53 research outputs found
Non-minimal -type corrections to holographic superconductor
We study -dimensional holographic superconductors in the presence of
non-minimally coupled electromagnetic field to gravity by considering an
arbitrary linear combination of -type invariants with three parameters.
Our analytical analysis shows that the non-minimal couplings affect the
condensate and the critical temperature.Comment: Accepted for publication in Modern Physics Letters
Spinor coupling to the weak Poincare gauge theory of gravity in three dimensions
Minimal coupling of a Dirac field to gravity with the most general
non-propagating torsion is considered in (1+2)-dimensions. The field equations
are obtained from a lagrangian by a variational principle. The space-time
torsion is calculated algebraically in terms of a quadratic spinor condensate
plus coupling coefficients. Firstly we give circularly symmetric rotating exact
solutions that collapse to geometry in the absence of the Dirac
condensate. Secondly we investigate a BTZ-like solution.Comment: We added a new subsection, corrected syntax errors, extended
dicussion. To be published in Phys. Rev.
Anisotropic cosmological solutions to the gravity
We investigate anisotropic cosmological solutions of the theory with
non-minimal couplings between electromagnetic fields and gravity in
form. After we derive the field equations by the variational principle, we look
for spatially flat cosmological solutions with magnetic fields or electric
fields. Then we give exact anisotropic solutions by assuming the hyperbolic
expansion functions. We observe that the solutions approach to the isotropic
case in late-times.Comment: 16 pages, 5 figure
The non-minimally coupled symmetric teleparallel gravity with electromagnetic field
We construct a symmetric teleparallel gravity model which is non-minimally
coupled with electromagnetic field in four dimensions inspired by its
Riemannian equivalent. We derive the field equations by taking the variation of
this model, which is written here for the first time. Then, we find some
classes of spherically symmetric static solutions by the coincident gauge of
symmetric teleparallel spacetime.Comment: 16 page
Assessment of intra-oral repair systems for veneered zirconia and zirconia only
The aim of this study was to compare bond strength resin composites to porcelain laminate veneers in the indirect repair method to composite resins used in the direct repair method for cases of porcelain veneer fracture of zirconia-based fixed dental prostheses. In the study, the groups were formed with different percentages of areas to be repaired to mimic porcelain fractures in the mouth. The experimental group of veneered zirconia were as follows: Group A = 100% Zr surface; Group B = 70% Zr, 30% porcelain surface; Group C = 50% Zr, 50% porcelain surface; Group D = 30% Zr, 70% porcelain surface; Group E = 100% porcelain surface. The repairs of the specimens were made using composite resin systems in half of the groups and using porcelain laminate veneers in the other half. Specimens were embedded in acrylic blocks before surface treatments and repairs were applied. After surface conditioning, laminate veneers were applied to the first half of the groups, and composite repair systems were applied to the second half of the groups. After all specimens were aged by thermal cycling, their bond strength values were measured using a Universal Testing Machine, and the obtained data were recorded. The specimens were examined with a stereomicroscope and classified according to failure types (adhesive/cohesive/mixed). Bond strength values were evaluated based on independent-samples t-test statistics. According to the comparisons among the groups, the bond strength of the indirect repairs made with the laminate material was higher than the bond strength of the repairs made with the composite. There was a statistically significant difference in favor of the indirect repair groups among all groups except for Group C. The highest bond strength was found in Group A in the indirect repair method, while the lowest bond was found in the direct repair method in Group E. Adhesive failure was mostly seen in the groups that were repaired with the composite
Symmetric Teleparallel Gravity: Some exact solutions and spinor couplings
In this paper we elaborate on the symmetric teleparallel gravity (STPG)
written in a non-Riemannian spacetime with nonzero nonmetricity, but zero
torsion and zero curvature. Firstly we give a prescription for obtaining the
nonmetricity from the metric in a peculiar gauge. Then we state that under a
novel prescription of parallel transportation of a tangent vector in this
non-Riemannian geometry the autoparallel curves coincides with those of the
Riemannian spacetimes. Subsequently we represent the symmetric teleparallel
theory of gravity by the most general quadratic and parity conserving
lagrangian with lagrange multipliers for vanishing torsion and curvature. We
show that our lagrangian is equivalent to the Einstein-Hilbert lagrangian for
certain values of coupling coefficients. Thus we arrive at calculating the
field equations via independent variations. Then we obtain in turn conformal,
spherically symmetric static, cosmological and pp-wave solutions exactly.
Finally we discuss a minimal coupling of a spin-1/2 field to STPG.Comment: Accepted for publication in the International Journal of Modern
Physics
Dirac field in topologically massive gravity
We consider a Dirac field coupled minimally to the Mielke-Baekler model of
gravity and investigate cosmological solutions in three dimensions. We arrive
at a family of solutions which exists even in the limit of vanishing
cosmological constant.Comment: 12 pages. Title changed. Conclusion extended. Appendix added. To
appear in Gen. Rel. Gra
Metaproteogenomic analysis of saliva samples from Parkinson's disease patients with cognitive impairment
Cognitive impairment (CI) is very common in patients with Parkinson's Disease (PD) and progressively develops on a spectrum from mild cognitive impairment (PD-MCI) to full dementia (PDD). Identification of PD patients at risk of developing cognitive decline, therefore, is unmet need in the clinic to manage the disease. Previous studies reported that oral microbiota of PD patients was altered even at early stages and poor oral hygiene is associated with dementia. However, data from single modalities are often unable to explain complex chronic diseases in the brain and cannot reliably predict the risk of disease progression. Here, we performed integrative metaproteogenomic characterization of salivary microbiota and tested the hypothesis that biological molecules of saliva and saliva microbiota dynamically shift in association with the progression of cognitive decline and harbor discriminatory key signatures across the spectrum of CI in PD. We recruited a cohort of 115 participants in a multi-center study and employed multi-omics factor analysis (MOFA) to integrate amplicon sequencing and metaproteomic analysis to identify signature taxa and proteins in saliva. Our baseline analyses revealed contrasting interplay between the genus Neisseria and Lactobacillus and Ligilactobacillus genera across the spectrum of CI. The group specific signature profiles enabled us to identify bacterial genera and protein groups associated with CI stages in PD. Our study describes compositional dynamics of saliva across the spectrum of CI in PD and paves the way for developing non-invasive biomarker strategies to predict the risk of CI progression in PD.FEMS Research and Training Gran
Organik kaplamalı metalik malzemelerde kaplama etkinliği ve metal korozyonunun belirlenmesi
TEZ4057Tez (Yüksek Lisans) -- Çukurova Üniversitesi, Adana, 2000.Kaynakça (s.76-78) var.v, 78 s. ; 30 cm.
Effects of thiourea and its derivatives on the corrosion of mild steel in acidic media.
TEZ5461Tez (Doktora) -- Çukurova Üniversitesi, Adana, 2005.Kaynakça (s. 125-131) var.xvi, 132 s. ; 29 cm.The effects of thiourea(TU), methylthiourea(MTU), phenylthiourea(PTU), thioacedamide(TacA) and thiobenzamide(TBA) on the corrosion behavior of mild steel in 0.1M solution of H2SO4 have been investigated in relation to the concentration of thioamides and temperatures. AC impedance, polarization resistance measurement and polarization curves measurement techniques have been used to obtain experimental data...Tiyoüre(TU), metiltiyoüre(MTU), feniltiyoüre(PTU), tiyoasetamid(TAcA) ve tiyobenzamid(TBA) in yumuşak çeliğin 0,1M H2SO4 çözeltisi içindeki korozyon davranışı üzerine etkileri derişime ve sıcaklığa bağlı olarak araştırılmıştır. Deneysel verileri elde etmek için alternatif akım impedansı, polarizasyon direnci ölçme ve akım-potansiyel eğrilerinin elde edilmesi yöntemleri kullanılmıştır..
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