na indicação dos testes de sensibilidade do bacilo tuberculoso, levando em conta sua utilidade em Saúde Pública ou em casos individualizados. Discutiram-se as dificuldades técnicas para a execução de um exame confiável, bem como os problemas existentes para a sua interpretação.The indications of sensitivity tests for tuberculous bacilli are reviewed, and their usefulness both in public health and individual cases is considered. Technical difficulties and some misinterpretations are discussed within the scop of our present knowledge
Phase transition of triangulated spherical surfaces with elastic skeletons
A first-order transition is numerically found in a spherical surface model
with skeletons, which are linked to each other at junctions. The shape of the
triangulated surfaces is maintained by skeletons, which have a one-dimensional
bending elasticity characterized by the bending rigidity , and the surfaces
have no two-dimensional bending elasticity except at the junctions. The
surfaces swell and become spherical at large and collapse and crumple at
small . These two phases are separated from each other by the first-order
transition. Although both of the surfaces and the skeleton are allowed to
self-intersect and, hence, phantom, our results indicate a possible phase
transition in biological or artificial membranes whose shape is maintained by
cytoskeletons.Comment: 15 pages with 10 figure
Isabelle/PIDE as Platform for Educational Tools
The Isabelle/PIDE platform addresses the question whether proof assistants of
the LCF family are suitable as technological basis for educational tools. The
traditionally strong logical foundations of systems like HOL, Coq, or Isabelle
have so far been counter-balanced by somewhat inaccessible interaction via the
TTY (or minor variations like the well-known Proof General / Emacs interface).
Thus the fundamental question of math education tools with fully-formal
background theories has often been answered negatively due to accidental
weaknesses of existing proof engines.
The idea of "PIDE" (which means "Prover IDE") is to integrate existing
provers like Isabelle into a larger environment, that facilitates access by
end-users and other tools. We use Scala to expose the proof engine in ML to the
JVM world, where many user-interfaces, editor frameworks, and educational tools
already exist. This shall ultimately lead to combined mathematical assistants,
where the logical engine is in the background, without obstructing the view on
applications of formal methods, formalized mathematics, and math education in
particular.Comment: In Proceedings THedu'11, arXiv:1202.453
Phase transition of meshwork models for spherical membranes
We have studied two types of meshwork models by using the canonical Monte
Carlo simulation technique. The first meshwork model has elastic junctions,
which are composed of vertices, bonds, and triangles, while the second model
has rigid junctions, which are hexagonal (or pentagonal) rigid plates.
Two-dimensional elasticity is assumed only at the elastic junctions in the
first model, and no two-dimensional bending elasticity is assumed in the second
model. Both of the meshworks are of spherical topology. We find that both
models undergo a first-order collapsing transition between the smooth spherical
phase and the collapsed phase. The Hausdorff dimension of the smooth phase is
H\simeq 2 in both models as expected. It is also found that H\simeq 2 in the
collapsed phase of the second model, and that H is relatively larger than 2 in
the collapsed phase of the first model, but it remains in the physical bound,
i.e., H<3. Moreover, the first model undergoes a discontinuous surface
fluctuation transition at the same transition point as that of the collapsing
transition, while the second model undergoes a continuous transition of surface
fluctuation. This indicates that the phase structure of the meshwork model is
weakly dependent on the elasticity at the junctions.Comment: 21 pages, 12 figure
On a class of stationary loops on SO(n) and the existence of multiple twisting solutions to a nonlinear elliptic system subject to a hard incompressibility constraint
For full abstract please refer to http://dx.doi.org/10.1186/s13661-018-1047-
Antibacterial activity of Thymoquinone, an active principle of Nigella sativa and its potency to prevent bacterial biofilm formation
<p>Abstract</p> <p>Background</p> <p>Thymoquinone is an active principle of <it>Nigella sativa </it>seed known as "Habbah Al-Sauda" in Arabic countries and "Sinouj" in Tunisia. Bacterial biofilms tend to exhibit significant tolerance to antimicrobials drugs during infections.</p> <p>Methods</p> <p>The antibacterial activity of Thymoquinone (TQ) and its biofilm inhibition potencies were investigated on 11 human pathogenic bacteria. The growth and development of the biofilm were assessed using the crystal violet (CV) and the 2, 3-bis [2-methyloxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide (XTT) reduction assay.</p> <p>Results</p> <p>TQ exhibited a significant bactericidal activity against the majority of the tested bacteria (MICs values ranged from 8 to 32 μg/ml) especially Gram positive cocci (<it>Staphylococcus aureus </it>ATCC 25923 and <it>Staphylococcus epidermidis </it>CIP 106510). Crystal violet assay demonstrated that the minimum biofilm inhibition concentration (BIC50) was reached with 22 and 60 μg/ml for <it>Staphylococcus aureus </it>ATCC 25923 and <it>Staphylococcus epidermidis </it>CIP 106510 respectively. In addition our data revealed that cells oxidative activity was influenced by TQ supplementation. In the same way, TQ prevented cell adhesion to glass slides surface.</p> <p>Conclusion</p> <p>The ability of TQ to prevent biofilm formation warrants further investigation to explore its use as bioactive substances with antibiofilm potential.</p
Fractionation of a Herbal Antidiarrheal Medicine Reveals Eugenol as an Inhibitor of Ca2+-Activated Cl− Channel TMEM16A
The Ca2+-activated Cl− channel TMEM16A is involved in epithelial fluid secretion, smooth muscle contraction and neurosensory signaling. We identified a Thai herbal antidiarrheal formulation that inhibited TMEM16A Cl− conductance. C18-reversed-phase HPLC fractionation of the herbal formulation revealed >98% of TMEM16A inhibition activity in one out of approximately 20 distinct peaks. The purified, active compound was identified as eugenol (4-allyl-2-methoxyphenol), the major component of clove oil. Eugenol fully inhibited TMEM16A Cl− conductance with single-site IC50∼150 µM. Eugenol inhibition of TMEM16A in interstitial cells of Cajal produced strong inhibition of intestinal contraction in mouse ileal segments. TMEM16A Cl− channel inhibition adds to the list of eugenol molecular targets and may account for some of its biological activities
Transcranial modulation of brain oscillatory responses: A concurrent tDCS–MEG investigation
The physiological mechanisms underlying the effects of transcranial direct current stimulation (tDCS) are still largely unknown. To provide novel insight into the neurobiology of tDCS, stimulation was applied concurrently with Magnetoencephalography (MEG). This occurred while participants completed a visuomotor task before, during and after stimulation. Motor beta band (15–30 Hz) and visual gamma band (30–80 Hz) responses were localised using Synthetic Aperture Magnetometry (SAM). The resulting evoked and induced brain oscillatory responses were analysed. A significant reduction of average power was observed in the visual gamma band for anodal compared to sham stimulation. The magnitude of motor evoked responses was also demonstrated to be modulated by anodal tDCS. These results highlight that MEG can be used to draw inferences on the cortical mechanisms of DC stimulation
Stimulating somatosensory psychophysics: a double-blind, sham-controlled study of the neurobiological mechanisms of tDCS
In this study, the influence of tDCS on vibrotactile adaptation is investigated. Double-blind tDCS (Anodal/Sham) of 1 mA was delivered for 600 s to electrodes positioned in a somatosensory/contralateral orbit montage. Stimulation was applied between blocks of the implemented amplitude discrimination tasks. Amplitude discrimination thresholds were significantly degraded during adaptation trials, compared to those achieved at baseline but tDCS failed to modify task performance. Using Bayesian statistics, this finding was revealed to constitute substantial evidence for the null hypothesis. The failure of DC stimulation to alter performance is discussed in the context of several factors that may have confounded the induction of changes in cortical plasticity
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