Hopf Bifurcations in a Watt Governor With a Spring

This paper pursues the study carried out by the authors in "Stability and Hopf bifurcation in a hexagonal governor system", focusing on the codimension one Hopf bifurcations in the hexagonal Watt governor differential system. Here are studied the codimension two, three and four Hopf bifurcations and the pertinent Lyapunov stability coefficients and bifurcation diagrams, ilustrating the number, types and positions of bifurcating small amplitude periodic orbits, are determined. As a consequence it is found an open region in the parameter space where two attracting periodic orbits coexist with an attracting equilibrium point.Comment: 30 pages and 7 figure

Lifestyle, Inflammation, and Vascular Calcification in Kidney Transplant Recipients:Perspectives on Long-Term Outcomes

After decades of pioneering, kidney transplantation is now established as preferred treatment for patients with end-stage renal disease. Yet, there is still need for optimizing long-term health state and downturn the burden of graft failure of kidney transplant recipients (KTR). In this thesis we describe our studies on potentially modifiable risk factors for graft failure and premature death, in the field of lifestyle, diet and exposure to toxic contaminants, which are underexplored areas in kidney transplantation. This approach unfolded potentially cost-effective risk management opportunities for outpatient KTR. Dietary interventional strategies based on individualized recommendations to increase fruit, vegetable, and fish intake in KTR may substantially alleviate the burden of premature death among outpatient KTR. Further investigation of the potential impact of policy measures and clinical guidance to decrease the exposure to cadmium and other toxic environmental contaminants is also warranted to decrease the burden of graft failure and function decline. The second part of this thesis supports the notion that non-traditional risk factors, such as chronic low-grade inflammation, persistent redox imbalance, and deregulated mineral and bone metabolism, may at least partly explain the excess risk of vascular disease in outpatient KTR. Further research on these non-traditional risk factors is also warranted as it may pave the way towards decreasing the long-standing burden of graft failure and premature death post-kidney transplantation

Escaping Antiangiogenic Therapy: Strategies Employed by Cancer Cells

Indexación: Web of ScienceTumor angiogenesis is widely recognized as one of the hallmarks of cancer. Consequently, during the last decades the development and testing of commercial angiogenic inhibitors has been a central focus for both basic and clinical cancer research. While antiangiogenic drugs are now incorporated into standard clinical practice, as with all cancer therapies, tumors can eventually become resistant by employing a variety of strategies to receive nutrients and oxygen in the event of therapeutic assault. Herein, we concentrate and review in detail three of the principal mechanisms of antiangiogenic therapy escape: (1) upregulation of compensatory/alternative pathways for angiogenesis; (2) vasculogenic mimicry; and (3) vessel co-option. We suggest that an understanding of how a cancer cell adapts to antiangiogenic therapy may also parallel the mechanisms employed in the bourgeoning tumor and isolated metastatic cells delivering responsible for residual disease. Finally, we speculate on strategies to adapt antiangiogenic therapy for future clinical uses.http://www.mdpi.com/1422-0067/17/9/148

Compensation for effects of ambient temperature on rare-earth doped fiber optic thermometer

Variations in ambient temperature have a negative effect on the performance of any fiber optic sensing system. A change in ambient temperature may alter the design parameters of fiber optic cables, connectors, sources, detectors, and other fiber optic components and eventually the performance of the entire system. The thermal stability of components is especially important in a system which employs intensity modulated sensors. Several referencing schemes have been developed to account for the variable losses that occur within the system. However, none of these conventional compensating techniques can be used to stabilize the thermal drift of the light source in a system based on the spectral properties of the sensor material. The compensation for changes in ambient temperature becomes especially important in fiber optic thermometers doped with rare earths. Different approaches to solving this problem are searched and analyzed

“Galectin-1 Induces Central and Peripheral Cell Death: Implications in T-Cell Physiopathology”

The immune system has a remarkable capacity to maintain a state of equilibrium even as it responds to a diverse array of foreign proteins and despite its contact exposure to self-antigens. Apoptosis is one of the mechanisms aimed at preserving the homeostasis after the completion of an immune response, thus returning the immune system to a basal state and warranting the elimination of autoagressive cells in both central and peripheral lymphoid organs. Targeted deletions in critical genes involved in the apoptotic death machinery together with natural spontaneous mutations have clearly shown the importance of apoptosis in the regulation of the immune response. This complex scenario of stimulatory and inhibitory genes has been enriched with the finding that galectin-1, a 14.5 kDa β-galactoside-binding protein, is able to induce apoptosis of immature cortical thymocytes and mature T cells by cross-linking cell surface glycoconjugates. Galectin-1 is present not only in central and peripheral lymphoid organs, but also at sites of immune privilege. In the present article we will discuss the implications of galectin-1-induced apoptosis in T-cell physiopathology in an attempt to validate its therapeutic potential in autoimmune and inflammatory diseases

Supercritical colliding wind binaries

Context. Particle-accelerating colliding-wind binaries (PACWBs) are systems that are formed by two massive and hot stars and produce nonthermal (NT) radiation. The key elements of these systems are fast winds and the shocks that they create when they collide. Binaries with nonaccreting young pulsars have also been detected as NT emitters, again as a consequence of the wind-wind interaction. Black holes (BHs) might produce NT radiation by this mechanism if they accrete at super-Eddington rates. In such cases, the disk is expected to launch a radiation-driven wind, and if this wind has an equatorial component, it can collide with the companion star yielding a PACWB. These systems are supercritical colliding wind binaries (SCWBs). Aims. We aim to characterize the particle acceleration and NT radiation produced by the collision of winds in binary systems composed of a superaccreting BH and an early-type star. Methods. We estimated the terminal velocity of the disk-driven wind by calculating the spatial distribution of the radiation fields and their effect on disk particles. We then found the location of the wind collision region and calculated the timescales of energy gain and losses of relativistic particles undergoing diffusive acceleration. With this information, we were able to compute the associated spectral energy distribution of the radiation. Results. We find that the interaction of winds can produce NT emission from radio up to tens of GeV, with luminosities in the range of $\sim 10^{33}-10^{35} \, {\rm erg \, s^{-1}}$, which for the most part are contributed by electron synchrotron and inverse Compton radiation. Conclusions. We conclude that SCWBs, such as some ultraluminous X-ray sources and some Galactic X-ray binaries, are capable of accelerating cosmic rays and producing NT electromagnetic emission from radio to $\gamma$-rays, in addition to the thermal components.Comment: 13 pages, 10 figures. Accepted for publication in Astronomy and Astrophysic

Integrability and explicit solutions in some Bianchi cosmological dynamical systems

The Einstein field equations for several cosmological models reduce to polynomial systems of ordinary differential equations. In this paper we shall concentrate our attention to the spatially homogeneous diagonal G_2 cosmologies. By using Darboux's theory in order to study ordinary differential equations in the complex projective plane CP^2 we solve the Bianchi V models totally. Moreover, we carry out a study of Bianchi VI models and first integrals are given in particular cases

Group Strategyproof Pareto-Stable Marriage with Indifferences via the Generalized Assignment Game

We study the variant of the stable marriage problem in which the preferences of the agents are allowed to include indifferences. We present a mechanism for producing Pareto-stable matchings in stable marriage markets with indifferences that is group strategyproof for one side of the market. Our key technique involves modeling the stable marriage market as a generalized assignment game. We also show that our mechanism can be implemented efficiently. These results can be extended to the college admissions problem with indifferences

Stable schedule matching under revealed preference

Baiou and Balinski (Math. Oper. Res., 27 (2002) 485) studied schedule matching where one determines the partnerships that form and how much time they spend together, under the assumption that each agent has a ranking on all potential partners. Here we study schedule matching under more general preferences that extend the substitutable preferences in Roth (Econometrica 52 (1984) 47) by an extension of the revealed preference approach in Alkan (Econom. Theory 19 (2002) 737). We give a generalization of the GaleShapley algorithm and show that some familiar properties of ordinary stable matchings continue to hold. Our main result is that, when preferences satisfy an additional property called size monotonicity, stable matchings are a lattice under the joint preferences of all agents on each side and have other interesting structural properties