Signaling pathways in osteogenesis and osteoclastogenesis: Lessons from cranial sutures and applications to regenerative medicine.

One of the simplest models for examining the interplay between bone formation and resorption is the junction between the cranial bones. Although only roughly a quarter of patients diagnosed with craniosynostosis have been linked to known genetic disturbances, the molecular mechanisms elucidated from these studies have provided basic knowledge of bone homeostasis. This work has translated to methods and advances in bone tissue engineering. In this review, we examine the current knowledge of cranial suture biology derived from human craniosynostosis syndromes and discuss its application to regenerative medicine

A Massive Yang-Mills Theory based on the Nonlinearly Realized Gauge Group

We propose a subtraction scheme for a massive Yang-Mills theory realized via a nonlinear representation of the gauge group (here SU(2)). It is based on the subtraction of the poles in D-4 of the amplitudes, in dimensional regularization, after a suitable normalization has been performed. Perturbation theory is in the number of loops and the procedure is stable under iterative subtraction of the poles. The unphysical Goldstone bosons, the Faddeev-Popov ghosts and the unphysical mode of the gauge field are expected to cancel out in the unitarity equation. The spontaneous symmetry breaking parameter is not a physical variable. We use the tools already tested in the nonlinear sigma model: hierarchy in the number of Goldstone boson legs and weak power-counting property (finite number of independent divergent amplitudes at each order). It is intriguing that the model is naturally based on the symmetry SU(2)_L local times SU(2)_R global. By construction the physical amplitudes depend on the mass and on the self-coupling constant of the gauge particle and moreover on the scale parameter of the radiative corrections. The Feynman rules are in the Landau gauge.Comment: 44 pages, 1 figure, minor changes, final version accepted by Phys. Rev.

On the Use of Inertial Sensors in Educational Engagement Activities

Wearable sensors have been successfully used for a few decades in different sporting applications and its use has been constrained mostly to research projects. However, its positive impact has been recently adding other directions towards education, commercial and servicing. The establishment of Sports Engineering as a discipline is playing an important role in Australian universities where relevant material and emerging technologies are required to be taught and in certain circumstances developed. Some of these technologies include the adoption of inertial sensors (accelerometers and gyroscopes). This paper shares the impact of inertial sensors in building engagement in different educational activities at secondary level, with the purpose of engaging them into Sports Engineering disciplines, and at tertiary level through teaching undergraduate and post-graduate programs

Biomolecular Ultrasound Imaging of Phagolysosomal Function

Phagocytic clearance and lysosomal processing of pathogens and debris are essential functions of the innate immune system. However, the assessment of these functions in vivo is challenging because most nanoscale contrast agents compatible with noninvasive imaging techniques are made from nonbiodegradable synthetic materials that do not undergo regular lysosomal degradation. To overcome this challenge, we describe the use of an all-protein contrast agent to directly visualize and quantify phagocytic and lysosomal activities in vivo by ultrasound imaging. This contrast agent is based on gas vesicles (GVs), a class of air-filled protein nanostructures naturally expressed by buoyant microbes. Using a combination of ultrasound imaging, pharmacology, immunohistology, and live-cell optical microscopy, we show that after intravenous injection, GVs are cleared from circulation by liver-resident macrophages. Once internalized, the GVs undergo lysosomal degradation, resulting in the elimination of their ultrasound contrast. By noninvasively monitoring the temporal dynamics of GV-generated ultrasound signal in circulation and in the liver and fitting them with a pharmacokinetic model, we can quantify the rates of phagocytosis and lysosomal degradation in living animals. We demonstrate the utility of this method by showing how these rates are perturbed in two models of liver dysfunction: phagocyte deficiency and nonalcoholic fatty liver disease. The combination of proteolytically degradable nanoscale contrast agents and quantitative ultrasound imaging thus enables noninvasive functional imaging of cellular degradative processes

Field theoretical representation of the Hohenberg-Kohn free energy for fluids

To go beyond Gaussian approximation to the Hohenberg-Kohn free energy playing the key role in the density functional theory (DFT), the density functional \textit{integral} representation would be relevant, because field theoretical approach to perturbative calculations becomes available. Then the present letter first derives the associated Hamiltonian of density functional, explicitly including logarithmic entropy term, from the grand partition function expressed by configurational integrals. Moreover, two things are done so that the efficiency of the obtained form may be revealed: to demonstrate that this representation facilitates the field theoretical treatment of the perturbative calculation, and further to compare our perturbative formulation with that of the DFT.Comment: 5 pages, revtex, modified on 13 April 2000 [see eqs. (3), (6), and (13)

Theory of a Continuous Hc2_{c2} Normal-to-Superconducting Transition

I study the $H_{c2}$ transition within the Ginzburg-Landau model, with $m$-component order parameter $\psi_i$. I find a renormalized fixed point free energy, exact in $m\rightarrow\infty$ limit, suggestive of a $2$nd-order transition in contrast to a general belief of a $1$st-order transition. The thermal fluctuations for $H\neq 0$ force one to consider an infinite set of marginally relevant operators for $d<d_{uc}=6$. I find $d_{lc}=4$, predicting that the ODLRO does not survive thermal fluctuations in $d=2,3$. The result is a solution to a critical fixed point that was found to be inaccessible within $\epsilon=6-d$-expansion, previously considered in E.Brezin, D.R.Nelson, A.Thiaville, Phys.Rev.B {\bf 31}, 7124 (1985), and was interpreted as a $1$st-order transition.Comment: 4 pages, self-unpacking uuencoded compressed postscript file with a figure already inside text; to appear in Phys. Rev. Lett

Applicability of the Linear delta Expansion for the lambda phi^4 Field Theory at Finite Temperature in the Symmetric and Broken Phases

The thermodynamics of a scalar field with a quartic interaction is studied within the linear delta expansion (LDE) method. Using the imaginary-time formalism the free energy is evaluated up to second order in the LDE. The method generates nonperturbative results that are then used to obtain thermodynamic quantities like the pressure. The phase transition pattern of the model is fully studied, from the broken to the symmetry restored phase. The results are compared with those obtained with other nonperturbative methods and also with ordinary perturbation theory. The results coming from the two main optimization procedures used in conjunction with the LDE method, the Principle of Minimal Sensitivity (PMS) and the Fastest Apparent Convergence (FAC) are also compared with each other and studied in which cases they are applicable or not. The optimization procedures are applied directly to the free energy.Comment: 13 pages, 10 eps figures, revtex, replaced with published versio

A path integral approach to the dynamics of a random chain with rigid constraints

In this work the dynamics of a freely jointed random chain which fluctuates at constant temperature in some viscous medium is studied. The chain is regarded as a system of small particles which perform a brownian motion and are subjected to rigid constraints which forbid the breaking of the chain. For simplicity, all interactions among the particles have been switched off and the number of dimensions has been limited to two. The problem of describing the fluctuations of the chain in the limit in which it becomes a continuous system is solved using a path integral approach, in which the constraints are imposed with the insertion in the path integral of suitable Dirac delta functions. It is shown that the probability distribution of the possible conformations in which the fluctuating chain can be found during its evolution in time coincides with the partition function of a field theory which is a generalization of the nonlinear sigma model in two dimensions. Both the probability distribution and the generating functional of the correlation functions of the positions of the beads are computed explicitly in a semiclassical approximation for a ring-shaped chain.Comment: 36 pages, 2 figures, LaTeX + REVTeX4 + graphicx, minor changes in the text, reference adde