1,619 research outputs found
Osteoblast interactions within a biomimetic apatite microenvironment.
Numerous reports have shown that accelerated apatites can mediate osteoblastic differentiation in vitro and bone formation in vivo. However, how cells interact within the apatite microenvironment remains largely unclear, despite the vast literature available today. In response, this study evaluates the in vitro interactions of a well-characterized osteoblast cell line (MC3T3-E1) with the apatite microenvironment. Specifically, cell attachment, spreading, and viability were evaluated in the presence and absence of serum proteins. Proteins were found to be critical in the mediation of cell-apatite interactions, as adherence of MC3T3-E1 cells to apatite surfaces without protein coatings resulted in significant levels of cell death within 24 h in serum-free media. In the absence of protein-apatite interaction, cell viability could be "rescued" upon treatment of MC3T3-E1 cells with inhibitors to phosphate (PO(4) (3-)) transport, suggesting that PO(4) (3-) uptake may play a role in viability. In contrast, rescue was not observed upon treatment with calcium (Ca(2+)) channel inhibitors. Interestingly, a rapid "pull-down" of extracellular Ca(2+) and PO(4) (3-) ions onto the apatite surface could be measured upon the incubation of apatites with α-MEM, suggesting that cells may be subject to changing levels of Ca(2+) and PO(4) (3-) within their microenvironment. Therefore, the biomimetic apatite surface may significantly alter the microenvironment of adherent osteoblasts and, as such, be capable of affecting both cell survival and differentiation
Flow Equations for U_k and Z_k
By considering the gradient expansion for the wilsonian effective action S_k
of a single component scalar field theory truncated to the first two terms, the
potential U_k and the kinetic term Z_k, I show that the recent claim that
different expansion of the fluctuation determinant give rise to different
renormalization group equations for Z_k is incorrect. The correct procedure to
derive this equation is presented and the set of coupled differential equations
for U_k and Z_k is definitely established.Comment: 5 page
Constructive Matrix Theory
We extend the technique of constructive expansions to compute the connected
functions of matrix models in a uniform way as the size of the matrix
increases. This provides the main missing ingredient for a non-perturbative
construction of the field theory on the Moyal four
dimensional space.Comment: 12 pages, 3 figure
On the Connection Between Momentum Cutoff and Operator Cutoff Regularizations
Operator cutoff regularization based on the original Schwinger's proper-time
formalism is examined. By constructing a regulating smearing function for the
proper-time integration, we show how this regularization scheme simulates the
usual momentum cutoff prescription yet preserves gauge symmetry even in the
presence of the cutoff scales. Similarity between the operator cutoff
regularization and the method of higher (covariant) derivatives is also
observed. The invariant nature of the operator cutoff regularization makes it a
promising tool for exploring the renormalization group flow of gauge theories
in the spirit of Wilson-Kadanoff blocking transformation.Comment: 28 pages in plain TeX, no figures. revised and expande
Dimensional structural constants from chiral and conformal bosonization of QCD
We derive the dimensional non-perturbative part of the QCD effective action
for scalar and pseudoscalar meson fields by means of chiral and conformal
bosonization. The related structural coupling constants L_5 and L_8 of the
chiral lagrangian are estimated using general relations which are valid in a
variety of chiral bosonization models without explicit reference to model
parameters. The asymptotics for large scalar fields in QCD is elaborated, and
model-independent constraints on dimensional coupling constants of the
effective meson lagrangian are evaluated. We determine also the interaction
between scalar quarkonium and the gluon density and obtain the scalar
glueball-quarkonium potential.Comment: 21 pages, LaTe
Wegner-Houghton equation and derivative expansion
We study the derivative expansion for the effective action in the framework
of the Exact Renormalization Group for a single component scalar theory. By
truncating the expansion to the first two terms, the potential and the
kinetic coefficient , our analysis suggests that a set of coupled
differential equations for these two functions can be established under certain
smoothness conditions for the background field and that sharp and smooth
cut-off give the same result. In addition we find that, differently from the
case of the potential, a further expansion is needed to obtain the differential
equation for , according to the relative weight between the kinetic and
the potential terms. As a result, two different approximations to the
equation are obtained. Finally a numerical analysis of the coupled equations
for and is performed at the non-gaussian fixed point in
dimensions to determine the anomalous dimension of the field.Comment: 15 pages, 3 figure
Renormalization Group Flow Equations and the Phase Transition in O(N)-models
We derive and solve flow equations for a general O(N)-symmetric effective
potential including wavefunction renormalization corrections combined with a
heat-kernel regularization. We investigate the model at finite temperature and
study the nature of the phase transition in detail. Beta functions, fixed
points and critical exponents \beta, \nu, \delta and \eta for various N are
independently calculated which allow for a verification of universal scaling
relations.Comment: 34 pages, 3 tables, 11 postscript figures, LaTe
Nanocrystal- and Dislocation-Related Luminescence in Si Matrix with InAs Nanocrystals
We have studied the inïŹuence of ion implantation and post-implantation annealing regimes on the structural and optical properties of silicon matrix with ion-beam synthesized InAs nanocrystals. (100) Si wafers were implanted at 25 and 500 ±C, subsequently with high ïŹuences of As and In ions. After implantation the samples were processed by furnace and rapid thermal annealing at 900, 950 and 1050 ±C. A part of the samples implanted at 25 ±C was additionally exposed to H+2 ions (100 keV, 1.2 Ă 1016 cmâ2 in terms of atomic hydrogen). This
procedure was performed to obtain an internal getter. In order to characterize the implanted samples transmission electron microscopy and low-temperature photoluminescence techniques were employed. It was demonstrated that by introducing getter, varying the ion implantation temperature, ion ïŹuences and post-implantation annealing duration, and temperature it is possible to form InAs nanocrystals in the range of sizes of 2â80 nm and create various concentration and distribution of diËerent types of secondary defects. The last ones cause in turn the appearance in photoluminescence spectra dislocation-related D1, D2 and D4 lines at 0.807, 0.870 and 0.997 eV, respectively
Lorentz and CPT symmetries in commutative and noncommutative spacetime
We investigate the fermionic sector of a given theory, in which massive and
charged Dirac fermions interact with an Abelian gauge field, including a non
standard contribution that violates both Lorentz and CPT symmetries. We offer
an explicit calculation in which the radiative corrections due to the fermions
seem to generate a Chern-Simons-like effective action. Our results are obtained
under the general guidance of dimensional regularization, and they show that
there is no room for Lorentz and CPT violation in both commutative and
noncommutative spacetime.Comment: RevTex4, 7 pages, to be published in J. Phys.
Carbon Fiber Insoles Enhance Perception of Performance Despite Variable Objective Outcomes: Specific to the Moderately Active Individual
International Journal of Exercise Science 16(4): 885-897, 2023. Carbon fiber insoles (CFIs) may benefit performance in elite athletes, however, their use in moderately active individuals has been adopted without evidence supporting such enhancements in this population. Fifteen male subjects performed vertical jump (VJ) and repeat treadmill sprint tests before and after a VO2peak while wearing 1) CFIs and 2) control insoles (CON). Subjects completed a subjective survey regarding their perceived performance abilities for both conditions. There were no significant differences between CFIs and CON in VJ height, sprint distance, heart rate following sprints; and rate of oxygen consumption, perceived fatigue, and perceived exertion at 85% of maximal speed (p \u3e 0.05) during the VO2peak. At maximal speed, although there was no difference between conditions in peak rate of oxygen consumption (95%CI [-4.85, 0.21]) and respiratory exchange ratio (95%CI [-0.01, 0.03]), CFIs resulted in a reduced level of perceived fatigue (95%CI [-1, 0]) and perceived exertion (95%CI [-2, 0]) compared to CON. Subjects subjectively reported increased feelings of âpropulsion or explosivenessâ (p = 0.026) and being able to âperform better while jumpingâ (p = 0.029) while wearing CFIs. Heightened perceptions of performance enhancements when wearing CFIs indicate, in the moderately active, perceptual benefits could be more influential for determining CFI use
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