55 research outputs found
Weak solvability of the unconditionally stable difference scheme for the coupled sine-Gordon system
In this paper, we study the existence and uniqueness of weak solution for the system of finite difference schemes for coupled sine-Gordon equations. A novel first order of accuracy unconditionally stable difference scheme is considered. The variational method also known as the energy method is applied to prove unique weak solvability.We also present a new unified numerical method for the approximate solution of this problem by combining the difference scheme and the fixed point iteration. A test problem is considered, and results of numerical experiments are presented with error analysis to verify the accuracy of the proposed numerical method
Effects of Dissolving Solutions on the Accuracy of an Electronic Apex Locator-Integrated Endodontic Handpiece
The effects of three dissolving agents on the accuracy of an electronic apex locator- (EAL-) integrated endodontic handpiece during retreatment procedures were evaluated. The true lengths (TLs) of 56 extracted incisor teeth were determined visually. Twenty teeth were filled with gutta-percha and a resin-based sealer (group A), 20 with gutta-percha and a zinc oxide/eugenol-based sealer (group B), and 16 roots were used as the control group (group C). All roots were prepared to TL. Guttasolv, Resosolv, and Endosolv E were used as the dissolving solutions. Two evaluations of the handpiece were performed: the apical accuracy during the auto reverse function (ARL) and the apex locator function (EL) alone. The ARL function of the handpiece gave acceptable results. There were significant differences between the EL mode measurements and the TL (P<0.05). In these comparisons, Tri Auto ZX EL mode measurements were significantly shorter than those of the TL
On Third Order Stable Difference Scheme for Hyperbolic Multipoint Nonlocal Boundary Value Problem
This paper presents a third order of accuracy stable difference scheme for the approximate solution of multipoint nonlocal boundary value problem of the hyperbolic type in a Hilbert space with self-adjoint positive definite operator. Stability estimates for solution of the difference scheme are obtained. Some results of numerical experiments that support theoretical statements are presented
Preparation of Ion Imprinted SPR Sensor for Real-Time Detection of Silver(I) Ion from Aqueous Solution
The aim of the submitted study is to develop molecular imprinting based surface plasmon resonance
(SPR) sensor for real-time silver ion detection. For this purpose polymeric nanofilm layer on the gold SPR
chip surface was prepared via UV polymerization of acrylic acid at 395 nm for 30 minutes. N-methacryloyl-
L cysteine used as the functional monomer to recognize the silver(I) ions from the aqueous solutions and
methylene bisacrylamide used as the crosslinker for obtaining structural rigidity of the formed cavities.
Silver(I) solutions with different concentrations were applied to SPR system to investigate the efficiency of
the imprinted SPR sensor in real time. For the control experiments, non-imprinted SPR sensor was also
prepared as described above without addition of template “silver(I) ions”. Prepared SPR sensors were
characterized with atomic force microscopy (AFM). In order to show the selectivity of the silver(I) imprinted
SPR sensor, competitive adsorption of Cu(II), Pb(II), Ni(II) ions was investigated.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3489
Weak field and slow motion limits in energy-momentum powered gravity
We explore the weak field and slow motion limits, Newtonian and
Post-Newtonian limits, of the energy-momentum powered gravity (EMPG), viz., the
energy-momentum squared gravity (EMSG) of the form
with
and being constants. We have shown that EMPG with and
general relativity (GR) are not distinguishable by local tests, say, the Solar
System tests; as they lead to the same gravitational potential form, PPN
parameters, and geodesics for the test particles. However, within the EMPG
framework, , the mass of an astrophysical object inferred from
astronomical observations such as planetary orbits and deflection of light,
corresponds to the effective mass , being the actual physical mass and
being the modification due to EMPG. Accordingly, while in GR we simply have the
relation , in EMPG we have . Within
the framework of EMPG, if there is information about the values of
pair or from other independent phenomena (from
cosmological observations, structure of the astrophysical object, etc.), then
in principle it is possible to infer not only alone from
astronomical observations, but and separately. For a proper
analysis within EMPG framework, it is necessary to describe the slow motion
condition (also related to the Newtonian limit approximation) by (where and ), whereas this condition leads to in
GR.Comment: 12 pages, no figures and table
Screening in a new modified gravity model
We study a new model of Energy-Momentum Squared Gravity (EMSG), called
Energy-Momentum Log Gravity (EMLG), constructed by the addition of the term
, envisaged
as a correction, to the Einstein-Hilbert action with cosmological constant
. The choice of this modification is made as a specific way of
including new terms in the right-hand side of the Einstein field equations,
resulting in constant effective inertial mass density and, importantly, leading
to an explicit exact solution of the matter energy density in terms of
redshift. We look for viable cosmologies, in particular, an extension of the
standard CDM model. EMLG provides an effective dynamical dark energy
passing below zero at large redshifts, accommodating a mechanism for screening
in this region, in line with suggestions for alleviating some of the
tensions that arise between observational data sets within the standard
CDM model. We present a detailed theoretical investigation of the
model and then constrain the free parameter , a normalisation of
, using the latest observational data. The data does not rule out the
CDM limit of our model (), but prefers slightly negative
values of the EMLG model parameter (), which leads to
the screening of . We also discuss how EMLG relaxes the persistent
tension that appears in the measurements of within the standard
CDM model.Comment: 17 pages, 11 figures, 1 table; matches the version published in EPJ
Evaluation of the effect of mitral stenosis severity on the left ventricular systolic function using isovolumic myocardial acceleration
Background: Isovolumic acceleration (IVA) is a new tissue Doppler parameter in the assessment of systolic function of both left and right ventricles. It remains unaffected with the changes in pre- and after-load within the physiological range. The aim of our study was to assess the effect of mitral stenosis degree, which is determined by echocardiography, on the left ventricular (LV) function using IVA. Methods: A total number of 62 patients with mitral stenosis (MS) and 32 healthy controls were examined. The severity of MS (mild, moderate, and severe) was determined on the basis of mitral valve area (MVA) and the mean diastolic mitral gradient findings. The peak myocardial velocities during isovolumic contraction, systole, early diastole and late diastole were measured by using tissue Doppler imaging (TDI). Results: All TDI-derived global LV basal wall systolic (peak myocardial isovolumic contraction velocity, peak myocardial systolic velocity and IVA), and diastolic velocities (peak early and late diastolic velocities) were significantly decreased in the patients with MS, compared to the healthy patients (p < 0.001, for all). However, IVA was not different when the degree of MS was evaluated (p = 0.114). In addition, IVA was not correlated with the MVA (r = 0.185, p = 0.150). Conclusions: Left ventricular function is impaired in patients with MS regardless of the severity of the disease.
A repertoire of biomedical applications of noble metal nanoparticles
Noble metals comprise any of several metallic chemical elements that are outstandingly resistant to corrosion and oxidation, even at elevated temperatures. This group is not strictly defined, but the tentative list includes ruthenium, rhodium, palladium, silver, osmium, iridium, platinum and gold, in order of atomic number. The emerging properties of noble metal nanoparticles are attracting huge interest from the translational scientific community and have led to an unprecedented expansion of research and exploration of applications in biotechnology and biomedicine. Noble metal nanomaterials can be synthesised both by top-down and bottom up approaches, as well as via organism-assisted routes, and subsequently modified appropriately for the field of use. Nanoscale analogues of gold, silver, platinum, and palladium in particular, have gained primary importance owing to their excellent intrinsic properties and diversity of applications; they offer unique functional attributes, which are quite unlike the bulk material. Modulation of noble metal nanoparticles in terms of size, shape and surface functionalisation has endowed them with unusual capabilities and manipulation at the chemical level, which can lead to changes in their electrical, chemical, optical, spectral and other intrinsic properties. Such flexibility in multi-functionalisation delivers ‘Ockham's razor’ to applied biomedical science. In this feature article, we highlight recent advances in the adaptation of noble metal nanomaterials and their biomedical applications in therapeutics, diagnostics and sensing
The effect of residual calcium hydroxide on the accuracy of a contemporary electronic apex locator
Objective. The aim of this study was to evaluate the effect of residual calcium hydroxide [Ca(OH)(2)] on the accuracy of an electronic apex locator (EAL). Materials and methods. Working lengths (WLs) of 56 extracted maxillary incisors were determined initially by two different methods. The first method used the ` APEX' reading of the EAL as a reference point, 0.5 mm was subtracted and recorded as WL0. The second method used the '0.5' reading and the score was recorded as WL0.5 without subtraction. The roots were prepared to WL0 and divided randomly into three experimental groups (n = 16) (1 mm in group A, 2 mm in group B and 4 mm in group C) and a control (n = 8). Specimens in all experimental groups were filled with Ca(OH)(2) paste. Following its removal, WLs were re-determined with the same methods. Results. In group C, pre/ post WLs were significantly different (p < 0.05). No significant difference was observed between the other experimental groups and the control group. Conclusion. Accuracy of EAL decreased proportionally with the amount of paste remaining at the +/- 0.5-mm tolerance level. Ca(OH)(2) paste remnants may cause incorrect EAL readings
- …